The California Water Boards' Annual Performance Report - Fiscal Year 2008-09

PLAN AND ASSESS: TOTAL MAXIMUM DAILY LOAD

MEASUREMENTS

WHAT THE MEASURE IS SHOWING

In Fiscal Year (FY) 2008-09, the regional boards adopted 12 TMDL projects that addressed 55 waterbody-pollutant combinations, or listings, to help restore impaired water bodies in the State.  Another nine TMDL projects, which address 25 more listings, were underway.  Since the early 1990s, the regional boards have adopted numerous TMDL projects, addressing nearly 750 listings, or 33 percent of the 2,238 listings on the Water Boards’ latest impaired waters list (adopted in 2006).  Two percent of those listings were addressed in FY 2008-09.  It is clear from the regional breakdown of listings addressed that most impaired water bodies and TMDL activities occur in the regions with relatively higher population densities.

WHY THIS MEASURE IS IMPORTANT

When it is determined that a waterbody is too polluted to meet its water quality standards, the waterbody is considered degraded and put on the Water Boards’ list of impaired waters.  A total maximum daily load (TMDL) is required for impaired waters to restore them to conditions that support their beneficial uses.  The TMDL specifies the pollutant loading that a waterbody can receive and still meet standards, and allocates the pollutant loading that may be attributed to each source of the pollutant.  TMDLs, along with their implementation plans, are adopted by the regional boards and the state board.  US EPA approves each TMDL project.  This lengthy process involves dischargers and many other stakeholders.  Subsequently, those responsible for the pollutant sources that cause or contribute to the impairments take corrective actions to protect the water bodies.

TECHNICAL CONSIDERATIONS

• Data Source:  TMDL Planner/Tracker database.  Period: July 1, 2008 to June 30, 2009.  Extracted on July 31, 2009.
• Unit of Measure:  Number of TMDL projects adopted and TMDL listings addressed in FY 2008-09.
• Data Definitions:  TMDL project:  A TMDL project is a planned strategy to reduce pollution in an impaired water body so that its water quality standards are met.  A TMDL project addresses one or more pollutants for a given waterbody or segment of waterbody (known as TMDL listings).  TMDL listing:  A TMDL listing refers to a pairing of a waterbody and a pollutant that is responsible for the impairment (i.e., each water body-pollutant combination is called a listing).  A given waterbody is impaired due to the presence of one or more pollutants (each called a listing) and a TMDL project may address more than one listing.  The current TMDL projects and listings are documented in the Water Boards’ 2006 Clean Water Act Section 303(d) list (https://www.waterboards.ca.gov/water_issues/programs/tmdl/docs/303dlists2006/epa/state_usepa_combined.pdf).
• References:  More information on the Water Boards’ TMDL activities is available at:  https://www.waterboards.ca.gov/water_issues/programs/tmdl/

GLOSSARY

Impaired Water

An impaired waterbody is one that does not meet the water quality objectives established to protect the beneficial uses of the water due to the presence of one or more pollutants.  Such waters are identified on the Water Boards’ Clean Water Act Section 303(d) list.

Pollutant

A pollutant is a waste or substance that, at certain levels, can cause waterbody impairment.  The monitoring programs of the Water Boards and others provide information on the levels of pollutants in the State’s waters.

(Updated 9/20/11)