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.