NEFCO worked with the Alliance Water Treatment Plant staff to identify priority nutrient reduction areas for failing and non-existent septic systems, manure, sludge, and other agriculture applications, and poor riparian/watershed BMPs. NEFCO used water quality sampling data collected by Alliance Water Treatment Plant staff and existing secondary source data and research, and made assumptions based on land use per sub-watershed; in order to quantify nutrients, and prioritize the problem areas. Limited field reconnaissance was conducted to verify the observations made by the Alliance Water Treatment Plant staff regarding failed septic systems, agricultural runoff, fertilizers or manure observations, and storm drains inspected for dry weather discharge. With these data, based on assumptions on failing septic systems and over-application of fertilizer on agricultural fields, NEFCO was able to quantify possible nutrient loads per sub-watershed, and to look for correlations between those areas and sampling site results. With these results, NEFCO was able to prioritize nutrient reduction areas. These areas were mapped as 1) the lack of green infrastructure: vegetated riparian corridors, wetlands, and woodlands; 2) areas with failing and potentially failing septic systems; and potential agricultural areas in need of BMPs based on croplands and pastures, and known farming operations.
June 15, 2016