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a <br />Exhibit' D" <br />IR Impoundment M Management Plan <br />May 1992 <br />5. SOIL TYPES. Our source of information on Indian River soils is the <br />U.S. Dept. of Agriculture's Soil Conservation Service. This USDA <br />report defines Impoundment #18 soils as "McKee mucky clay loam". <br />This soil is described -as "level and very poorly drained. -formed in <br />unconsolidated loamy or clayey tidal deposits and is inundated by <br />fluctuating tides twice a day .... Slopes are less than 1 percent". <br />6. HYDROGRAPHY. Long-term lagoon tidal information for Indian <br />River County is available from two sources - the Florida Medical <br />Entomology's Oslo Road records (from 1959-1981) and the U.S. Dept. <br />of Interior's records at the Wabasso Causeway (the southern extent of <br />the Sebastian Inlet Management Area). The FMEI_ records are from the <br />just outside the SE edge of Impoundment 18. Both tidal records <br />demonstrate similar trends (i.e., seasonal highs in the late summer/fall <br />with lowest water periods in the spring and summer) (Figure 7). Given <br />Impoundment #18 close proximity to the FMEL station, we expect those <br />tidal records to provide the most meaningful data for this site. <br />The Indian River Mosquito Control District's recent and proposed <br />flooding elevation is 1.8 ft NGVD. Our experience in this <br />impoundment is that flooding to this level is necessary to inundate the <br />many mosquito -producing hillocks at relatively high elevations. <br />7. WATER CHEMISTRY INFORMATION (See Figure #1 for sampling <br />sites, Table 1 a -c for data). On eight occasions between Jan. 25 & <br />April 25, 1992, dissolved oxygen (ppm), temperature (degrees C.) and <br />salinity (ppt) was measured at up to 11 locations. <br />The measurements show fairly typical temperature and dissolved oxygen .. <br />concentrations for the winter/spring months. However, note the low <br />salinities at virtually all impoundment locations (maximum <br />impoundment uy--an=11 ppt). The lagoonal canal, which skirts the <br />impoundment's north side is the water source for mosquito control <br />pumping and is nearly fresh (mean=1.3ppt). The canal receives input <br />from the Vista Royale development <br />Also of interest is an approx. 13 acre isolated freshwater pond along the <br />impoundment's western edge. Salinities in the pond averaged 1.0 ppt <br />8. STRUCTURES. <br />a. EXISTING. Currently there are no culverts in this <br />impoundment As mentioned, interior dikes are breached but no <br />breaches occur in perimeter dikes. <br />3 <br />