Evaluation of Ohio's First Far-Field Total Maximum Daily Load Developed For The Maumee River Watershed To Address Phosphorus Loads To The Western Lake Erie Basin

According to EPA, nutrient pollution is one of America's most widespread, costly, and challenging environmental problems. Ohio's ongoing efforts to address nutrient issues in the Western Lake Erie Basin (WLEB) provides a good case-study of the scientific complexity, technical difficulty, and economic hurdles states face when tackling nutrient water quality issues. After a lengthy legal history, Ohio EPA is now in the process of developing a TMDL for the Maumee Watershed to address shoreline and open water impairments in the western basin of Lake Erie, caused by harmful algal blooms of cyanobacteria. This effort represents Ohio's first attempt at a far-field TMDL. Ohio's TMDL program has undergone significant revision since Ohio EPA last published a TMDL. In 2015, the Supreme Court of Ohio ruled that a TMDL must be promulgated as a rule prior to implementation in National Pollutant Discharge Elimination System (NPDES) permits as TMDLs establish new, binding standards of water quality. The heart of the case stemmed from the lack of meaningful stakeholder review as part of the TMDL process and the court further held that the rulemaking process (or equivalent) must be undertaken prior to submission of a TMDL to USEPA for approval. Ohio's new TMDLs are subject to administrative procedures including stakeholder involvement at five key stages of the TMDL development process: the project assessment study plan or quality assurance project plan, the biological and water quality report or equivalent, the loading analysis plan, the preliminary modeling results, and the draft TMDL. This far-field TMDL must consider the entire Maumee watershed and there is not a single project assessment study plan or biological water quality report documenting the significant monitoring and evaluation efforts that have occurred to date. To fulfill the first two steps of the TMDL process, Ohio EPA provided stakeholders with a list of existing documents that collectively fulfill the requirements of the first two stages. The documents included in the list had been made publicly available prior to the commencement of the TMDL process and have previously been subject to stakeholder review. In September 2021, Ohio EPA published the draft Loading Analysis Plan (LAP) which represents the first 'new' document shared with the stakeholders as part of the TMDL development process. The draft LAP confirms Ohio EPA will rely on the phosphorus targets developed for the GLWQA and use the existing conservative Mass Balance Model approach for modeling nutrient loads currently employed to fulfill the state's obligations under House Bill 64 (passed in 2015). The most recent nutrient Mass Balance Report (2020) shows annual average TP loads from the Maumee River to Lake Erie ranging from 1,268 metric tons in water year (wy) 2016 to 3,897 metric tons in wy 2019. The report indicates that less than seven percent of the TP is from point sources and three percent is from home sewage treatment systems. The remaining ninety percent is attributed to nonpoint sources, which include agriculture, urban and rural stormwater runoff, and instream phosphorus cycling. The report is required to be updated in 2022 and should include data from 2013 through 2021. Significant changes are not expected; however, it is possible that for some watersheds (including the Maumee) that there will now be sufficient data to fit statistically valid trends indicating directional change in phosphorus loads.
While the Mass Balance Model may be the best option currently available for TMDL development, it is not without shortcomings that may significantly impact the TMDL if not properly accounted for in the TMDL implementation plan. The most significant concerns identified by the stakeholders include the Mass Balance Model assumes no nutrient attenuation along the entire 137 miles of Maumee River. This assumption (along with the entire Mass Balance Model) has not been validated. Additionally, the model does not account for the role legacy phosphorus plays in the water quality impairments seen in the WLEB. The TMDL will need to include how Ohio EPA will identify, prioritize, and address legacy and excess phosphorus 'critical source areas' as chronicled by the Great Lakes Advisory Board (GLAB) in its August 2021 Draft Nutrients Workgroup Report. The draft report states that legacy phosphorus accounts for up to 80% of the load, suggesting that the principal actions the TMDL should focus addressing this legacy load. Unless legacy nonpoint 'critical source areas' of phosphorus (including DRP) are clearly identified, their impact quantified, and strategies to address them implemented, it will be impossible to determine the necessary and appropriate reductions for other sources of phosphorus, much less to do so in a fair and equitable manner. While the TMDL process is ongoing, what has become clear is that any far-field TMDL for the Maumee Watershed must be adaptive, equitable, and feasible. TMDL implementation will require substantial investment to stand a chance at solving the WLEB nutrient-related impairments. A well-defined, structured, adaptive management process is needed so that stakeholders can reach consensus on the priority actions that should be taken first that will achieve the desired outcome, the effectiveness of those actions can be assessed, and consideration given to the most-effective actions that should be taken next. Initial implementation actions should be targeted towards priority projects that have a high likelihood of effecting meaningful change. The implementation plan should recognize that greater reductions can be achieved by some point sources (relative to other point sources) and nonpoint sources (relative to other nonpoint sources across the different types of land uses) at lower cost than for others, and that projects in the lower sections of the watershed address the most critical source area and result in the most benefit to the lake. The total cost of implementing the TMDL is of critical importance to every public and private entity, including farmers, cities and counties, businesses, and the cost-share programs that will help fund implementation. It is essential that a process be developed to estimate the cost of the various TMDL scenarios that will be explored. It is also critical that Ohio EPA coordinate funding opportunities and strategies with other governmental stakeholders. If the cost exceeds available/affordable funding, then the TMDL will essentially be unimplementable. This paper evaluates the development of Ohio's first far-field TMDL. The analysis will provide point source and nonpoint source perspectives in moving the needle toward the 40% reduction (from 2008 levels) in TP load required in the GLWQA and report on progress toward developing a truly adaptive TMDL that can serve as a model for other nutrient-impacted waterbodies.