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
This project was developed as a TMDL alternative as part of the Palo Verde Agricultural General Order and addresses DDT and toxaphene impairments in the Palo Verde Outfall Drain and Lagoon. The Palo Verde Agricultural Order was approved by the Regional Water Board on May 15, 2019 and the associated TMDL a alternative is currently under review by the USEPA.
This TMDL is part of the Imperial Valley Agricultural General Order and will address PCBs, chlordane, chlorpyrifos, DDT, diazinon, dieldrin, and toxaphene impairments in Alamo River, Imperial Valley Drains, and New River.
This TMDL will address bifenthrin, cypermethrin, and lambda-cyhalothrin impairments in the New and Alamo Rivers.
This TMDL will address chloride, indicator bacteria, and toxicity impairments in the Alamo River.
This TMDL will address dissolved oxygen and nutrient impairments in the Salton Sea.
Approved TMDLs
The TMDL was adopted by the Regional Board June 27, 2001, approved by the State Board on February 19, 2002, approved by the Office of Administrative Law on May 3, 2002, and approved by U.S. EPA on June 28, 2002. The following documents are now available:
Regional Water Board
- Basin Plan Amendment
- Resolution No. 01-100
- TMDL Staff Report
- Appendix A - Soil Association Descriptions
- Appendix B - SWRCB Toxic Substances Monitoring Program
- Appendix C - Source Analysis Data and Calculations
- Appendix D - Load Allocation Calculations
- Appendix E - Silt TMDL Technical Committee
- Appendix F - Silt TMDL TAC BMPs
- Appendix G - Recommendations of the UCCE
- CEQA Checklist and Determination
- Natural Environment Study
The TMDL was adopted by the Regional Board on October 10, 2001, approved by the State Board on March 21, 2002. It was also approved by the Office of Administrative Law on March 23, 2002, and approved by U.S. EPA on August 14, 2002. The following documents are now available:
Regional Water Board
- Basin Plan Amendment
- Resolution No. 01-197
- TMDL Staff Report
- Appendix A: Historical Bacterial Concentrations for New River at International Boundary
- Appendix B: New River Fecal Coliform Results for 2000
- Appendix C: Infectious Agents Potentially Present in Raw Domestic Wastewater
- CEQA Checklist and Discussion
The TMDL was adopted by the Regional Board on June 26, 2002, approved by the State Board on November 19, 2002, approved by the Office of Administrative Law on January 13, 2003, and approved by U.S. EPA on March 31, 2003. The following documents are now available:
Regional Water Board
- Basin Plan Amendment
- Resolution No. R7-2002-0097
- TMDL Staff Report
- Appendix A: Soil Association Descriptions
- Appendix B: SWRCB Toxic Substances Monitoring Program
- Appendix C: Source Analysis Data and Calculations
- Appendix D: Load Allocations
- Appendix E: Silt TMDL Technical Advisory Committee
- Appendix F: TAC Recommendations for On-Field Best Management Practices
- Appendix G: Recommendations of the UC Cooperative Extension
- CEQA Checklist and Discussion
- Natural Environment Study
The TMDL was adopted by the Regional Board on June 21, 2006, approved by the State Board on April 18, 2007, approved by the Office of Administrative Law on August 2, 2007, and approved by U.S. EPA on September 24, 2007. The following documents are now available:
Regional Water Board
The TMDL was adopted by the Regional Board on January 19, 2005, approved by the State Board on July 21, 2005, approved by the Office of Administrative Law on September 8, 2005, and approved by U.S. EPA on September 30, 2005. The following documents are now available:
Regional Water Board
- Basin Plan Amendment
- Resolution No. R7-2005-0006
- TMDL Staff Report
- Appendix A - Silt TMDL TAC
- Appendix B - Source Analysis
- Appendix C - Allocations
- Appendix D - Implementation Plan
- CEQA Checklist and Determination
- Natural Environment Study
- Economic Impact Assessment
- Responses to Public and Peer Review Comments
- Staff Supplemental Report (9/14/04)
The TMDL was adopted by the Regional Board on May 16, 2007, with revision later adopted by the Regional Board on June 17, 2010. The TMDL was subsequently approved by the State Board on July 19, 2011, approved by the Office of Administrative Law on February 2, 2012, and approved by U.S. EPA on April 27, 2012. The following documents are available:
Regional Water Board
- Basin Plan Amendment
- Resolution No. R7-2007-0039
- Resolution No. R7-2010-0028
- TMDL Staff Report
- Appendix A: Mean Monthly Streamflows, USGS Gage 10259540
- Appendix B: Relationship between Bacteria Indicators and Flows
- Appendix C: Coachella Coliform DNA Analysis Source Report
- CEQA Checklist and Discussion
- Natural Environment Study
State Board Approval
- May 18, 2011 Notice of Opportunity to Comment
- Comments Received
- Response to Comment
- July 15, 2011 Division of Water Quality Request for Executive Officer Corrections
- July 18, 2011 Executive Officer Response to Division of Water Quality Request
- July 19, 2011 State Board Meeting Agenda
- Item Sheet and Draft Resolution
- State Board Resolution No. 2011-0030
Office of Administrative Law (OAL) Approval
CEQA Filing with the CA Natural Resources Agency
U.S. Environmental Protection Agency (USEPA) Approval
USEPA Approval LetterThe TMDL was adopted by the Regional Board on May 20, 2010. The TMDL was subsequently approved by the State Board on December 6, 2011, approved by the Office of Administrative Law on March 21, 2012, and approved by U.S. EPA on November 16, 2012. The following documents are now available:
Regional Water Board
- Resolution No. R7-2010-0011
- Basin Plan Amendment
- TMDL Staff Report
- Appendix A: New River Water Quality Objectives and Beneficial Uses
- Appendix B: Water Quality Data for the New River
- Appendix C: Monthly or Quarterly DO Concentrations Data for Agricultural Drains in the New River Watershed
- Appendix D: NPDES Permittee Information and Data
- Appendix E: Regional Board DO Data at Four New River Sampling Locations
- Appendix F: New River DO QUAL2K Model
- Appendix G: New River Third Party Cooperating Agencies and Organizations
- Appendix H: TMDL Model Scenarios
- New River CEQA and Environmental Checklist
- New River Natural Environment Study
- Public Review Comment and Response
State Board Approval
- September 16, 2011 Notice of Opportunity to Comment
- Comments Received
- Response to Comments
- November 21, 2011 Executive Officer Request to make minor, non-substantive changes to Basin Plan Amendment
- December 6, 2011 State Board Meeting Agenda
- Item Sheet and Draft Resolution
- State Board Resolution No. 2011-0061
Office of Administrative Law (OAL) Approval
CEQA Filing with the CA Natural Resources Agency
U.S. Environmental Protection Agency (USEPA) Approval
USEPA Approval LetterPublic Participation
The Colorado River Region tries to foster public participation during all phases of TMDL development to address as many technical and social issues as possible early in the process. Each TMDL project will have a unique approach to public participation dependent on the size of the watershed, the nature of the problem, who and how many interested parties or stakeholders emerge, etc. Public participation will at times take on one or more of these forms: occasional public workshops, regularly scheduled steering committee meetings, Technical Advisory committee meetings, Regional Board staff presentations at other organization's meetings, or written solicitations or request for comments sent by mail.
The public has the opportunity and legal right to review and comment on TMDLs before they are made a part of the Basin Plan. Essentially this means that the public has the opportunity to comment on Draft TMDLs in writing prior to Regional Board Hearings or verbally at Regional Board Meetings before a TMDL is adopted and implemented.
Bodies of water are listed as impaired after several steps. One of the steps is the review of information and/or data by Regional Board staff pertaining to a body of water. Regional Board staff will notify the public when the review process will occur, and publicly solicit information or data that would lead to a listing of a body of water.
This section provides other opportunities for the public to be involved in the TMDL process. If the section below is empty, this implies that no specific event is on the agenda in the near future. However, remember that the waters of the state belong to its citizens, and you are encouraged to participate in the process designed to protect this resource. Simply call the Regional Water Quality Control Board office and make inquiries to the staff person working on the body of water near you.
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
Questions or Comments
- Emma McCorkle, Senior Environmental Scientist
Email:
emma.mccorkle@waterboards.ca.gov
Phone: (760) 340-4521
Other Links
- United States Environmental Protection Agency TMDL
This is the USEPA TMDL site. It contains general information regarding TMDLs, as well as listed bodies of water across the United States. - California State Water Resources Control Board TMDL
This site provides general information regarding TMDLs, listed bodies of water by Region, as well as a questions and answers. - Clean Water Act Section 303(d)
This site provides the section of the federal Clean Water Act mandating TMDLs. - Public Notices
This site provides Public Notices of TMDLs by region in the state of California. - Political and Legislative Documents
This site provides information about the Federal basis mandating TMDL development. It also provides reports to the state legislature concerning TMDL development.