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TMDL NPS-IS Resources

Total Maximum Daily Load Report

Total Maximum Daily Loads (TMDLs) are developed as a tool to help restore and protect waterbodies where beneficial uses are impaired or threatened for aquatic life, recreation, public drinking water, or human health. The objective of a TMDL is to determine the loading capacity of a waterbody and to allocate the load among different pollutant sources. A TMDL identifies the links between the waterbody use impairment, sources of impairment and the pollutant load reductions needed to meet the applicable water quality standards. It serves as a roadmap for measures that can be taken to improve water quality.

Types of information available through this report: assessment of water quality impairment, causes and sources, waste-load allocations, load allocations, implementation plan.

The Integrated Report (IR)

The Ohio EPA Integrated Water Quality Monitoring and Assessment Report (also called the Integrated Report or IR) indicates the general condition of Ohio's waters and identifies waters that are not meeting water quality goals. The report satisfies the Clean Water Act requirements for both Section 305(b) for biennial reports on the condition of the State's waters and Section 303(d) for a prioritized list of impaired waters. For each impaired water, Ohio EPA prepares a total maximum daily load (TMDL) analysis. In cases where impairment is not related to a pollutant (e.g., habitat alteration,) an alternative restoration strategic effort can be prepared. The types of information available in the IR inclue: assessment unit attainment status, cause of impairment, and TMDL status. The data used to develop the report are available in a spreadsheet on the website or through How’s My Waterway.

Summarizes data from watershed surveys into an interactive map of watershed assessment units (HUC-12s), large river assessment units and Lake Erie assessment units. The IR and interactive map are snapshots taken every two years. More recent data may be available for a watershed in a Biological and Water Quality Report (or Technical Support Document).

Biological and Water Quality Reports

Ohio EPA conducts surveys in selected watersheds around the state. A biological and water quality survey is a survey of the biological, chemical and physical properties of surface waters to determine the appropriate beneficial use designations (aquatic life, recreation, human health and water supply) assigned in Ohio Water Quality Standards, evaluate water quality trends and determine if the water body is meeting the goals of the federal Clean Water Act.

The results from each survey are detailed in biological and water quality reports (BWQR). These reports summarize major findings and provide results from individual sampling locations. 

Types of information available: water body existing and recommended beneficial use designations, attainment status, causes and sources of impairment, detailed discussion of sampling locations, sampling data results.

Loading and Analysis Plans

A loading analysis plan (LAP) is a plan prepared by Ohio EPA that lists actions to be taken by the Agency for sampling sites found to be impaired for a beneficial use designation (aquatic life, recreation and public water supply). Actions may include development of a Total Maximum Daily Load (TMDL), follow up sampling, referral to another agency and/or no action, for example where the cause of impairment is natural. For those sites where the Agency is planning to develop a TMDL, the LAP contains the proposed modeling approach and water quality restoration targets for a watershed study area.

LAP development is relatively new, and are not available for all watersheds but can be found in in the “Supplemental Information” on specific watershed TMDL report links. 

Types of information available: Impaired assessment units, causes and sources of impairment, actions to be taken by the Agency to address the impairment. For watersheds with existing TMDLs, comparison of previous sampling results with new findings.

How's My Waterway

How’s My Waterway - U.S. EPA’s new tool provides water quality information at the community, state and national level. Ohio’s water quality information from the final 2020 Integrated Water Quality Monitoring and Assessment Report is included along with permitted discharger, drinking water and nonpoint source program grant project information on a 12-HUC watershed assessment unit (WAU) scale.