Middle St. Johns - Florida Department of Environmental Protection

146
Water Quality Assessment Report: Middle St. Johns
advisory for Lake Dorr recommending limited consumption of largemouth
bass, bowfin, and gar because of elevated levels of mercury.
Several of the headwater springs in the Wekiva system have recorded
dissolved nitrate concentrations (expressed as nitrogen) above 1 mg/L.
A recent study found that the nitrate levels in Wekiwa Springs were
1.92 mg/L; in Rock Springs, 1.620 mg/L; and in Seminole Springs,
1.41 mg/L (Toth, 1999).
Permitted Discharges and Land Uses
Point Sources. There are 60 permitted point source dischargers in
the Wekiva River planning unit. Of these, 39 are domestic wastewater
facilities, 18 are industrial wastewater facilities, 2 are concrete batch
plants, and 1 is a petroleum contamination cleanup site. Six facilities are
NPDES-permitted and discharge directly to surface waterbodies. Nine
facilities are permitted to discharge more than 0.100 mgd. The Altamonte
Springs/Swofford facility, permitted for the largest discharge at 12.50 mgd,
is a domestic wastewater plant and is NPDES-permitted. The remaining
8 point sources, with discharges greater than 0.100 mgd, are all domestic
wastewater facilities. Two of these, Wekiva Hunt Club (2.9 mgd) and
Seminole County Environmental Services/Northwest Regional (2.5 mgd),
are permitted under NPDES. Appendix G lists, by planning unit, the
permitted dischargers in the basin.
Eleven sites in the planning unit implement reuse plans, including
reuse for irrigation, reuse into percolation ponds, and public access reuse,
with at least 3.68 mgd being discharged for these purposes. Altamonte
Springs/Swofford provides treated wastewater effluent for irrigation, while
the city of Ocoee (domestic wastewater, permitted to 3.0 mgd) has public
access reuse plans. The Audubon Village Mobile Home Park (domestic
wastewater, permitted to 0.049 mgd) is classified as a wastewater reuse
facility, with discharge to 2 percolation ponds.
The planning unit contains 1 active Superfund site and 1 delisted
state-funded hazardous waste site. There is 1 closed Class I solid waste
landfill in the planning unit and no construction and debris landfills.
Under Chapter 62-524, F.A.C., Potable Water Well Permitting in Delineated
Areas, there are 21 delineated ground water contamination areas for
benzene and EDB.
Nonpoint Sources. Predominant land uses in the planning unit are
urban and built-up (29 percent), upland forest (22 percent), and wetlands
(20 percent). Other major land uses include agriculture (15 percent),
rangeland (17 percent), and water (5 percent). Barren land and transportation,
communication, and utilities make up approximately 1.5 percent of
total land use. These developed land uses can be associated with nonpoint
discharges of pollutants and eroded sediments. Appendix H provides a
detailed analysis of land use in the basin, by planning unit.
Much of the basin was developed prior to stormwater management
requirements. Development has caused increases in stormwater flow rates
and volumes, erosion of the riverbank and bed, sediment buildup, and
increases in the amount of pollutants going into the river (SJRWMD,
2001c). A study in the early 1990s predicted rapid growth in this area and