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Draft Indian River County Lagoon Management Plan Outline April 2019
<br />1.0 INTRODUCTION
<br />1.1 GENERAL OVERVIEW
<br />The health of the Indian River Lagoon (IRL) is facing several challenges. Some of these cha -nges are easily
<br />measured (such as nutrient and pollutant levels) while others are less tangible (reduction in heries production,
<br />reduced recreational values, reduced seagrass growth, presence of algal blooms, habitat de adation). Indian River
<br />County is seeking to identify measures that can be undertaken in a systematic approac o improve the ecological
<br />conditions, recreational value, and the overall health of the IRL for the benefit of wildli and the public.
<br />Based on current data, it appears there are several potential sources adversely • ecting the IRL in Indian River
<br />County:
<br />• Urban stormwater runoff, which is generated by rainfall on pervious .-nd impervious areas associated with
<br />development and picks up and transports nutrients from fertilizers d pet waste, as well as other pollutants
<br />including sediments, herbicides, and pesticides. Urban runoff al • includes sediment, litter, oil, grease, and
<br />other pollutants from Florida Department of Transportation (FOT) highways and local roadways.
<br />• Agricultural stormwater runoff, which occurs on agricult al land and carries nutrients from fertilizers,
<br />livestock waste, pesticides, and herbicides through the c.. nal system.
<br />• Excess fertilizer that is applied beyond what plants h. >e the capability to uptake. Due to the sandy soils in
<br />the basin, nutrients from excess fertilizer can enter e groundwater with little removal. This groundwater
<br />can recharge surface water in ditches, canals, trib'taries, or directly to the IRL.
<br />• Septic systems, both functioning and failing, ••ntribute nutrient loading to the groundwater. Traditional
<br />septic systems provide little nutrient remova and depending on the age of the system, density of septic
<br />systems, soils in the area, and proximity to surface waters, can contribute a large quantity of nutrients to
<br />groundwater that will ultimately discharge o the lagoon.
<br />• Biosolids are the solid, semisolid, or li%uid residue generated during the biological wastewater treatment
<br />process. Land application of Class B biosolids is allowed on permitted sites at controlled rates in
<br />accordance with Florida Departmeof Environmental Protection (DEP)-established site restrictions and
<br />site management requirements. •wever, Class AA processed biosolids are considered fertilizer and are
<br />not tracked when applied to Ian'. The extent of potential impacts of land application of biosolids is not yet
<br />known, which may mean biosds with high nutrient concentrations are being applied in the IRL watershed.
<br />• Organic material from the pland areas. This material can come from leaf litter, grass clippings, and
<br />sediment from constructi. . The organic material flows through canals and tributaries to the lagoon and
<br />causes a buildup of mu• along the lagoon bottom, typically in deeper, lower energy portions of the IRL.
<br />• Extensive canal syst
<br />other specials distri
<br />organic material, . d
<br />throughout the County. Many of these canals are located within water control and
<br />s. These canals convey stormwater runoff from agricultural and urban areas, fertilizer,
<br />other pollutants to the lagoon.
<br />• Muck build-up - ong the lagoon bottom. Muck creates an environment that is not conducive to seagrass
<br />and filter feed growth. Muck is defined as black, organic -rich (greater than 10% organic matter), mud -rich
<br />(greater tha 60% silt and clay), high water content (greater than 75% water by weight, greater than 90%
<br />water by v. ume) sediments. The muck also fluxes nutrients into the lagoon, adding the nutrient loading.
<br />• Atmosp ; ric deposition that falls on both the land and the lagoon itself: The sources of these nutrients are
<br />from p. er plants, cars, and other sources that burn fossil fuels. However, because of atmospheric
<br />conditi. � and weather patterns, not all the nutrients from atmospheric deposition are generated within the
<br />OTETRA TECH
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