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Indian River Lagoon Management Areas:

 

Tomoka Map

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Area Desciption

The Tomoka Management Area consists of a single impoundment (A-2, Volusia County) of approximately 445.5 ha. It is bounded to the north by tributaries of Bulow Creek, on the east by the Halifax River, on the south by unimpounded marshes and the Tomoka Basin, and on the west by woodlands which are drained by ditches that flow into Tomoka Basin.

The west side of the area borders on Bulow State Park, whereas the areas below mean high water form part of the Tomoka Marsh Aquatic Preserve. There is no development around this area, but there is considerable recreational use, particularly on the south side (fishing, crabbing, camping).

In the past, the marsh was extensively ditched for mosquito control, and the ditches are still evident today. There is a large breach (12-15 m) on the north end of the dike, and a spoil deposition area along the east border. The Florida Inland Navigation District (FIND) has proposed to expand this spoil area and to improve the road leading to it (including installation of culverts below the road). There are also plans to purchase and preserve the whole area as mitigation for the spoil deposition, a project that FIND and Aquatic Preserve personnel consider of high priority.

The marsh vegetation is composed primarily of Distichlis spicata and Salicornia spp. , with Avicennia germinans, Spartina bakeri and Juncus roemerianus occurring irregularly throughout the marsh. Along the ditches, vegetation consists of Salicornia and Borrichia, with numerous Opuntia, Distichlis, and a few cedar trees. Freshwater species such as Typha and Scirpus are found along the western boundaries, whereas palms, pines, and hardwoods with dense palmetto undergrowth occur on hammocks and high islands within the marsh.

From 1968 to 1972, the area was seasonally flooded for mosquito control and high water levels were maintained during winter to provide waterfowl habitat. From 1972 to 1980, the winter management was discontinued, and in 1980 all management ceased.

Management Plans
Plans for this area are being developed by Tomoka Aquatic Preserve personnel. They will be included here as soon as they are available.


Mosquito Lagoon Map

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Area Description

The Mosquito Lagoon Management Area (MLMA) extends from approximately 20 miles north of Ponce Inlet (Volusia County) south for approximately 55 miles thereby including impoundments along both the eastern and western edge of Mosquito Lagoon. The MLMA thus encompasses the Mosquito Lagoon Aquatic Preserve (MLAP), the Canaveral National Seashore's (CNS) marshes (which are located in Volusia County). The southern Mosquito Lagoon region in Volusia and Brevard Counties, includes part of the Merritt Island National Wildlife Refuge (MINWR) which borders Mosquito Lagoon.

NOTABLE FEATURES WITHIN MLMA.

The fact that most of the MLMA marshes are publicly owned (as part of the MLAP, the CNS or MINWR, makes this management area unique among the 10 management areas delineated. Because so much marsh property, in particular within the CNS is not impounded presents opportunities for management other than the more typical Rotational Impoundment Management employed in many impounded marshes along the lagoon. Also, Ponce Inlet provides a tidal exchange between the Atlantic Ocean and the north portion of this lagoonal management area. Development is minimized along this management area and because so much of the area is publicly owned, future development pressure in many areas is limited. The Mosquito Lagoon marshes are typically vegetated with Salicornia spp. (glasswort), Batis maritima (saltwort) and Distichlis spicata, with occasional Avicennia germinans (black mangrove) and Laguncularia racemosa (white mangrove). In contrast, in southern regions of the Indian River lagoon, marsh vegetation is often dominated by mangroves.

VOLUSIA COUNTY COMPONENT OF MLMA.

In Volusia County, the MLMA includes 10 impoundments totalling 1878 acres part within the CNS (C-8, D-2, D-12N, D-12S) and the others in the MINWR (V1-V5 & T45 (which straddles the two counties)). Also included are several unimpounded marshes, largely within the CNS.

IMPOUNDMENTS.

The 10 MLMA impoundments in Volusia County are currently managed in a variety of ways. The CNS impoundments include: 1) Open Marsh Water Management (OMWM) with and without rotary ditches, 2) an impoundment connected to the lagoon through culverts and 3) one totally unmanaged (this includes no use of mosquito larvicides on the marsh)and 4) one larvicided on a need basis. Four of the six MINWR impoundments (V1-V5) currently maintain culvert connections to the lagoon with little other management. Six more culverts will be installed in this group of impoundments in the future.

UNIMPOUNDED MARSHES.

The unimpounded marshes within CNS include both unditched and previously ditched marshes some of which currently require periodic larvicide treatments to control salt-marsh mosquito populations.

BREVARD COUNTY COMPONENT OF MLMA.

In Brevard County, the MLMA includes 18 impoundments (T27A-T45) totalling 5450 acres. Management of this large acreage, which is along both sides of the lagoon within the MINWR, is split with approximately half of the impoundments being largely unmanaged with only an occasional larvicide application, and the others maintained with elevated water levels.

Management Plans

General Comments:

Many of the impoundments in this area are located within the Merritt Island National Wildlife Refuge. There are several unimpounded marshes in the area, particularly in Volusia County, and several impounded marshes remain open all year with mosquito control accomplished via OMWM.

The MINWR presently operates under the mandate of providing habitat and food for migratory birds and waterfowl. As such, management of many of these impoundments revolve around production of food plants and provision of suitable resting and foraging habitat for these birds; however, more emphasis on "ecosystem management" is probably forthcoming. A fall/winter drawdown schedule, alternating with years when impoundments are left open is the most common technique utilized presently for migratory bird management. However, management versatility is critical for achieving the stated goals. Refuge managers need the flexibility to alter the management of individual or groups of impoundments to cope with unpredictable weather conditions, and to maintain suitable habitat quality in these marshes.

Two factors presently limit the efficient management of many of the refuge impoundments: 1) Insufficient pumping capabilities, and 2) shortage of personnel to operate pumps and culvert gates. In the MLMA, the first problem could be resolved by installing a 36-inch pump in impoundment T-27A, which could be used to control water levels in close to 4,000 acres of impounded marshes. With pumping capabilities and additional field technicians, many of these impoundments could be opened sooner and/or closed later, thus maximizing the time where effective marsh-lagoon interchange is maintained. Obtaining funding for purchase and installation of said pump is important for this area, and for the lagoon as a whole.

Management of many of the MINWR impoundments under a fall/winter drawdown schedule limits the connections between marshes in this area and the lagoon, both in a temporal and a spatial sense. However, the management strategy for many of these impoundments includes periodic year-round opening, which should be staggered among sites so that some impoundments are open at any given time. Nevertheless, every effort should be made to maintain the marsh-lagoon connection in the remaining marshes in the area. Fortunately, many of the Volusia County impoundments can be managed under an OMWM strategy. These, together with the unimpounded marshes in the area, offer the best opportunities for balanced management.

Impoundment C-8. This impoundment is breached with rotary ditches and should be left as is.

Impoundment D-2. This impoundment receives a great deal of runoff from the uplands and is a good candidate for use as a stormwater retention area. The four existing culverts could be closed during high runoff periods, and/or riser boards installed to control discharge into the lagoon.

Impoundment D-12N. This is an isolated insular impoundment whose main water input is from rainfall and groundwater. As a result there is a proliferation of cattails and duckweed. This marsh could be best managed as an OMWM system with breached dikes. Prescribed burning may be necessary to eliminate some of the unwanted vegetation.

Impoundment D-12S. This marsh can be kept open all year if more ditches are constructed to eliminate mosquito breeding.

Impoundments V1 to V5. These relatively isolated and shallow impoundments are prolific mosquito producers. Additional ditches and internal culverts are needed to improve water circulation, minimize drainage, and to maintain and disperse larvivorous fish. Water circulation may also be improved with external culverts, but the shallow topography and a lack of natural conduits for water to the marsh interior severely limit the locations where the latter would be effective. With the above modifications, the impoundments can be left open all year.

Impoundment T-45. This impoundment can also be left open all year if more ditches are added for mosquito control.

Impoundments T-44 to T-38. This and the next group of impoundments form the core of the migratory bird/waterfowl management sites for this area. As such, management of these impoundments should consist of a mix of fall/winter drawdown, and open year round, with variations as needed for exotic control, sediment oxidation, etc. As mentioned in the general comments, flexibility is the key for successful management of these impoundments; specific schedules and timetables will have to be determined on a year-by-year basis, depending upon water levels, weather, marsh conditions, etc. Impoundment T-39S has been permitted for breaching by NASA, and others could conceivably also be breached in the future. More culverts are needed in the non-breached impoundments in this block for efficient water management.

Impoundments T-33C to T-27A. Management as above. A high priority for this group is the installation of a pump to allow efficient manipulation of water levels. One large (36-inch) pump installed at impoundment T-27A would allow proper control of water levels in the whole series of impoundments from T-27A to T-29B. Additional internal culverts (one 36-inch culvert each) connecting T-33A, T-33B, T-29A, and T-29B would extend the coverage of the pump to the T-33 group thus allowing proper management of 3,932.5 acres (1,573 ha) of prime overwintering habitat. In addition, pump installation will probably result in a longer open period for these marshes because managers will not have to depend upon tidal and rainfall trapping for flooding the area. Installation of the pump and culverts is considered one of the highest priorities on a lagoon-wide basis.


 

North Indian River Lagoon Map

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Area Description

The North Indian River Lagoon Management Area extends from the northern end of Indian River Lagoon at the Turnbull Creek marshes in Volusia County southward to the town of Cocoa on the Mainland Side and through the Shiloh and T-10 marsh impoundments on the east side on Merritt Island adjacent to the Indian River Lagoon. Most of the impoundments are a part of Merritt Island National Wildlife Refuge, and therefore publicly owned. Impounded marsh acreage is 18,024 acres with 283 acres in the 3 Scotsmoor cells 1512 acres in 3 Shiloh cells, and 16,229 acres in the other MINWR impoundment cells that are adjacent to Indian River Lagoon.

Unimpounded marshes stretch southward from the Scotsmoor area to Mims extending inshore to the FEC railroad tracks. Marshes are absent from Titusville southward to Cocoa on the mainland because of the relatively steep bank of the Indian River.

The major features of this area are the shallow waters of the Indian River Lagoon, which average about three feet depth through the entire lagoon cross section. Because of the shallow depth, seagrasses are abundant throughout the area. Fresh water is available to all impoundments in the area from Turnbull Creek, or from runoff from the mainland or Merritt Island. The Scotsmoor and Shiloh groups of impoundments are important features as well as the Haulover connection between the Mosquito Lagoon and Indian River Lagoon.

All the marshes are dominated by herbaceous halophytes because the area is too far north to support an abundance of mangrove vegetation. Because of distance from inlets the supply of juvenile fishes is probably limited, therefore waterfowl are a prime consideration in management planning. There are sixteen endangered species in the region. Two of these, the endangered wood stork and the threatened Atlantic saltmarsh snake, are the primary species affected by marsh management.

The Scotsmoor impoundments are herbaceous salt marsh, with freshwater aquatics. These marshes, as well as some in the Turnbull area are proposed for purchase by the St. Johns Water Management District and CARL. The SJRWMD is funding culvert installation in the Shiloh impoundments to control cattails and Brevard County is working with several private owners of the Scotsmoor Impoundments to engage in an innovative management plan that features a cyclic rotational impoundment management-waterfowl management plan.

Merritt Island National Wildlife Refuge manages its impoundments for several objectives including optimizing habitat for natural salt marsh, for wading birds, for overwintering waterfowl, or other wildlife benefits including fisheries.

Management Plans

General Comments:

This area encompasses some of the most valuable wildlife habitats in the MINWR. Parts of the NIRLMA are also in close proximity to human activity in the Kennedy Space Center. As with other impoundments in the MINWR, management flexibility is extremely important so that the refuge mission can be achieved while maintaining as much linkage between marshes and the lagoon as possible. To achieve the above goal, many water control structures (culverts and pumps) are needed in this area. Exotic control is also of high-priority in some of these marshes.

Impoundments Shiloh -1N, 1S, 3, 5. Water management within the Shiloh impoundments will alternate between drawdown and pump-up, but every effort should be made to leave them open as much as possible. These impoundments fall within an approved hunting area so water levels between September and mid-January may have to be maintained between 1.0 and 1.5 ft NGVD, at least in some of the cells. They can be flooded using portable pumps, but a permanent electric pump at Shiloh 5 is desirable to allow water level manipulations at all cells. Exotics are basically under control at cells 3 and 5, but additional control is needed in the others.

Impoundment T -21. This impoundment is also in a hunting area and is presently closed and managed independently from the Shilohs. The area is being encroached by cattails. Connection to the Shilohs with 6 culverts is advisable, and would solve the exotic problem. Should be managed like the Shilohs, but no pump is needed.

Impoundment T-9. This impoundment is partially breached, but water movement is inadequate. Total dike removal is recommended and is currently under way.

Impoundments T-18A, B. These impoundments require diligent mosquito control as they are in the vicinity of the Vehicle Assembly Building (VAB) and launch pads at the Kennedy Space Center (KSC). Initially, water levels need to be maintained up for at least one year (with periodic flushing) for exotic control. After that, the impoundments could be managed under RIM. Two culverts are needed 18B and four at 18A. With these modifications, both cells can be pumped through Impoundment 16.

Impoundment T-17. This impoundment is similar to the above, but requires 9 additional culverts for effective water management. Exotic control is needed initially.

Impoundment T-16. MINWR Management Strategy in concert with T-24D. Nine more culverts are needed at this site.

Impoundment C-20A, B, C. These impoundments are in a high waterfowl usage area, but also near high human use areas of the KSC, they should eventually be managed under RIM or under MINWR Management Strategy. The area needs one to two years of flooding with periodic flushing for exotic control. Culverts are needed at all three cells to increase flushing and circulation as follows: C-20A, 18 culverts; C-20B, 8 culverts; C-20C, 11 culverts.

Impoundments C-15B to C15-E, and Moore Creek. This area is similar to the above (high waterfowl use, near human activity). This is a large area with a serious exotic problem. Water circulation is wind driven and it receives high fertilizer inputs from nearby groves. A large (4 x 32 ft) box culvert is needed at the mouth of Moore Creek (north end). Installation of additional culverts will allow more flexible water management so that fertilizer loads can be retained or flushed as needed and blooms of undesirable vegetation can be prevented. The C impoundments should be externally connected to Moore Creek and internally with each other. With these modifications, the impoundments could be managed for retention or flushing with no need for pumping anticipated. Culvert needs are as follows: C-15B, 7; C-15C, 24-30; C-15D, 14; C-15E, 10. Control of Brazilian Pepper is a high priority at C-15C and C-15D as this exotic species is rapidly proliferating at these sites.

Impoundment C-15CB. This impoundment needs external culverts, and culverts connecting the area east of the south end of Moore Creek and south of C-15E to the marsh and to Moore Creek. To be managed as part of the above block.

ImpoundmentS T-1, 3, 4 (Scottsmoor). This is a high fisheries use area, particularly the North cell, where thousands of juvenile tarpon and other species are often observed. However, this cell is privately owned as is used as a for-profit hunting area. Purchase of this area is of very high priority. Exotic control is on target and is almost 90% complete in some areas. A cyclical management plan has been prepared for these impoundments by the Brevard Mosquito Control District (BMCD). It would be very beneficial if funding could be allocated to conduct a study evaluating the results of this plan upon physical conditions at the site, and upon mosquito production and non-target flora and fauna.

Impoundment T-24D. This is the largest single impoundment in the MINWR, covering approximately 3,000 acres (1,215 ha). The marsh is under severe invasion by cattails and some form of control is urgently needed. The marsh is relatively high, and may be left open except during the hunting season. Fourteen culverts were installed duirng 1995, but because of the high elevation, regular burns may have to be scheduled for exotic control.

Impoundment C-21:36. This area is heavily used by waterfowl and management should continue under MINWR Management Strategy together with C-20B and C-20C. The area is under heavy cattail invasion. It needs re-connection to the Lagoon with nine culverts after a one to two year flooded period (with flushing) for exotic control.

Impoundments T-34 & T-35. These impoundments are also in close proximity to KSC launch pads and the VAB. It should remain under RIM after a one to two year high water period with flushing for exotic control. Two additional culverts are needed at each impoundment to improve flushing and circulation.

Impoundment T-37A to T-37C. These impoundments are managed by NASA. T-37A is used for filtering pre-treated wastewater from the VAB and as a result, cattails are taking over. Reconnection to the Lagoon is not advisable, but it may be beneficial to periodically pump water in from Banana Creek and let it evaporate on site for exotic control. T-37B and C receive runoff from KSC roads and pads and should remain closed. A strategy similar to the above for exotic control may also be advisable at these sites, but a small pump is needed if the area is to be flooded.

Impoundments T-10A to T-10M and T-24A to T24C. There are 3,882 acres (1,572 ha) of impounded marshes in this impoundment block representing some of the most valuable habitat on the MINWR. Included are some of the impoundments in the high visibility Black Point Wildlife Drive. Management plans for this block call for the installation of 107 culverts of which 62 are external and 45 are internal. An important feature of this impoundment block is a reservoir system west of SR 406 that retains freshwater runoff, but may also be pumped. Pump stations exist at T-24D, at T-10B,C (Titusville), and at the northwest corner of T-10M (Dummitt). A permanent diesel pump station has recently been installed at T-10J,K. Construction of two small levies (100' x 20' x 6') between T-10K and T-10I and between T-10I and T-10G has also recenly been completed and will allow more efficient water management as described below.

Specific water management goals for this block will be decided on a yearly basis. The modifications summarized above, however, will improve interchange with the Lagoon and enhance water management capabilities for waterfowl, wading birds and mosquito control. Additionally, the improved control over water levels will allow management for restoration of marsh vegetation, will allow for more frequent drawdowns, will improve stormwater runoff filtration and will permit more accurate control of salinity throughout the area.

With the proposed modifications, all pumps will be capable of contributing to flooding the entire system, including the reservoir. By manipulating pumps and culverts, water levels and salinity can be managed efficiently and water of the desired salinity may be pulsed through the entire system. Under ideal conditions, a net flow-through can be achieved.

 

Banana River Map

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Area Description

This area covers the Banana River in the northern Indian River Lagoon. It contains 10 impoundments covering 2578 acres in Brevard County, and 14 impoundments covering 1411 acres in the MINWR. A majority of the impoundments outside of MINWR are privately owned except C2 (county) and C3 and C34 (state).

BREVARD COUNTY COMPONENT OF THE BANANA RIVER MANAGEMENT AREA.

ImpoundmentS C2 and C34 are under RIM management, with experimental water level manipulations for wood storks taking place in the south cell of C2. The dikes of impoundments C3, 2, and 10 have been breached, whereas the remaining impoundments are unmanaged. Most of the impoundments in the area have been heavily influenced by fresh water input. A portion of Sykes Creek empties into impoundment C2, and impoundments 1-5, 10, and 11 were formerly flooded by free-flowing wells. The wells have now been capped, and these marshes are now flooded primarily by rainfall.

Vegetation in the impoundments reflects the fresh water influence, with species such as Typha spp. and upland exotics dominating many of the areas. Exceptions occur at impoundment C2, which has a significant herbaceous halophyte cover, and C3 and C34, where black mangroves predominate.

Major features of the area include the Sykes Creek Parkway, which runs east of impoundment 1 to the south end of C2, where it connects with Audubon Rd. ; the barge canal, SR528, and the 528 Causeway, which divide impoundment C2 into north and south cells; the Central Brevard Airport north of Impoundment 3; the 520 Causeway which crosses the Banana River north of C3; the Cape Canaveral Air Force Station; and the Kennedy Space Center at the northern limit of the management area. Part of Sykes Creek, empties into Impoundment C2, and Newfound Harbor divides the southern tip of Merritt Island into eastern and western halves, with land connections via the 520 Causeway, Sykes Creek Pkwy, and SR528.

Most of this area has been intensively developed except for some areas south of SR528, where approximately 50 ha of Batis-Salicornia marshes exists, and in the 1000-island area, near C34, where mangrove and herbaceous halophyte wetlands exists, mostly in islands within the Banana River.

MINWR COMPONENT OF THE BANANA RIVER MANAGEMENT AREA.

There are 14 impoundments within the MINWR covering 1411 acres (impoundments T-25B and T-25D are joined and listed as one). The T-28 impoundments are presently managed under RIM or under MINWR strategy 2, but could be managed differently if more culverts were available. Impoundments in the C-21 group are now closed all year and are being considered as potential dredge spoil sites. The T-25 group is being managed under MINWR strategies 1 or 2.

Management Plans

General Comments:

This area encompasses some of the most valuable wildlife habitats in the MINWR. Parts of the NIRLMA are also in close proximity to human activity in the Kennedy Space Center. As with other impoundments in the MINWR, management flexibility is extremely important so that the refuge mission can be achieved while maintaining as much linkage between marshes and the lagoon as possible. To achieve the above goal, many water control structures (culverts and pumps) are needed in this area. Exotic control is also of high-priority in some of these marshes.

Impoundments Shiloh-1N, 1S, 3, 5. Water management within the Shiloh impoundments will alternate between drawdown and pump-up, but every effort should be made to leave them open as much as possible. These impoundments fall within an approved hunting area so water levels between September and mid-January may have to be maintained between 1.0 and 1.5 ft NGVD, at least in some of the cells. They can be flooded using portable pumps, but a permanent electric pump at Shiloh 5 is desirable to allow water level manipulations at all cells. Exotics are basically under control at cells 3 and 5, but additional control is needed in the others.

Impoundment T-21. This impoundment is also in a hunting area and is presently closed and managed independently from the Shilohs. The area is being encroached by cattails. Connection to the Shilohs with 6 culverts is advisable, and would solve the exotic problem. Should be managed like the Shilohs, but no pump is needed.

Impoundment T-9. This impoundment is partially breached, but water movement is inadequate. Total dike removal is recommended and is currently under way.

Impoundments T-18A, B. These impoundments require diligent mosquito control as they are in the vicinity of the Vehicle Assembly Building (VAB) and launch pads at the Kennedy Space Center (KSC). Initially, water levels need to be maintained up for at least one year (with periodic flushing) for exotic control. After that, the impoundments could be managed under RIM. Two culverts are needed 18B and four at 18A. With these modifications, both cells can be pumped through Impoundment 16.

Impoundment T-17. This impoundment is similar to the above, but requires 9 additional culverts for effective water management. Exotic control is needed initially.

Impoundment T-16. MINWR Management Strategy in concert with T-24D. Nine more culverts are needed at this site.

Impoundment C-20A, B, C. These impoundments are in a high waterfowl usage area, but also near high human use areas of the KSC, they should eventually be managed under RIM or under MINWR Management Strategy. The area needs one to two years of flooding with periodic flushing for exotic control. Culverts are needed at all three cells to increase flushing and circulation as follows: C-20A, 18 culverts; C-20B, 8 culverts; C-20C, 11 culverts.

Impoundments C-15B to C15-E, and Moore Creek. This area is similar to the above (high waterfowl use, near human activity). This is a large area with a serious exotic problem. Water circulation is wind driven and it receives high fertilizer inputs from nearby groves. A large (4 x 32 ft) box culvert is needed at the mouth of Moore Creek (north end). Installation of additional culverts will allow more flexible water management so that fertilizer loads can be retained or flushed as needed and blooms of undesirable vegetation can be prevented. The C impoundments should be externally connected to Moore Creek and internally with each other. With these modifications, the impoundments could be managed for retention or flushing with no need for pumping anticipated. Culvert needs are as follows: C-15B, 7; C-15C, 24-30; C-15D, 14; C-15E, 10. Control of Brazilian Pepper is a high priority at C-15C and C-15D as this exotic species is rapidly proliferating at these sites.

Impoundment C-15CB. This impoundment needs external culverts, and culverts connecting the area east of the south end of Moore Creek and south of C-15E to the marsh and to Moore Creek. To be managed as part of the above block.

ImpoundmentS T-1, 3, 4 (Scottsmoor). This is a high fisheries use area, particularly the North cell, where thousands of juvenile tarpon and other species are often observed. However, this cell is privately owned as is used as a for-profit hunting area. Purchase of this area is of very high priority. Exotic control is on target and is almost 90% complete in some areas. A cyclical management plan has been prepared for these impoundments by the Brevard Mosquito Control District (BMCD). It would be very beneficial if funding could be allocated to conduct a study evaluating the results of this plan upon physical conditions at the site, and upon mosquito production and non-target flora and fauna.

Impoundment T-24D. This is the largest single impoundment in the MINWR, covering approximately 3,000 acres (1,215 ha). The marsh is under severe invasion by cattails and some form of control is urgently needed. The marsh is relatively high, and may be left open except during the hunting season. Fourteen culverts were installed duirng 1995, but because of the high elevation, regular burns may have to be scheduled for exotic control.

Impoundment C-21:36. This area is heavily used by waterfowl and management should continue under MINWR Management Strategy together with C-20B and C-20C. The area is under heavy cattail invasion. It needs re-connection to the Lagoon with nine culverts after a one to two year flooded period (with flushing) for exotic control.

Impoundments T-34 & T-35. These impoundments are also in close proximity to KSC launch pads and the VAB. It should remain under RIM after a one to two year high water period with flushing for exotic control. Two additional culverts are needed at each impoundment to improve flushing and circulation.

Impoundment T-37A to T-37C. These impoundments are managed by NASA. T-37A is used for filtering pre-treated wastewater from the VAB and as a result, cattails are taking over. Reconnection to the Lagoon is not advisable, but it may be beneficial to periodically pump water in from Banana Creek and let it evaporate on site for exotic control. T-37B and C receive runoff from KSC roads and pads and should remain closed. A strategy similar to the above for exotic control may also be advisable at these sites, but a small pump is needed if the area is to be flooded.

Impoundments T-10A to T-10M and T-24A to T24C. There are 3,882 acres (1,572 ha) of impounded marshes in this impoundment block representing some of the most valuable habitat on the MINWR. Included are some of the impoundments in the high visibility Black Point Wildlife Drive. Management plans for this block call for the installation of 107 culverts of which 62 are external and 45 are internal. An important feature of this impoundment block is a reservoir system west of SR 406 that retains freshwater runoff, but may also be pumped. Pump stations exist at T-24D, at T-10B,C (Titusville), and at the northwest corner of T-10M (Dummitt). A permanent diesel pump station has recently been installed at T-10J,K. Construction of two small levies (100' x 20' x 6') between T-10K and T-10I and between T-10I and T-10G has also recenly been completed and will allow more efficient water management as described below.

Specific water management goals for this block will be decided on a yearly basis. The modifications summarized above, however, will improve interchange with the Lagoon and enhance water management capabilities for waterfowl, wading birds and mosquito control. Additionally, the improved control over water levels will allow management for restoration of marsh vegetation, will allow for more frequent drawdowns, will improve stormwater runoff filtration and will permit more accurate control of salinity throughout the area.

With the proposed modifications, all pumps will be capable of contributing to flooding the entire system, including the reservoir. By manipulating pumps and culverts, water levels and salinity can be managed efficiently and water of the desired salinity may be pulsed through the entire system. Under ideal conditions, a net flow-through can be achieved.

 


 

Sebastian Inlet Map

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Area Description

The Sebastian Inlet Management Area extends from State Road 510 the Wabasso Causeway and bridge) in Indian River County northward to Hog Point in Brevard County. This north south distance is about 16 miles and includes all the salt marshes, mangrove swamps and impoundments on the barrier Island side of the Indian River Lagoon. There are many mangrove islands included in the management area. The western boundary is the Intracoastal Waterway. Most of the public and private lands have had individual impoundment management plans developed in the last three years since development of the Sebastian Inlet Management Area Regional Plan.

The major features of this area are the Sebastian Inlet and the St. Sebastian River, a freshwater source west of the area. The proximity of the inlet to all these marshes is important, especially for fishery options related to the abundant supply of organisms entering the Indian River Lagoon at this location.

There are two important wading bird rookeries in or near the Management Area; Pelican Island and Grant Farm Island. Both of these rookeries support the endangered wood stork as well as other colonial nesting wading birds. Pelican Island is the central focus of Pelican Island National Wildlife Refuge, administered by the Fish and Wildlife Service. Other publicly owned areas of importance are the Sebastian Inlet State Park, and Long Point county park.

There are 15 impoundments in the SIMA, two of which are breached and unmanaged. The total impoundment area in the SIMA is 1206 acres (488.5 ha). Most of these impoundments are in Rotational Impoundment Management, and the two nearest two Pelican Island have a special winter pump up and drawdown feature for wading bird feeding. About 340 acres (137.7 ha) of island marshes and mangrove swamps which are unimpounded, but most of these islands have been ditched in the past.

Management Plans

General Comments:

The development of plans for the Sebastian Inlet Management Area (SIMA) and their adoption by the Subcommittee on Managed Marshes in 1991 was the first effort at regional management plan development. This effort was initiated by Joseph Carroll, then with the U.S. Fish and Wildlife Service, acting as Chairman of the Subcommittee on Managed Marshes'(SOMM) - Working Group on Impoundment Management Planning. This concerted planning effort resulted in funding for plan implementation through cooperation between the St. Johns River Water Management District's SWIM Project and the Brevard and Indian River Mosquito Control Districts.

SIMA extends for approximately 16 miles from CR 510 in Indian River County northward to Hog Point in Brevard County and west to the Intracoastal Waterway. It includes all the salt marshes, mangrove swamps and mosquito control impoundments on the barrier island side of the Indian River lagoon as well as salt marsh islands (most of which have been ditched). SIMA's most notable feature is the Sebastian Inlet which is centrally located within this area. The location of the Inlet within SIMA is important, serving as an access point for an abundant supply of organisms entering the Indian River lagoon from the Atlantic Ocean. The St. Sebastian River is a major source of fresh water located due west of the Sebastian Inlet on the mainland side of the lagoon. Two important rookeries, Pelican Island and Grant Farm Island, influence wading bird utilization of marshes within SIMA. Pelican Island is the central focus of the Pelican Island National Wildlife Refuge (PINWR).

Other publicly owned areas within SIMA are the Sebastian Inlet State Park (located in both Brevard and Indian River Counties) and Long Point County Park (Brevard County). There are 15 impoundments within SIMA totalling 1,206 acres. Many of the impoundments are under RIM (or targeted for RIM). Indian River Impoundments #2 & #3 are under a cyclic winter pump-up and spring draw-down schedule for wading bird enhancement. These impoundments were chosen for this use because of their close proximity to Pelican Island and because of the documented benefits this management technique can provide. Approximately 340 acres of unimpounded island marshes and mangrove swamps occur in SIMA, most of which have been ditched in years past but still require frequent larviciding to control salt-marsh mosquito populations originating there.

Hog Point. Plans are underway to implement RIM in this 106 acre impoundment but property owner approvals are pending. Currently this impoundment is closed, not pumped and has migrated largely toward a freshwater system.

North Grove. Plans to implement RIM in this 57 acre impoundment are also under development. Currently the impoundment is seasonally flooded with no lagoon connection.

North Siphon. This small 8 acre impoundment currently is open to the lagoon with 1 culvert. Adding another culvert is desirable to improve circulation and marsh-lagoon exchange.

John Smith. This 157 acre impoundment is currently under a RIM plan with a total of 7 exchange culverts. One more culvert is desirable. Public efforts to purchase part of this impoundment are under consideration.

South Siphon. This 16 acre impoundment is closed and not managed. Efforts to install 2 culverts are encouraged, but no capability to flood this impoundment exists, so an open connection should be maintained year-round.

Sunnyland. The Aquarina Development owns this 60 acre impoundment. Currently this marsh is seasonally flooded with a portable diesel pump but there is no connection with the lagoon. Plans for implementation of RIM are pending. When implemented, the plan will include 4 culverts and a permanent electric pump station.

Latham Hotel. This 27 acre impoundment, which is also part of the Aquarina property, is closed and not pumped. A long-term plan to open it with 4 culverts is being considered and should be implemented.

Nancy Creek. RIM is now employed at this 17 acre impoundment where 3 culverts have been installed. Pumping is accomplished with a portable diesel pump.

Long Point. This 150 acre impoundment is located within Brevard County's Long Point Park and is managed via RIM. It is flooded with a stationary electric pump and 8 culverts allow it to be seasonally opened to the Indian River Lagoon.

Campbell's Cove. This 68 acre impoundment, which is located within the Sebastian Inlet State Park, is RIM managed with a permanent electric pump and 4 culverts to allow seasonal marsh-estuary connection.

IRC #1 (Inlet). Located within the Sebastian Inlet State Park, this 153 acre impoundment is RIM managed. After RIM was designated as the desired management technique for this marsh in the initial SIMA draft, SWIM funding allowed for the purchase of culverts and a permanent electric pump station which were installed at this impoundment by the Indian River Mosquito Control District (IRMCD). Currently there are 5 exchange culverts and 2 bleed-down culverts.

IRC #2 (Bird's). Bird's Impoundment, which totals 156 acres, is managed on a cyclic winter flooding/spring drawdown scenario to allow in alternate years, the enhancement of feeding opportunities for wading birds. The winter flooding/spring drawdown function is alternated yearly with IRC #3 (Pete's). In years when the impoundment is not managed for wading birds, a RIM technique is used. The SWIM program, with IRMCD participation, has installed 5 exchange culverts and 2 bleed-down culverts on the portion of this impoundment that is in public ownership (the western half). Additional culverts are desirable on the eastern half of this impoundment when property ownership conditions allow. Also, a portable diesel pump was purchased to be shared between this impoundment and IRC #3.

IRC #3 (Pete's). Pete's Impoundment, which totals 150 acres, is like IRC #2 in that it is managed on a cyclic winter flooding/spring drawdown scenario to allow in alternate years, the enhancement of feeding opportunities for wading birds. The winter flooding/spring drawdown function is alternated yearly with IRC #2 (Bird's). The SWIM program, with IRMCD participation, has installed 5 exchange culverts (with 2 bleed-down culverts scheduled for installation this winter). Also (as mentioned in the description of IRC #2 above), a portable diesel pump was purchased and is shared between this impoundment and IRC #2.

IRC #4 (North Deerfield). This 51 acre impoundment, which is privately owned, is breached in two locations and is a prolific producer of salt-marsh mosquitoes. Even though it is open to the estuary through breaches, improved circulation could be accomplished with culverts or additional breaches.

IRC #5 (South Deerfield). This 30 acre impoundment, like IRC #4 is privately owned, and breached in one location. It is also a prolific producer of salt-marsh mosquitoes. It is open to the estuary through one breach, but as with IRC #4, circulation could be improved with culverts or additional breaches.

 


 

Winter Beach Map

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Area Description

The WBMA lies in Indian River County beginning 4.5 miles south of the Sebastian Inlet and extends south for approx. 9 miles. This management area include marshes on both the eastern and western shores of the Indian River lagoon (IRL) and islands within it. There are 17 impoundments in the WBMA, with all of the impoundments (except #22), and much of the open marsh being privately owned.

NOTABLE FEATURES WITHIN WBMA

The fact that most of the MLMA marshes are privately owned has limited optimal management opportunities for this area. Development along the southern portion of the WBMA is considerable. Most of the marsh property is impounded with several of the impoundments under RIM management. Located near this management area's northern end is the Wabasso (CR 510) Causeway which to some extent restricts water movement. The WBMA includes the area of the IRL commonly referred to as the "Narrows" which is roughly equidistant from the Sebastian and Ft. Pierce Inlets and receives little or no oceanic flushing. The Main Relief Canal (at the southern end of WBMA) and the North Relief Canal (also near the southern end of WBMA and just north of the Grand Harbor Development) is within this management area which provides periodic pulses of freshwater from upland runoff.

Vegetation in impoundments within WBMA differ considerably among marshes. In some impoundments, Avicennia germinans (black mangrove), Rhizophora mangle (red mangrove), Laguncularia racemosa (white mangrove), or a combination of these dominate, while in others Batis maritima, Salicornia spp. , or Distichlis spicata dominate. Distichlis spicata occurs significantly only in a few mainland impoundments in the "Narrows". The Pelican Island National Wildlife Refuge (with an associated rookery) is nearby the northern end of the WBMA. Bird utilization of WBMA marshes is undoubtedly influenced by this close proximity to Pelican Island.

IMPOUNDMENTS

The 17 WBMA impoundments total 1452 acres and are currently managed in a variety of ways including: 1) Rotational Impoundment Management (RIM), 2) open through culverts, 3) breached, 4) Open Marsh Water Management (OMWM) with rotary ditches, 5) and flooded year-round.

UNIMPOUNDED MARSHES

The unimpounded marshes within WBMA include mostly previously ditched marshes along the IRL fringe and islands within the lagoon. These marshes total approx. 250 acres which greatly contribute to the salt marsh diversity of this Management Area. The largest of these unimpounded marshes are at the southern end of IRC Impoundment #6 (Pine Island) and a marsh just south of Quay Dock Rd. in Winter Beach proper.

North Winter Beach Marsh. This 79 acre mainland unimpounded marsh located just south of Impoundment #27S (Timinsky), has been heavily ditched and only on occasion produces mosquitoes. No change in management suggested.

Indian River Shores Islands. A number of islands (approx marsh acreage = 200 acres) at the south end of the Winter Beach Management Area and located just north of the Merrill Barber Bridge. The area regularly produces mosquitoes which require aerial treatment. These islands are a combination of spoil material (with dominant vegetation being Australian Pine and Brazilian pepper) along with a mangrove fringe. On some of these islands, marsh sloughs extend into their interiors. Many of them are densely vegetated with Brazilian Pepper making thorough inspection difficult.

South End of Pine Island. At the south end of Pine Island Impoundment an unimpounded marsh (approximately 88 acres). The area is heavily ditched and requires only infrequent treatment. There are also approx. 20 acres of upland spoil within this area.

Johns Island Marsh. This 39 acre marsh which is nearby Water Tower Impoundment, at one time was an impoundment the western dike was removed as part of a canal construction project. This marsh is now totally intertidal and requires occasional treatment.

Management Plans

General Comments:

The Winter Beach Management Area (WBMA) ranges a little over 8 miles, essentially from CR 510 in Wabasso south to Vero Beach's Merrill Barber Bridge. This area includes 16 impoundments (totalling 1,446 acres), an Open Marsh Water Management system at Grand Harbor development, as well as some unimpounded marshes on the mainland, and on islands within the lagoon. The 16 impoundments are currently managed in a variety of ways, including RIM, year-round flooding, not flooded and open all year through culverts, and breached with frequent larviciding. Several of these marshes are unique in Indian River County because of the presence of Distichlis spicata (salt grass). Many of the marshes within the WBMA are candidates for management improvements as discussed below. All proposed management improvements in this area include the removal of exotics along the dikes.

Impoundment #30A (North Vickers). This 45 acre, 3 cell impoundment is the northernmost mainland impoundment until reaching Northern Brevard County. At the property owners request, the impoundment has been kept flooded year-round for their fish stocking interests. Over the past year or so, water from the adjacent grove has been diverted through the impoundment to minimize direct impacts to the IR Lagoon. Currently, there is waterfowl utilization of the north and middle cells. Because the impoundment has remained constantly flooded for many years, it is not a salt-marsh mosquito producer.

The management strategy proposed for this 3 cell system is a modified RIM plan. It is proposed that the north and middle cells continue to serve a waterfowl management role with overflow agricultural water continuing to be channeled through the impoundment. Limited lagoonal connection in the north and middle cell is proposed (1,30" flapgated exchange culvert in each of the two cells), which will connect them to the lagoon yet still allow them to continue to serve as waterfowl habitat. The southernmost cell should receive 3-5 culverts thus allowing it to seasonally connect the impoundment with the lagoon. A permanent electric pump is highly desirable. The adjacent citrus grove property is an excellent candidate for development making this impoundment a strong mitigation candidate. Maintaining a less than full-RIM strategy here is appropriate because of the large acreage of unimpounded marsh and breached impoundments in the adjacent Sebastian Inlet Management Area. Providing some waterfowl habitat is important in that this area provides for a stepping-stone corridor for migrating waterfowl. Beginning with the Scotsmoor impoundments in northern Brevard, followed by North Vickers, Vista Royale, and then St. Lucie County, a series of fresh water marshes are available as feeding, resting and overnighting stops for waterfowl. This is a positive factor in creating diversity in the Management Area.

This impoundment is the only wetlands on the mainland between County Road 510 northward to north Brevard. The entire tract (including impoundments and the upland grove) is currently for sale. This tract is also due west of some of the mangrove islands that make up part of the Pelican Island National Wildlife Refuge. These factors should make this tract a high priority for public purchase and preservation. The upland grove area can be converted into a large stromwater treatment area for the U.S. 1 corridor, with the overflow being directed into the north cell of the impoundment for additional treatment.

Impoundment #30B (South Vickers). This 16 acre impoundment is currently open to the lagoon through (3) 36" concrete culverts and (1) 18" aluminum culvert. The concrete culverts are largely blocked due to siltation and provide little or no flushing. The 18 in culvert connects the marsh through a boat basin and provides the majority of flushing. The eastern dike of the impoundment is severely eroded in some areas which probably overwash during high tides. Over the past several years, this impoundment rarely has produced mosquitoes. The management strategy for this impoundment should be to maintain it in its open configuration and enhance connections and circulations by scraping down the eastern dike in several locations. In addition, the concrete culverts should be removed creating a shallow breach, and the area stabilized with vegetation. The area may have to be larvicided as needed for mosquito control.

Impoundment #29 (Morgans). Morgans is a 71 acre, 4 cell mainland impoundment with no connection to the lagoon. It has been seasonally flooded for mosquito control since its construction in 1961. Development is rapidly encroaching here, especially around the north cell which abuts CR 510. The management strategy suggested for this impoundment is a typical RIM plan. Approximately 10-12 culverts, a permanent electric pump station, and improvment of the inter-cell connections will be necessary for proper management.

Impoundment #28 (North Winter Beach). North Winter Beach Impoundment is a 72-acre, 3 cell mainland impoundment which has been seasonally flooded off and on for the past 30+ years. The southern half of the north cell has served as mitigation for the Copelands Landing project and now contains 6 exchange culverts and a pump station, allowing for limited RIM management of most of the impoundment system. The southernmost cell, unmanaged at the property owners request, is disconnected from the impoundment system and open to the lagoon through one 24-in diameter culvert. This southern cell requires occasional larviciding. The middle cell is flooded through interconnection with the north cell but has no direct connection to the lagoon.

It is suggested that this impoundment remain under RIM and that the culvert connection between the north and middle cells and the lagoon be improved. Additionally, 3-4 culverts are needed in the northern half of the north cell and 3-4 culverts in the middle cell. The plan calls for leaving the south cell open to the lagoon, with the possibility of incorporating it into the system at a later date should property owners allow it and a need arise. At that time, several culverts (2-3) would be installed there to allow for improved estuarine connection.

Impoundment #27N (South Winter Beach). This 30-acre mainland impoundment has not been flooded for the past 15+ years and is connected year-round to the lagoon through one 24-in culvert. This impoundment requires infrequent larviciding. This impoundment should remain open and several more culverts (2-3) should be installed to improve marsh-lagoon connection. An option to strongly consider for this impoundment is to divert run-off water from the adjacent grove through the impoundment. Currently a drainage ditch runs along this impoundment's north side and discharges directly into the lagoon. Water quality could undoubtedly be improved by first channeling the runoff through the impoundment.

Impoundment #27S (Timinsky). Currently this 47 acre impoundment is not artificially flooded and requires occasional larviciding during the mosquito season. Given the impoundment's narrow configuration and relatively high elevations, it is not a good candidate for future flooding. Therefore, the proposed management strategy is to improve marsh-lagoon connection through culverts or dike breaches, with the possibility of some selective ditching as needed. However, this area is extremely rocky, making the construction of ditches problematic. It is anticipated that continued larviciding of this impoundment will be necessary.

Grand Harbor. This 102 acre created marsh system is managed under Open Marsh Water Management (OMWM) using shallow (rotary) ditches to connect mosquito producing areas to deeper water habitats. No changes in the management strategy for this area are proposed.

Impoundment #26 (Triangle). A portion of this small, 16 acre impoundment is part of the Grand Harbor system therefore under OMWM. The remainder of it (approx. 10 acres) is isolated from Grand Harbor by a road and separated from the lagoon by a low dike. This area frequently produces mosquitoes which require treatment. The management strategy proposed here is to improve connection with the lagoon through breaches or culverts along the eastern edge of the impoundment and possibly connect it to the Grand Harbor OMWM system by culverting under the existing road on the impoundment's west side. Rotary ditching is suggested if a need is documented.

Impoundment #25 (Lab). Lab Impoundment (also known as Gifford Plots) is a 76 acre mainland impoundment which is breached in one location. It has 9 internal dikes running E-W, dividing the marsh into 10 areas, each roughly the same size. With only one breach and many internal berms, water movement within the marsh is greatly restricted. This impoundment was used for the early impoundment research conducted by Rogers and Clements at the Florida Medical Entomology Laboratory. This work documented the mosquito control benefits of impoundments. The dikes are largely overgrown with Brazilian pepper, consequently, the interior of the impoundment is not routinely inspected. Mosquito production is frequently documented along the impoundment's western edge which triggers aerial treatment of all, or a portion, of the impoundment.

The proposed management strategy for Lab Impoundment is to remove the 9 internal dikes, install culverts (3-4) connecting the impoundment to the lagoon, and monitor the impoundment for mosquito production. Because of the proximity of this marsh to rapidly encroaching development, closure of the breach and implementation of a full RIM plan may be necessary should the impoundment prove to be a large mosquito producer in the future.

Impoundment #24 (North John Knights). North John Knights is a 57 acre, breached impoundment which is one of Indian River County s (IRC) most prolific mosquito producers. It has been aerially treated as many as 14 times in one season. This impoundment is densely vegetated with Distichlis spicata, which is one of the few locations in IRC where this plant exists.

The approriate management strategy for this impoundment is to increase the marsh-lagoon connection with additional breaches and install rotary ditches as needed. Existing ditches should be cleaned out at that time. Also, the construction of deep water fish reservoirs with radial ditches would be an appropriate long-term goal here.

Impoundment #23 (South John Knights). South John Knights (44 acres), has not been flooded for 20+ years at the property owners request. It currently has one 24 in exchange culvert which has been kept closed for many years. Like N. John Knights, this impoundment is a prolific mosquito producer and contains dense beds of Distichlis spicata, especially in the impoundment's western portions.

The management strategy proposed for this impoundment is to increase the number of exchange culverts (adding 3-4). Passive RIM (retaining lagoon water with flapgates but without pumping) would be used to maintain some summer flooding with the goal of reducing pesticide use here.

Impoundment #22 (Golf Course). Impoundment #22 is a 90 acre impoundment which served as a mitigation site for Indian River County when the Indian River Boulevard was constructed. It currently is RIM managed, with 7 exchange culverts and 2 internal ones. Since the current RIM plan is working well, and much development is nearby and constantly increasing, no management change is proposed for this marsh.

Impoundment #9 (Sand Point). Sand Point is a 149 acre barrier island impoundment which is currently flooded during the summer months. For a 15+ year period ending in the late 1980's, this marsh was not flooded at the property owner's request and during that time was a prolific mosquito producer requiring frequent aerial larviciding. Since 1988, it has been flooded seasonally. Because of the close proximity of nearby development, RIM is the management strategy proposed for this marsh with the installation of 8-10 culverts. Because of its close proximity to homesites, a dedicated permanent electric pump is necessary to assure effective mosquito control.

Impoundment #8 (Water Tower). Water Tower is a 152 acre barrier island impoundment which, like Sand Point, is currently flooded during the summer months. For the same 15+ year period ending in the late 1980's, this marsh was not flooded at the request of the property owner and was a prolific mosquito producer. Since 1988, it has been flooded seasonally. Like Sand Point, it is near heavy development and RIM is the management strategy of choice. About 8-10 exchange culverts and a permanent electric pump are needed at this site.

Johns Island Impoundment. This 35 acre impoundment at the north end of the island in the Johns Island Development has 8 breaches and currently is not a mosquito producing problem. No management changes are proposed for this area.

Impoundment #7 (Hole in the Wall). This 130 acre island impoundment has been managed under RIM virtually every year since its creation in 1965. In several instances when the pump was not functioning properly and the marsh dried down during the summer months, it demonstrated the ability to produce mosquitoes in large numbers. Currently there are two 18 in diameter exchange culverts in it and the north dike is somewhat eroded but still functional. The management strategy for this impoundment is to increase culvert connection between the marsh and lagoon with approximately 8 culverts, stabilization of the north dike with fill and plantings, replacement of the aging electric pump, and removal of exotics on the center dike. IRMCD requests keeping the existing center dike as it serves as an inspection and flagging trail through the impoundment. Improvement of the under dike culverts would help facilitate water exchange between the two halves.

Impoundment #6 (Pine Island). This 320 acre impoundment was the first RIM mitigation project in Indian River County (in the mid-80's). As part of that project, an 11,000 gpm pump was installed along with nine 30 in diameter exchange culverts in the north of this impoundment. This system has functioned extremely well since its creation and continued RIM management of this marsh is appropriate. Installing additional exchange culverts (4-6) in the south of the impoundment would improve the seasonal marsh-lagoon connection.

Unimpounded Marshes. The only management change to be considered for unimpounded areas is the possibility of rotary ditching portions of the Johns Island Marsh (a former impoundment) should it be determined that such ditching would be of benefit.

 


 

Oslo Map

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Area Description

The Oslo Management Area's (OMA) northern boundary is located at the 17th Street Bridge in Indian River County (IRC) and extends south for approximately 11.5 miles to the northern portion of St. Lucie County (SLC). OMA includes marshes on both the eastern and western shores of the Indian River Lagoon (IRL), and islands within the lagoon. 22 impoundments occur in this Management Area. While most of these impoundments are privately owned, 2 are publicly owned with at least 2 more currently under serious consideration for public purchase.

NOTABLE FEATURES WITHIN OMA

As is the case with many of the 10 Management Areas, the fact that many of the OMA marshes are privately owned has limited optimal management opportunities in this area. Most of the marsh property is impounded with several of the impoundments under RIM management. The southern end of the OMA is near the Ft. Pierce Inlet which provides good oceanic water exchange especially for the St. Lucie County impoundments in the southern end of OMA. IRC's South Relief Canal (near the northern end of OMA) provides periodic freshwater pulses to the IRL.

IRC Impoundment #12 (located on the barrier island at the IRC/SLC border) and SLC Impoundments #23 & 24 served as study sites for the series of Coastal Zone Management studies during the 1980's which studied ecosystem effects of impoundment management practices. This research demonstrated the scientific validity of Rotational Impoundment Management (RIM) as a viable impoundment management technique providing source reduction mosquito control with natural resource benefits.

It is noteworthy that a joint purchase of 300 acres on the mainland side of the lagoon in and around IRC Impoundment #18 (Vista Royale) by IRC and the St. Johns River Water Management District is playing an important role in preserving and improving management of these resources which include an oak hammock, scrub hammock, tidal and impounded wetlands. A grant awarded by the Florida Inland Navigation District (FIND) will allow development of the educational opportunities for this area which is being called the "Oslo Riverfront Park".

Several miles south of Oslo Road in SLC, occurs several marshes which receive a considerable fresh water input from the uplands, in particular the sand ridge. Also along the west side of US 1 lies the "Savannahs", a freshwater habitat targeted for public acquisition.

On the eastern edge of the lagoon in SLC Impoundment #23 (which is State owned) abuts a large oak-palmetto hammock with considerable encroachment by exotic vegetation in particular Brazilian pepper (Schinus terebinthifolius). Several miles south of this lies Impoundment #19B which includes a fairly intact tropical hammock.

Vegetation in OMA impoundments differ considerably among marshes. In some impoundments, Avicennia germinans (black mangrove), Rhizophora mangle (red mangrove), Laguncularia racemosa (white mangrove), or a combination of these dominate, while in some other marshes, Batis maritima, or Salicornia spp. dominate. Several rookeries influence bird use in OMA. One is adjacent (but just outside) OMA to the north, the other is a spoil island off Oslo Road, the third within IRC Impoundment #13.

INDIAN RIVER COUNTY COMPONENT OF THE OMA

In IRC, OMA includes 13 impoundments totalling 779 acres with only Impoundment #17 (=133 acres) being publicly owned. Also included are approximately 150 acres of unimpounded marsh divided among the lagoon fringes and islands within the IRL.

IMPOUNDMENTS. The 13 OMA impoundments in IRC are currently managed in a variety of ways including: 1) Rotational Impoundment Management (RIM), 2) summer flooding only, 3) breached with larvicide treatments as necessary, 4) connected to the lagoon through culverts, 5) year-round flooding, 6) receiving secondarily treated wastewater (the only example we are aware of along the IRL; the possible impacts of this practice are unclear).

UNIMPOUNDED MARSHES. The unimpounded IRC marshes within OMA include marshes fringing the lagoon and several islands. The largest unimpounded marsh is where the South Relief Canal enters the IRL.

ST. LUCIE COUNTY COMPONENT OF OMA.

IMPOUNDMENTS. Impoundments 23, 24, 19B, 19D, and 21 are primarily estuarine systems managed in a variety of ways, including RIM, tidal trapping, or breached. Larviciding is done frequently, especially in impoundments 23 and 24. Impoundments 23 and 24 are frequently used by wading birds, and 19B is very alluring to wading birds during summer drawdowns. These impoundments contain large stands of mangroves and saltwort.

Impoundments 14A, 14B, and 14C are basically fresh water systems with little or no connection to the lagoon. These marshes maintain a variety of fresh water fauna and flora, and provide forage and resting areas for mottled ducks, blue-wing teal, and a variety of wading birds. Water is provided to these marshes via rainfall, or by runoff and seepage from the coastal ridge system immediately to the west. A nearly pristine coastal hammock lies to the west of impoundment 14C.

Management Plans

General Comments:

This area is important for wading birds and waterfowl because further south mangroves begin to monopolize and eliminate the open space requirements of many species. Exotic vegetation control is important throughout the area but only the most urgent cases are mentioned in the impoundment descriptions. Priority for public acquisition is assigned to impoundments 11, 12 and 14-16 (Indian River County).

Impoundments 19 to 21 in Indian River County have potential to function as stormwater processing areas because of their location adjoining the city of Vero Beach. We have suggested such function for impoundment 19 because it presently receives outfall from a treatment plant that will cease operating within the next few years and therefore the marsh character is mostly that of freshwater wetland. Furthermore, a relief canal runs next to the marsh thus simplifying the logistics. Use of the other two impoundments for this purpose should be addressed in the future.

Impoundments 17 and 18 have unique educational potential. The University of Florida's Florida Medical Entomology Laboratory (FMEL) adjoining these impoundments runs an active educational program of which these impoundments are an integral part, the first as an example of a herbaceous halophyte marsh and the second of a mangrove dominated wetland. In the vicinity there are outstanding examples of hardwood hammocks, Florida scrub, and a pristine mangrove-herbaceous halophyte marsh, which together with the impoundment provide a unique cross section of important Florida habitats.

Impoundments 20 & 21. These two impoundments are interconnected and are presently managed by flooding during the summer for mosquito control. There are no exchange culverts and the impoundments maintain standing water during most of the year. They are close to populated areas and are heavy producers of mosquitoes. A RIM protocol is suggested for both of them. An appropriate number of culverts connecting the impoundments with the lagoon need to be installed. Because of their location and the surrounding drainage patterns, these impoundments have a potential for use as stormwater retention areas.

Impoundment 19. This impoundment has been receiving discharge from the Vista Royale treatment plant since 1976. It is anticipated that this plant will cease operation shortly. Because of the past history, the character of the impoundment is mostly that of a freshwater marsh. A drainage canal, carrying runoff from Vista Royal and U.S.1 runs along the south edge of the impoundment and is the only potential source for pumping into the impoundment when the treatment plant shuts down. Given that the area will probably remain fresh after the plant is closed, the impoundment will best be managed by using it as a runoff retention area. This can be accomplished by installing appropriate structures to divert the flow from the relief canal into the impoundment. Appropriate safety measures will need to be taken to handle water flow during storm events, and culverts will need to be installed in the impoundment along the lagoon to accommodate the water flow.

Impoundment 18. Management plans have been developed for this impoundment that incorporate RIM, modified for maintenance of freshwater in one of the cells. There is an important rookery offshore of the impoundment, and educational facilities (catwalks, observation towers, interpretative trails) are also being planned. The Florida Medical Entomology Laboratory (University of Florida - IFAS) adjoins the impoundment and also maintains public educational facilities. Every effort should be made to complete the educational facilities planned for this impoundment.

Impoundment 17. This is a breached impoundment with an outstanding mix of herbaceous halophytes and mangroves, and a permanent pond. The impoundment-lagoon connection needs to be improved through the addition of breaches or culverts, and by lowering portions of the dike to approximately 0.5' NGVD to resemble the natural berm existing in the area. Some rotary ditching may be necessary in the future to control mosquitoes, particularly along the upland edge.

Impoundments 14, 15, & 16. This is a system of three inter-connected impoundments. Vegetation is a mix of mangroves, herbaceous halophytes, and open areas. This block of impoundments can be managed on an alternating summer drawdown regime to obtain a diversity of benefits not attainable with a single management strategy, while maintaining mosquito control capabilities. We visualize a schedule of one- to two-week drawdown in each of the impoundments with the whole process repeated after the last impoundment is drawn down. Existing culverts connecting the cells need to be replaced with larger ones with risers, and the number of interconnecting culverts need to be increased (at least 2-3 between each impoundment). Exterior exchange culverts need to be installed, and two additional electric pumps will have to be dedicated to the system. Because of the potential benefits derived from proper management of this block of impoundments, purchase of the three is of high priority.

Impoundment 13. This impoundment consists of two cells divided by a road. It is presently flooded during the summer, but there are no exchange culverts with the lagoon. Culverts are needed along the lagoon so that a RIM protocol can be established. Also, better connections between the two cells are needed to increase circulation.

Impoundments 10A & 10B. Presently, 10A is flooded year round. The open canopy nature of this impoundment, and its proximity to the rookery near 18A make this a good candidate for summer drawdowns. However, drawdown levels must be carefully controlled to avoid objectionable odor problems for the nearby residents of The Moorings. Impoundment 10B is breached and should remain so. Better connections with the lagoon (more breaches) will probably aid in water exchange and circulation.

Impoundment 11. This is a large impoundment, with heavy mosquito production and located in close proximity to residential areas. It is presently flooded during the summer, but can not be reconnected at other times because of lack of exchange culverts. A battery of culverts are sorely needed along the western edge so that a RIM protocol can be established. However, multiple ownership, and lack of cooperation from several of the owners may preclude establishment of a proper RIM protocol. Purchase of this impoundment is also of high priority.

Impoundment 12. This impoundment is presently being larvicided to control mosquito production in numerous depressions and potholes. Vegetation is mainly herbaceous halophytes. There are many bare areas and several permanent and semi-permanent shallow ponds. Because of its structure, the impoundment is an important shore bird habitat, and steps must be taken to assure that the impoundment remains open. To that end, limited rotary ditching to eliminate breeding in potholes, and some maintenance of the shallow ponds are advisable. The impoundment also needs culverts on the west extension to promote water circulation. A great deal of our knowledge of impoundment biology was acquired during many years of research at this site. Because of this, its importance as a bird habitat, and its proximity to Round Island State Park, efforts should be made to purchase this impoundment.

Impoundment 24. This impoundment is similar to IRC #12 except that coverage by herbaceous halophytes and mangroves is much more complete. The area contains a large permanent pond and is traversed by a tidal channel that conducts water through the center of the marsh. The area contains several potholes that breed mosquitoes. Connection of these potholes to tidal water by rotary ditching or creating large permanent ponds at sites where potholes are most abundant is desirable. Otherwise, the same management strategy as in IRC #12 should be applied. If this impoundment and IRC #12 are purchased, a large contiguous tract could be created between Round Island Park and the state property to the south.

Impoundment 23. The dike in this impoundment is breached, and should remain so. Water exchange and circulation should be enhanced by adding more breaches to the dike. Scraping down the dike to resemble the natural berm would be desirable as long as the spoil is not used to fill the perimeter ditch, which is effective in providing circulation and water exchange with the lagoon. Many old ditches are present throughout the marsh and many of these are partially filled in, thus providing pockets for water accumulation and stagnation. These old ditches should either be filled in or opened. There is a hammock along the upland edge of this impoundment with unique native vegetation that should be protected. Exotic plant control is a high priority in this marsh.

Impoundment 19D. This island impoundment is breached. The dike should be removed as long as a suitable location for depositing the spoil can be secured. If the dike is not removed, the existing breach needs to be cleared, as it is presently filling in, and additional breaches should be created.

Impoundment 19B. 19B is large impoundment with heavy mosquito production near populated areas. It should remain under RIM.

Impoundments 14C, 14B, 14A, and 13B. These are basically fresh water systems with obvious connection to the upland Savannahs and are presently unmanaged. They support a wide variety of freshwater plant and animal species, and provide good feeding areas for ducks. Parts of the upland area adjacent to impoundment 14C contain a well developed maritime hammock which should be protected. We see no advantage in modifying these systems and their extensive freshwater flora and fauna. Some measure of cattail control, however, is urgently needed. Impoundment 13B should be reserved for research on management of these freshwater systems and on exotic control. Any desirable technique developed there would be directly applicable to the remaining impoundments in the group and to similar freshwater systems along the lagoon.

 


 

Ft. Pierce Inlet Map

fpi_map
Area Description

The Ft. Pierce Inlet (FPI) Management Area (FPIMA) includes several large mosquito impoundments which are presently under management (St. Lucie County Impoundment numbers 19A, 16A, 17A, 18A, 1, 2, 3, 4, 5, and 6) and several smaller impoundments which are not presently managed. Dominant terrestrial vegetation types are mangroves interlaced with areas of saltwort and mudflats. A majority of the mangroves were killed or severely damaged in the freeze of December 1989 but juvenile plants are rapidly recolonizing these areas. A very diverse tropical hammock exists on Impoundment 19B, adjacent to the FPIMA. Exotic plants (Schinus terebinthifolius and Casuarina sp. ) have colonized many of the dikes and some of the upland areas in this management area. Most impoundments have multiple culverts which aid in tidal exchange between the impoundments and the surrounding Indian River during unmanaged periods. This management area also contains several large mangrove islands (some up to several acres in size) which have never been modified for mosquito control and remain in a pristine state.

The Ft. Pierce Management area is transected by the Ft. Pierce Inlet. Because of the presence of the inlet, lagoonal salinities and temperatures tend to remain more constant than in areas more distant from the inlet. The less saltatory salinity and temperature regimes of the area coupled with the high species diversity of the inlet tend to give this management area a relatively high diversity of estuarine fauna. Dense seagrass beds in the Indian River, and tidal creeks and canals in the mosquito impoundments support a wide variety of marine life including tarpon, redfish and manatees. Many species of birds, reptiles and mammals occur throughout the area. The beaches on the ocean side of this management area serve as nesting sites for sea turtles.

The Ft. Pierce Management Area contains considerable urban development adjacent to the Ft. Pierce Inlet and for some distance north and south. Two causeways connect Hutchinson Island with the mainland. Jack Island State Preserve, Pepper Park, The Inlet State Park and John Brooks Park contain publicly owned land in this management area. Presently, St. Lucie County is negotiating for the purchase of an additional 330 acres of wetland adjacent to the John Brooks Park. If the county is successful in acquiring this parcel, about three miles of lagoonal shoreline will be under public ownership south of the inlet. This, in conjunction with the approximately 4 miles of shoreline under public ownership north of the inlet should form a relatively large block of protected wetlands.

Management Plans

General Comments:

This area is characterized by intensive water management for mosquito control and natural resources. Many of the impoundments in the area are managed under modified RIM strategies, with continuous pumping and bleeding of water through bottom water release culverts. Mid summer drawdowns are also part of the regular schedule for many of these marshes. Several parks and preserves (Jack Island, Ft. Pierce Inlet, John Brooks, Green Turtle) occur within the area and influence the selection of management techniques. An aggresive public acquisition program led by the St. Lucie Mosquito Control District has been operational for some time, but private ownership still limits the management options in some areas.

Impoundment 1. Several entities (public and private) own parts of this impoundment, which was the first mosquito control impoundment in Florida. There are management plans in place for the area, that includes a passive recreation, education, and conservation area (Bear Point Sanctuary) on the western half of this 639 acre impoundment. Part of the land is still under private ownership; owners want a mitigation bank rather than outright sale, and negotiations are presently under way between various entities to resolve the issue. There are also potential plans to use the eastern side of the impoundment for spoil deposition.

Presently the area is not being actively managed at the request of the property owners. A RIM or modified RIM strategy with drawdowns would be appropriate for the area once the ownership issues are resolved. Exotic removal and marsh re-vegetation are of high priority in the area, and thirty-two more 36" diameter culverts are needed for proper management. Areas of the dike fringing the lagoon are in bad condition due to erosion and will need some attention.

This impoundment is under heavy wading bird utilization (over 6,000 birds in one overflight (Jim David pers. comm.). Plans for the Bear Point Sanctuary call for the construction of several boardwalks, trails, an environmental education kiosk at the old diesel pump station, and facilities for fishing, hiking and biking. The education component of this plan should be strongly emphasized.

Impoundments 2 to 5. There are management plans in place for this group of impoundments on the barrier island side of the lagoon. The plans call for a modified RIM strategy with continuous pumping (flow through) during the closed period and summer drawdowns. Additional culverts (2- 3 each impoundment) are required in the area on the west side of A1A of impoundments 3 and 4 for proper water flow. The "uplands" behind impoundments 3 and 4 are heavily infested with exotics. Parts of this area were former wetlands that were hydraulically filled during the construction of A1A. Construction of several back ditches and exotic removal are recommended. The back ditches will enhance circulation, may reclaim some of the former wetlands, and may prevent exotic re-colonization.

Impoundment 5 needs five more culverts at southern end. There is little flow on that side between the present connection to Little Mud Creek. The new culverts should link the impoundment directly to the lagoon to avoid too much discharge into Little Mud Creek. An additional perimeter culvert is also needed on the east side of A1A as flow through the existing ones is unsatisfactory.

Impoundments 15A and 15B. These impoundments are breached and should remain so. Larvicide applications have not been necessary at these sites recently, but may be required in the future.

Impoundment 16A. This impoundment is within the Ft. Pierce Inlet State Park. The impoundment sits near an old inlet channel, consequently the substrate is very sandy and parts of the dike leak. The dike of the SW cell is fairly impermeable so this cell can be managed under a passive RIM (tidal trapping) with drawdowns every 30 - 45 days. The rest of the impoundment should be managed under a straight RIM protocol with no drawdowns (because of the leaks). If conditions allow, flow through RIM can also be implemented here. The NE portion of the impoundment is under private ownership, but is being purchased by the Ft. Pierce Port Authority. Five more culverts will be needed on that side when the sale is completed.

Impoundment 17A. This area is to be purchased as part of the Port of Ft. Pierce Phase I project mitigation. The dike has large unconnected stretches that will have to be culverted (6 more culverts) before an effective modified RIM (flowthrough with drawdowns) can be implemented.

Impoundment 17B. This impoundment receives heavy public use by visitors to Pepper Park. It is now open all year through 3 culverts. No changes in management are recommended.

Impoundment 17C. Also open all year through 2 culverts. Privately owned with residential development nearby. Impoundment appears to flush satisfactorily with no dead ends in the system. No change recommended.

Impoundment 18A. This area is highly used by recreational fishers. There are some fairly deep ditches that offer good fish habitat. The area drains well through the existing 10 culverts. Major pest problem in this area has been sandflies, which can be controlled by short- term (2 weeks) flooding followed by drawdowns starting in June and repeated twice per summer. Some water can be maintained in the ditches for sandfly control during the drawdowns by not opening all of the culverts at once. One more culvert is needed. Construction of several fishing platforms could enhance public enjoyment of the area.

Impoundment 18B. Major portions of this impoundment, mostly uplands, were converted into open water areas by the Army Corps of Engineers. Openings to the east, north, and west provide unrestricted access to these open water areas. The dike is breached in several spots and the area flushes well. No changes are recommended.

Impoundment 19A. This is a privately-owned impoundment bordering the Ft. Pierce Inlet State Park. Queen's Island, is currently being considered for public acquisition. The impoundment was formerly managed under modified RIM, but presently there is no active management at the request of the property owner. The area includes an upland hammock and a recently-discovered archaeological site. Efforts should be made to restore management to a modified RIM strategy (flow-through) with drawdowns (3 more culverts will be needed). Construction of internal trails opening to fishing platforms and marsh overlooks should be considered. Additonal access to the east for recreational users is needed, as presently the only access is through a private residential development.

Impoundment 20A. This is a small impoundment with one culvert that remains open all year. No changes are needed.

Impoundment 20B. This impoundment is near the Sands sewage plant and may receive some water from that facility during high flow periods. The culvert in the impoundment needs to be replaced a flow through it is now minimal. However, because of the impact from the treatment plant, it may be advantageous to restrict or eliminate flow into the lagoon until the North Hutchinson Island Treatment Plant begins operation and flow from the Sands plant stops. The culvert can be replaced at that time and flow to the lagoon restored.

Impoundment 21. The dike of this Impoundment is breached on the north and south ends. The impoundment contains many internal spoil banks that should be removed. Some leveling of the adjoining uplands will probably reduce the mosquito problem in the impoundment.

Impoundment 25. This marsh has been heavily ditched and there are some internal spoil banks. Infestation with exotics is a problem and should be addressed. The dike is breached. Internal spoil banks should be removed or breached and a further breach is needed on the west side of the external dike to improve circulation.

 


 

Jensen Beach Map

jb_map
Area Description

The northern part of the Jensen Beach management area consists of several large managed mosquito impoundments (St. Lucie County impoundments 6, 7, 8A, 8B, 8C, 8E and 9) and three unmanaged marshes (St. Lucie County Impoundments 10A, 10B, and 12 (= Martin County Impoundment 1A). Dominant wetland vegetation consists mainly of mangroves with some large areas (several acres) of saltwort on impoundment 10A. Impoundments 6 and 10A both contain areas of uplands which support both exotic (Schinus terebinthifolius and Casuarina sp. ) and native tropical and sub-tropical hammock vegetation. The 1989 freeze caused extensive damage to many of the mangroves in this management area but many plants have recovered and where mortality occurred, mangrove recruitment is high.

All of the mosquito impoundments in this management area have multiple culverts which increase tidal replication and water interchange with the adjacent Indian River during unmanaged periods. One of the unmanaged impoundments (10A) is breached by a 100 foot channel which allows for open exchange between the estuary and the marsh at all times. The Indian River adjacent to the Jensen Beach management area supports large seagrass beds and a relatively diverse estuarine fauna. The beach areas to the east of the mosquito impoundments serve as nesting areas for sea turtles.

Development impacts are high in this area with a nuclear power plant occupying part of the northern zone of the management area and considerable condominium and commercial development covering large parts of Hutchinson Island south of Impoundment 10A. Also within this area are some travel trailer resorts which have been built on dredge and fill areas in the Indian River. A golf course is located on the uplands on the northern part of Impoundment 10A. Two causeways connect the barrier island with the mainland south of the Martin County Line. A large portion of impoundments 10A and 9 and several public beach access are the only publicly owned land in the St. Lucie County portion of this management area. This property, coupled with the approximately 450 acres of wetland owned by Florida Power and Light are the only major tracts presently under protection from development.

Management Plans

General Comments:

Management of some of the impoundments in this area is influenced by activities at the St. Lucie Nuclear Power Plant. Some impoundments receive runoff from the plant, which limits the potential pollution to the lagoon, whereas education and vegetation recovery projects are in progress in others.

Many of the impoundments in the JBMA maintain significant marsh-lagoon connections when compared to other areas, and suggested management modifications emphasize enhancement of flushing and internal circulation. Seasonal drawdowns for wading birds is recommended for several impoundments presently managed under RIM. Priorities for public acquisition are assigned to the remaining portion of impoundment 10A still under private ownership, and to impoundment SLC-12/MC-A1.

Impoundment 6. This is a relatively low impoundment, with many open water areas in its interior. It is not well suited for drawdowns for wading bird usage as it is difficult to maintain sufficiently low water levels to make the habitat attractive. However, the many open water areas provide significant habitat for fishes and other aquatic organisms, and increasing access to these areas should be a priority. To this end, five to ten external culverts need to be added to the north side of the impoundment to increase access opportunities and to promote flushing and circulation as part of the current RIM management strategy.

Impoundments 7 and 8A. These impoundments offer a unique educational opportunity because of the interpretative trails and catwalks constructed by Florida Power and Light. RIM management can be continued without detracting from the educational potential of the area. Additional facilities would be extremely beneficial to increase the educational impact of the area. In particular, additional plant identification tags are needed. Also, larger signage, depicting the structure and function of tidal marshes and mangrove forests, and explaining the purpose, function, and management of impoundments are extremely desirable. These signs could be installed at one location in an open shelter/rest structure, or they can be spread throughout the trails. Additional bird observation catwalks on the east and west sides would also be beneficial. The area is secure because of restricted access and supervision by FP&L personnel, so investment in these educational facilities is relatively safe from vandalism.

Impoundments 8B and 8C. These two impoundments are prolific mosquito producers and should be kept under RIM. However independent pumping capabilities for the two cells are urgently needed as excessively high water levels are being maintained in impoundment 8C to allow flooding of 8B. This is necessary to allow water flow over a spoil ridge that separates the two marshes. Vegetation mortality is evident at 8C, partly due to the high flooding elevations. Installing a pump at 8B would allow proper flooding elevations at the two sites and vegetation recovery at 8C. Alternatively, the spoil ridge could be removed, but this area presently supports luxuriant mangrove growth which would be eliminated if the spoil is scraped away. Internal culverts, and limited rotary ditches may also enhance flushing and circulation throughout the cells.

Impoundment 8D. This marsh can be left open during most years. If mosquito production becomes a problem, it can be flooded for two to three weeks via tidal trapping and then reopened.

Impoundment 8E. Present management of this area consists of short term flooding (3 weeks per month) followed by a one-week open period. This strategy is being used to promote the recovery of mangrove vegetation. The three-week flooding period is necessary to provide salt water to the substrate, which otherwise would remain too dry for optimal mangrove growth, to control mosquito production, and also to avoid colonization by undesirable vegetation such as cattails and higher ground exotics. Provisions for off-season flooding for irrigation, exotic control, wading bird utilization, and protection against freezing should be maintained for this area.

Impoundments 8F, 8G. These impoundments are used as stormwater retention areas for the St. Lucie Nuclear Power Plant, a strategy that minimizes excessive runoff into the lagoon. They are small, isolated areas which can not be interconnected to cycle different management strategies in the group. It is desirable to maintain high profile vegetation in these areas to minimize bird utilization because of possible contamination with pollutants carried by the runoff.

Impoundments 8H, 8I. Can be left open unless mosquito production becomes a problem, in which case short term flooding (2-3 weeks) via tidal trapping can be used for mosquito control.

Impoundment 9. This marsh contains a number of small hammocks that should be protected. Exotic vegetation control is important. The area can be best managed under a modified RIM strategy, which includes several drawdowns during the summer for wading bird use.

Impoundment 9 Annex. Although management of this impoundment can be similar to the above, it needs to be managed as a separate unit because marsh elevations are significantly lower and therefore, water levels must be adjusted independently. Some mangrove and herbaceous halophyte plantings have been proposed for this area as part of a mitigation project.

Impoundment 10A. This impoundment is unmanaged except for a 40 acre portion in the northeast section, which is managed by tidal trapping through a single culvert. This 40-acre segment is separated from the rest of the marsh by uplands, and by a low east- west road constructed many years ago. Because of this isolation, this segment has been responsible for a large part of the mosquito production from this marsh. Tidal trapping is only partially effective in controlling the mosquito problem.

The rest of the marsh is relatively flat, and lies at an elevation of slightly less than 1 foot NGVD. As a result of the low elevation, the marsh is regularly flooded by tides, and mosquito production is not a major problem. However, there is an extensive network of old ditches that can cause a significant sandfly problem. The south portion of the dike is breached and penetrated by eight 30" culverts. The north portion has eight 36" culverts, but these are non-functional because of sand blockage. Unique tropical hammocks border the marsh on the east, and penetrate into the marsh at several locations.

Because of the diversity of habitats in this marsh, it is a good candidate for installation of boardwalks and nature trails. A pump, possibly solar-powered, needs to be installed in the 40-acre northeast section, to allow effective mosquito control via RIM. Flushing and circulation need to be improved in the rest of the marsh to ameliorate the sandfly problem. To this end, the plugged culverts need to be replaced, and the effectiveness of additional breaches needs to be explored.

Impoundment 10B. The dike in this impoundment is in bad condition, with two natural breaches and one non-functioning culvert. It should be left open but internal circulation needs to be improved by adding additional breaches and/or culverts, particularly at the north and south ends of the marsh.

Impoundment 10C. This is a small impoundment with a single 24-inch polyethylene pipe connecting the marsh and the lagoon. It can be left open all year. Some cleanup and access control are desirable as the area has sometimes been used as a trash dump.

Impoundments 11A and 11B. A low berm separates impoundment 11A from 11B. 11B is an open water area separated from the lagoon by a dike with a breach on the south end which should remain open. One culvert on the south side of the internal berm connects the two impoundments. An additional culvert is needed on the north end of the internal berm to foster circulation and flushing. Additional breaches on the 11B dike may also be desirable.

Impoundment 12/A1. Presently, this impoundment is open all year through 8 culverts. However, the area is a prolific mosquito producer and requires frequent larviciding. Pesticide use can be eliminated by establishing a RIM protocol. Elevation in this marsh is relatively low, and effective mosquito control may be effected by a shorter closed/flooded period than normal (portions of June, July and August). Property owner concurrence, however, is a problem and purchase of this tract is highly desirable. An electric pump (and pump station) would be necessary for implementation of RIM. Exotic vegetation control is needed in some areas of this marsh.

Impoundment A2A and A2B. The dikes in these two impoundments have been breached. Marsh substrates are relatively low and, therefore, the whole area receives frequent tidal flushing and need no further modification. The area east of A1A across from impoundment A2A has very poor flushing and is a prolific mosquito producer. Culverts under A1A are recommended to alleviate the problem.

Impoundment A3N. This previously isolated impoundment has recently been placed under a RIM protocol as part of an Indian River Lagoon National Estuary Program Action Plan Demonstration Project. A great deal of research has been undertaken in this marsh and in the adjoining lagoon, and regular monitoring of basic water quality variables is still under way. The Florida Oceanographic Society has constructed a series of catwalks throughout the marsh as part of their educational program, and additional catwalks and signage are being planned. Obtaining funding for completion of these projects is a high priority. RIM management should be continued. Provisions for education and research are also appropriate for this marsh.

 


 

St. Lucie Inlet Map

sli_map
Area Description

The St. Lucie Inlet Management Area (SLIMA) extends from the Stuart Causeway in the North, to south of impoundment G2 in Martin County. It contains four impoundments with a combined area of 295 acres. Impoundments E3, E5, and G2 are on the mainland side of the lagoon, whereas A3s is on the barrier island side. None of the impoundments are actively managed, and the dikes of E3, E5, and G2 are breached. The impoundment vegetation consists mostly of mixed mangroves, with some upland species and exotics occupying some of the higher marsh areas.

NOTABLE FEATURES WITHIN THE SLIMA. Major features of this area include the St. Lucie Inlet, the Stuart Causeway, SR707 (Bridge Rd. ), USA1A, and the mouth of the St. Lucie River. The Jupiter Inlet is south of the management area. Except for public lands, the area along A1A is heavily developed, with a mixture of condominiums and single-family developments (both permanent and seasonal residents) and small businesses. The mainland side contains mostly single-family homes and small businesses.

The St. Lucie Inlet State Park extends south from the inlet along the barrier island to Cove Rd. , near Peck Lake, where it adjoins the Hobe Sound National Wildlife Refuge (HSNWR). The area around Peck Lake contains some natural marshes on the east side, whereas the west was formerly impounded, but has slowly reverted to a semi-natural state, with only some remnants of the dike remaining.

There are three unmanaged impoundments within the HSNWR (F1-F3), two of which have breached dikes (F2 & F3). Vegetation is mostly mixed mangroves, and there are no pumps or water control structures associated with these impoundments. The HSNWR also extends south from impoundment G2 (south of Bridge Rd. ) on the mainland side with some interspersed residential development. The barrier island side on this part is almost completely developed with upscale single-family homes.

Further south, near the Palm Beach County line on the barrier island, is the Blowing Rocks Preserve. This area is operated by the Nature Conservancy as a conservation-educational area. Within the preserve there is an extensive network of old mosquito control ditches that link to Hobe Sound via culverts. Much of the original ditching was along the border of spoil piles created by the construction of the Intracoastal Waterway. These piles have been colonized by Casuarina, and needle fall has filled some of the ditches. During the 1970's, an attempt was made to reconnect some of the ditches that were closed off by shoreline drift, but appropriate depths for ditches and culverts could not be attained because in this area, the Anastasia limestone is very close to the surface. As a result, the system has closed again. Within the Preserve, the area east of A1A was effectively impounded by the construction of A1A and the Intracoastal Waterway.

There has been recent pressure by surrounding residents for some measure of mosquito control in the area. Both the Nature Conservancy and Martin County Mosquito Control desire to undertake renovation of the dormant, unmanaged system to provide environmental enhancement and effective mosquito control.

Management Plans

General Comments:

The SLIMA contains four impoundments that are all unmanaged. In the southern part of the area, the Indian River is very narrow and boat wakes have breached the impoundment dikes at several locations. The area is near the St. Lucie Inlet and there appears to be adequate flushing. There are three impoundments in the Hobe Sound Refuge that are also breached.

Impoundment A-3S. The dike in this impoundment is not completely breached, but has several low areas that overwash frequently. Mosquito breeding is only a problem at the southeast corner during periods of very low tides. Adding several breaches to the dike may improve circulation and reduce the mosquito problem, but limited rotary ditching to increase flushing of the southeast end may be necessary.

Impoundment E-3. The dike in this impoundment is almost totally destroyed. The remaining portions of the dike could be removed, but this does not appear to be necessary at this time as the area is narrow and flushes well.

Impoundment E-5. This is a small impoundment with several breaches in the dike. A tidal creek flows through one of the breaches and the whole area flushes well and does not constitute a mosquito problem. No changes are recommended.

Impoundment G-2. Erosion has breached the dikes of this impoundment and flushing is adequate. No additional breaches or dike removal appear to be necessary at this time.

Impoundments F-1 TO F-3. These impoundments (not on map) are part of the Hobe Sound Refuge. The dikes are breached and open. No changes are recommended unless required by the Refuge's management strategies.