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• Contract #SD€09AA Ili. PROJECT OBJECTIVES: The Indian River County area of the Lagoon (from Sebastian Inlet to St. Lucie County) was designated as Segment 3 in the Lagoon's characterization report produced by the IRL National Estuary Program (NEP) in 1994. Segment 3, known as the South Central Indian River Lagoon basin, is further divided into 23 sub -basins. The largest pollutant loadings in this segment are contributed by the large basins than have been extended by ditching and major canal systems, as has occurred in Vero Lakes Estates, where ditching has been connected to a crural system and the south prong of the St. Sebastian River, Three Chapter 298 districts exist within [his segment. They are Fellstncre Farms (FFWCD), Sebastian River (SRW'+CD) and Indian River Farms (IRFWCD) water control districts. "these three districts are varied in land use and drainage characteristics, The highest loadings in lire South Central Indian River Lagoon segment occur in IRFWCD's sub -basins are due to the characteristics of this urban built -out area which utilizes extensive ditching and canal systems for drainage to the iRL. When compared to other segments throughout the IRL region, it was calculated abut Segment 3, specifically the IRFWCD and SRWCD are among tire highest area loading rates for the estuary. These high loadings are attributed to the intense agricultural uses or the combinations of urban and agricultural development in the area. The effects to [he IRL and the St. Sebastian River. from the IRFWCD discharges are obvious, as salinity values drop to about 26.0 ppl. near the Vero North, Main and South Canal outfalls. This part of the Lagoon has a small surface arca, so evaporation is reduced as well. Another example of the effect of the freshwater discharge into this segment is color. Wet season color values tare higher than dry season values by a factor of 3, indicating discharge of colored, tannin -laden waiters during wet season stormwater and groundwater flow. Total phosphorus values around the three Vero canal discharge points (South, Main and North canals), as well its at the St. Sebastian. River, the Fellsmere Canal and C-54, are substantially higher than elsewhere in the Lagoon. Total Kjeldahl nitrogen is also elevated in this portion of the Lagoon between Wabaasso and Vero Beach, indicating that this entire segment of the Lagoon may be affected by discharges from the Sebastian River and the Indian River 'Farms Water Control Districts. Activities proposed in COUNTY'S Surface Water Management Plan are expected to reduce solids, sediments, organic matter, fresh water and nutrients discharged from. COUN`l'Y's stormwater systems. These actions will influence Lagoon trends in a positive direction. To date, Pollutant Load Reduction Goals (PLRGs) have not been established for Ilse COUNTY area or for other waters in tine vicinity. In November 1992, COUNTY completed its Master Stormwater Management Plan for Vero Lakes Estates. This plan identified the problems at the subdivision and suggested several technical objectives to resolving the identified problems. The problem at Vero Lakes Estates is relatively easy to define. The Master Plan conveyed that the subdivision does not have adequaatc stormwater treatment and drainage. The identified drainage and water quality problems are caused by: • Inadequate drainage for alae subdivision as the result of a combination of low original design capacity and subsequent reduction of that capacity through lack of maintenance. f'agc 10 o1- 25