Total Maximum Daily Loads

What is a TMDL?

The Total Maximum Daily Load (TMDL) process leads to a "pollution budget" designed to restore the health of a polluted or impaired body of water. The TMDL process provides a quantitative assessment of water quality problems, contributing sources of pollution, and the pollutant load reductions or control actions needed to restore and protect the beneficial uses of an individual waterbody impaired from loading of a particular pollutant. More specifically, a TMDL is defined as the sum of the individual waste load allocations for point sources, load allocations for non-point sources, and natural background such that the capacity of the water body to assimilate pollutant loading (the loading capacity) is not exceeded (40 CFR §130.2).

In other words, a TMDL is a calculation of the maximum amount of a pollutant that a waterbody can receive and still meet water quality standards. This calculation also includes a margin of safety and consideration of seasonal variations. In addition, the TMDL contains the reductions needed to meet water quality standards and allocates those reductions among the pollutant sources in the watershed. See the Introduction to TMDLs fact sheet for more information.

Guidance Document for the Control of Excess Sediment Discharges

The Guidance Document is intended to provide examples of excess sediment discharge sites, sediment control practices, road management practices, and sediment assessment methods.  It will also contain suggested content for a comprehensive inventory, prioritization, and sediment control plan.  Monitoring guidance may also be included.

The Guidance Document is under development, although it is currently a low priority for staff completion.  It will be presented to the Board upon completion.

For information, comments, and questions on the Guidance Document, please contact Lisa Bernard at 576-2677 or

Sediment TMDL Implementation Monitoring Strategy

The Monitoring Strategy is intended to provide feedback on the recovery of sediment-impaired water bodies and the success of the Sediment TMDL Implementation Strategy and efforts to reduce excess sediment discharges.  It will include monitoring objectives, the locations of trend monitoring stations, a description of the parameters to be monitored, benchmark conditions, measurable milestones, and specific due dates for monitoring and data analysis.

The Monitoring Strategy is under development.  It will be presented to the Board upon completion, which is expected in 2017.

For information, comments, and questions on the Monitoring Strategy, please contact Lisa Bernard at 576-2677 or

The Integrated Report - 303d List and 305b Report

California has integrated the 303(d) List of Impaired Waters and the 305(b) Water Quality Assessment Report into a single report (Integrated Report). This Integrated Report satisfies the requirements of both CWA Sections 303(d) and 305(b).
To visit the Integrated Report webpage, please click on the link below.

  (Page last updated 9/2/21)