Baldwin County Wetland Conservation Plan - Alabama Department ...

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Baldwin County Wetland Conservation Plan Final Summary Document Depressional Functional Assessment Model 10 Total points; 4 Actual; 6 Bonus; 2 possible subtractions Functional Assessment Ranges: 50% Conservation Wetlands This functional assessment model will be applied to isolated wetlands. Questions of Function: Water Storage Question 1. Is the observed wetland one (1) acre or larger in size? Rationale: Wetland size was considered to be one of the most important factors in terms of water storage. As such, this variable has been weighted to consider wetlands of one (1), ten (10) or one hundred (100) acres in size. Wetlands of this size will have a significant water storage capacity and would be of higher functionality than smaller wetlands. Due to scale of mapping, an acre is approximately the smallest mapping unit which would consistently show up on the final map products and thus is the smallest area which was considered for this variable. This variable was identified remotely through digital National Wetland Inventory (NWI) data. Data Column: Acres_Rate; 1 point Question 2. Is observed wetland ten (10) acres or larger in size? Rationale: See question # 1. This question served as a bonus. Data Column: Acres_Rate; 1 point bonus (for a total of 2 in the column) Question 3. Is observed wetland one hundred (100) acres or larger in size? Rationale: See question # 1. This question served as a bonus. Data Column: Acres_Rate ; 1 point bonus (for a total of 3 in the column) Question 4. Does the adjacent land use (i.e. residential, commercial, industrial, transportation or mixed urban use) surrounding the observed wetland provide for overland flow of surface water into the wetland? Rationale: Impervious surfaces, found mainly in urban setting (including residential, commercial or industrial land uses), will increase the volume of surface water entering the wetland. Thus, a wetland surrounded by these land uses will be more likely to receive and store larger volumes of water. This variable was identified remotely through digital land use data from FEMA. Data Column: WS_LULC; 1 point 107
Baldwin County Wetland Conservation Plan Final Summary Document Question 5. Is the observed wetland free of ditches as indicated by the absence of the NWI “d” special modifier? Rationale: The presence of ditches significantly alters the hydrologic regime of a wetland and reduces its ability to hold and slowly release water to the water table or aquifer. Consequently, the functional capacity to store water is diminished. This variable was identified remotely through digital NWI data. Data Column: ditch; subtract 1 point Question 6: Is observed wetland inside the zone of influence (designated wellhead protection area for the 10 year time of travel capture zone) of a major groundwater pumping center (withdrawal rates of three to four million gallons a day)? Rationale: Depressional wetlands within the Project area depend partly on groundwater discharge for their hydrologic requirements. Proximity of a wetland to a groundwater withdrawal well, which lowers the groundwater level within the zone of influence, could affect the hydrology of a wetland by lowering the water table. A wetland within the zone of influence of a groundwater withdrawal well would be more likely to exhibit a reduction in the groundwater table and would thus store more water than a wetland outside the zone of influence of a large groundwater withdrawal well. Since this variable deals with a human-induced condition, a “no” response will not count against a particular wetland. Rather, it will serve as a bonus question allowing a wetland extra consideration if this variable applies. This variable was identified remotely through digital maps provided by the EPA. Data Column: wellhead; 1 point bonus Sediment/Toxicant/Nutrient Removal Question 1: Does the adjacent land use surrounding the observed wetland fall into one of the following land use categories: residential, commercial, industrial, transportation, mixed urban use or agriculture? Rationale: The assumption is that developed or agricultural lands which surround a wetland would increase the nutrient, sediment, and toxicant load (fertilizer, animal waste, polluted runoff) entering the system. Thus, a wetland in this position would have an increased opportunity to cycle nutrients and filter water exiting the system. Since this variable deals with the issue of opportunity rather than functional performance, a “no” response will not count against a particular wetland. Rather, this will serve as a “bonus” question allowing a wetland extra consideration if this variable applies. This variable was identified remotely through digital land use data from FEMA. Data Column: STN_LULC; 1 point bonus Wildlife Habitat Question 1: Is the observed wetland free from government maintained roads? 108
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The Baldwin County Wetland Conserva
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3.2.3.2. Acquisition of GIS data la
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. List of Acronyms 1. ADCNR........
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d. Executive Summary The objective
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Baldwin County Wetland Conservation
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