Overview

What is a TMDL?

A Total Maximum Daily Load (TMDL) is a calculation of the maximum amount of a pollutant that a water body can receive and still meet water quality standards, and an allocation of that amount to the pollutant's sources.

Water quality standards are set by States, Territories, and Tribes. They identify the uses for each water body, for example, drinking water supply, contact recreation (swimming), and aquatic life support (fishing), and the scientific criteria to support that use.

A TMDL is the sum of the allowable loads of a single pollutant from all contributing point and nonpoint sources. The calculation must include a margin of safety to ensure that the water body can be used for the purposes the State has designated. The calculation must also account for seasonal variation in water quality.

The Clean Water Act, section 303, establishes the water quality standards and TMDL programs.  Water bodies are identified as being impaired if they do not meet these standards.

Click here to access the U.S. Environmental Protection Agency's TMDL web site to see the impaired water bodies in the State of California. Other California TMDL information can be found at the California State Water Resources Control Board (SWRCB) TMDL site.

SAWPA and TMDLs

The Santa Ana Regional Water Quality Control Board (RWQCB) is responsible for developing and implementing TMDLs in the Santa Ana River watershed. This state agency has requested SAWPA's assistance in this process for two areas, the Chino Basin area and the San Jacinto (Lake Elsinore and Canyon Lake) area.

• TMDL Newsletter (October 2002)

Chino Basin TMDL

The RWQCB has requested SAWPA’s assistance in serving as a neutral facilitator for the TMDL development process for Chino Creek, the Santa Ana River Reach 3, and Prado Park Lake.  Activities include administering all monitoring and review meetings, taking minutes, conducting meetings, building consensus, and encouraging involvement of all interested stakeholders in the TMDL development process. Full staffing costs are covered by the RWQCB and no SAWPA member district contributions are required. The following are goals of the facilitation process:

• Provide facilitation support for the TDML Process. This is an ongoing activity that will continue through the sampling and data analysis period in 2003.

• Seek grant funds from Prop 13 for modeling support. On October 16, 2002, the State Water Resources Control Board approved funding to support this modeling activity under the Proposition 13 Non Point Source (NPS) program.

Click on the following link for a fact sheet on the Chino Basin TMDL program.

Meetings for the Chino Basin TMDL are held at SAWPA approximately every month as needed.  Meeting notices are posted at SAWPA; contact SAWPA if you would like further information.

San Jacinto TMDL

The RWQCB has also requested SAWPA’s assistance in serving as a neutral facilitator for the TMDL development process for Lake Elsinore and Canyon Lake. These activities include administering all monitoring and review meetings, taking minutes, conducting meetings, building consensus, and encouraging involvement of all interested stakeholders in the TMDL development process. Full staffing costs are covered by the RWQCB. In addition, a grant will be awarded to SAWPA to commence water quality modeling of the nutrient sources contributing to the downstream lakes. The grant will be combined with LESJWA contributions. Administrative costs by SAWPA to conduct this study will be covered by grant funds. Ongoing activities include:

• Provide facilitation support for the TMDL process

• Develop a nutrient source model to assist in the development of TMDLs.

Click on the following link for a fact sheet on the San Jacinto Basin TMDL program.

Meetings for the San Jacinto TMDL are held at SAWPA approximately every month as needed.  Meeting notices are posted at SAWPA; contact SAWPA if you would like further information.

Copyright: Santa Ana Watershed Project Authority, 2002
Last modified 07/23/2004