Total Maximum Daily Load (TMDL) and the 303(d)

What are TMDLs?

Section 303(d)(A)(1) of the Federal Clean Water Act (CWA) requires states to identify waterbodies that do not meet water quality objectives and are not supporting their beneficial uses. Each state must submit an updated list, called the 303(d) List, to the U.S. Environmental Protection Agency (USEPA) every two years for approval. In addition, the law requires states to establish priority ranking for water bodies on the lists and develop control plans, called Total Maximum Daily Loads (TMDLs), to address the impairment. A TMDL serves as the means to attain and maintain water quality standards (WQSs) for the impaired water body. CWA Section 303(d) and 40 Code of Federal Regulation (CFR) Section 130.2 et seq., specify the components and requirements of a TMDL.

If a State fails to develop a TMDL, or if USEPA rejects the State's TMDL, USEPA must develop one (CWA 303(d)(D)(2), 40 CFR 130.6(c)). Upon approval of the TMDL by USEPA, the State is required to incorporate the TMDL, along with appropriate implementation measures, into the State Water Quality Management Plan (40 CFR 130.6(c)(1), 130.7).

Integrated Report

The Integrated Report is the biennial reporting method used by the State in compliance with federal requirements to report on the status of its surface waters. The Integrated Report consists of the 305(b) Water Quality Inventory Report and the 303(d) List of Impaired Waterbodies, which together make up an assessment of all surface water bodies with categorizations determining what actions are required to protect or improve individual waters of the state. TMDLs are then developed as needed based on the categorizations in the Integrated Report. Each Integrated Report biennial cycle consists primarily of assessments from the three Regional Water Quality Control Boards that are identified "on-cycle" by a notice of solicitation.  Past and current Region 7 Integrated Reports when the Regional Water Board was on-cycle are provided one the Region 7 Integrated Report program page.  

Additional information about Integrated Reports is also available on the State Water Board’s Integrated Report program page.

TMDL Projects

TMDLs Under Development

Approved TMDLs

Public Participation

Data

The Regional Board utilizes a variety of data sources when considering changes to the 303(d) List or when developing TMDLs. Data sources include Toxic Substances Monitoring, monitoring data for regulated/unregulated discharges, and data from other local, state and federal agencies. The Regional Board prefers data that utilizes quality assurance/quality control procedures (QA/QC) that develop reliable water quality sampling results.

One major data source is the Surface Water Ambient Monitoring Program (SWAMP). SWAMP watershed characterization calls for dividing the Region into watershed rotation areas and conducting synoptic, tributary-based sampling each year in one of the areas. Over a five-year period, all the hydrologic units in the Region are monitored and evaluated. Permanent watershed sites are monitored monthly for conventional water quality parameters, and once during the year for sediment chemistry, bioaccumulation, and benthic invertebrate assemblages. In addition to the synoptic site selection approach, additional monitoring sites are established in each rotation area to provide focused attention on watershed and water bodies known to have water quality impairments. SWAMP utilizes QA/QC procedures to develop reliable water quality sampling results. Visit the SWAMP program page for more information. For information about data used for a specificTMDL, contact the staff person working on the TMDL

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