Discharger Led TMDL Study for Findley Lake Watershed, Ohio (How to Get a NPDES Permit for a 303(d) Listed Water When the TMDL is Years Away)

Findley Lake State Park, located in Lorain County, Ohio, is operated and managed by the Ohio Department of Natural Resources (ODNR). Findley Lake, an impoundment of Wellington Creek, is located within the park. The lake is designated by the state as an exceptional warm water habitat for aquatic life. To increase park use, ODNR planned improvements to park amenities that would require increasing the permitted capacity of the wastewater treatment plant (WWTP) that serves the park's campground and discharges to Findley Lake. However, since both Findley Lake and Wellington Creek are listed on the State of Ohio's 1998 303(d) list, the Ohio Environmental Protection Agency (OEPA) indicated they would not revise ODNR's National Pollutant Discharge System (NPDES) permit to allow an increased discharge to the lake prior to development of a Total Maximum Daily Load (TMDL) for the lake.Since OEPA estimated developing a TMDL for Findley Lake and Wellington Creek was 10 years away, the state was amenable to ODNR sponsoring development of the TMDL. As a preliminary step towards development of a TMDL for Findley Lake, Limno-Tech, Inc. (LTI) conducted a watershed and water quality modeling study of the lake on behalf of ODNR. The TMDL study evaluated relative contributions of watershed sources to water quality conditions in the lake and examined the water quality benefits of various management options. Eutrophication was the primary water quality issue investigated. Watershed loads were estimated using both monitoring data and a unit area load approach in order to address uncertainty in the limited monitoring data. Water quality in Findley Lake was predicted for existing conditions with the steady-state eutrophication model, BATHTUB, developed by the U.S. Army Corps of Engineers for reservoirs. The BATHTUB model was also used to predict lake response under various management scenarios.Modeling results indicated that agricultural nutrient loads from the predominantly agricultural watershed and internal nutrient cycling far outweigh nutrient loading from the WWTP discharge and are the primary contributors to water quality impairment in Findley Lake. As a result, removal of the WWTP discharge would have little effect on water quality. In addition, complete elimination of watershed loads would still result in nonattainment of the designated beneficial use for the lake, due to internal nutrient cycling in the lake. In light of the study results, OEPA has agreed to revise ODNR's NPDES permit to allow increased WWTP capacity while maintaining the current discharge load, even though a TMDL has not yet been completed.This paper describes the development and application of the watershed and water quality models to the Findley Lake watershed for this discharger led TMDL study and presents results of the model calibration and water quality predictions for future management scenarios. A discussion of study results in light of the determination that no feasible alternative exists for meeting “full use” of the lake's designated beneficial use is also presented.