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Changes in Water Quality of Grand Lake St. Marys Watershed Following Implementation of a Distressed Watershed Rules Package
Author(s) -
Jacquemin Stephen J.,
Johnson Laura T.,
Dirksen Theresa A.,
McGlinch Greg
Publication year - 2018
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2017.08.0338
Subject(s) - watershed , manure , environmental science , kjeldahl method , hydrology (agriculture) , water quality , phosphorus , watershed management , nutrient management , nutrient , sediment , water resource management , nitrogen , agronomy , ecology , engineering , chemistry , computer science , geotechnical engineering , organic chemistry , machine learning , biology , paleontology
Grand Lake St. Marys watershed has drawn attention over the past decade as water quality issues resulting from nutrient loading have come to the forefront of public opinion, political concern, and scientific study. The objective of this study was to assess long‐term changes in water quality (nutrient and sediment concentrations) following the distressed watershed rules package instituted in 2011. Since that time, a variety of rules (e.g., winter manure ban) and best management practices (cover crops, manure storage or transfers, buffers, etc.) have been implemented. We used a general linear model to assess variation in total suspended solids, particulate phosphorus, soluble reactive phosphorus (SRP), nitrate N, and total Kjeldahl nitrogen concentrations from daily Chickasaw Creek (drains ∼25% of watershed) samples spanning 2008 to 2016. Parameters were related to flow (higher values during high flows), timing (lower values during winter months), and the implementation of the distressed watershed rules package (lower values following implementation). Overall, reductions following the distressed designation for all parameters ranged from 5 to 35% during medium and high flow periods (with exception of SRP). Reductions were even more pronounced during winter months covered by the manure ban, where all parameters (including SRP) exhibited decreases at medium and high flows between 20 and 60%. While the reductions seen in this study are significant, concentrations are still highly elevated and continue to be a problem. We are optimistic that this study will serve to inform future management in the region and elsewhere. Core Ideas Grand Lake St. Marys receives high nutrient runoff from crop and livestock agriculture. The watershed was declared distressed in 2011, and management priorities were implemented. Management priorities included a winter manure application ban and encouraged other BMPs. Reductions in TSS, PP, SRP, NO 3 − , and TKN were noted at all flows following the designation. This represents an important step toward improved water quality in the watershed.