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EXHIBIT A Indian river County Muck Survey Title: Locating Organic -Rich Sediments (Muck) in Indian River County Indian River County Muck Survey - Phased sampling to locate muck deposits INTRODUCTION/BACKGROUND Anthropogenic changes to lagoon hydrology and nutrient loading over the past century have created conditions leading to the accumulation of muddy deposits throughout the Indian River Lagoon. Indian River Lagoon (IRL) mud, locally known as "muck," is anoxic and uninhabitable to seagrasses and benthic fauna (Fuller et al., 2021). Decomposition of organic matter contained in muck leads to releases (fluxes) of dissolved nitrogen (1) and phosphorus (P) to the overlying water that can contribute to the onset and proliferation of algal blooms and trigger positive feedback loops that can sustain or worsen eutrophication (Fox and Trefy, 2018; Kemp et al., 2005). In some sub -basins of the IRL, muck contributes up to 40-50% of the total N and P loading from all sources including runoff, direct discharges and atmospheric deposition (Tetra Tech, 2021; Fox and Trefry, 2018). Muck management has thus become an important part of restoration plans for the lagoon system and selection of optimal sites for mitigation can help select where treatment would be most cost effective with respect to decreasing internal nutrient loading thereby improving outcomes of restoration efforts. The purpose of this project is to locate muck throughout Indian River County and obtain preliminary data showing differences in composition and fluxes among major deposits. In Brevard County, benthic fluxes of nitrogen and phosphorus among deposits ranged by 20 -fold (Trefy and Johnson, 2019). By strategically selecting the highest fluxing deposits for restoration, it is thereby possible to maximize benefits towards nutrient removal while obtaining the largest possible TMDL credits (based on current draft credit guidance). Prior to conducting physical surveys, historical datasets and remote sensing techniques will be used to locate probable muck deposits for further investigation. A grand survey will focus on these areas while also investigating the entire lagoon within Indian River County at lower resolution. Up to 5 discrete muck deposits located during the grand survey will be evaluated in more detail better defining boundaries of the deposits and estimating annualized inputs of nitrogen and phosphorus from each deposit. Detailed surveys will be designed to capture the extent and composition of surface sediments in each deposit and determine the number of samples required based on pre -dredging TMDL credit guidance (based on draft guidance from FDEP). Currently, few data regarding the distribution of muck in Indian River County are available and it is difficult to predict the extent of muck and the need for further detailed investigations. Therefore, this initial phase (Phase I) of study may identify a need for further investigation of additional discrete deposits within Indian River County. 1