Delta Water Quality Program

Delta Water Quality

Table of Contents

Why is water quality in the Delta important?

The Sacramento-San Joaquin Delta is the freshwater portion of the Bay-Delta Estuary, the largest estuary on the west coast. Originally marshland, the Delta is a network of channels, land protected by levees and few tidal wetlands. Receiving runoff from over 40 percent of the State, the Delta supplies water for millions of acres of agricultural lands, homes and businesses. The Delta is essential habitat for many species of fish, birds, mammals and plants.  The Delta and its watershed are relied upon by California Native American tribes and local communities for cultural purposes, drinking water, subsistence fishing, and recreation.

The Delta is considerably altered by land conversion, water management and diversions, climate change, invasive species and contaminants. These alterations are associated with significant declines in native species that depend on Delta ecosystems. Ongoing efforts to restore habitats and balance the wide range of water uses are occurring with an expectation that the Delta will continue to be challenged and change.

The Central Valley Water Board shares responsibility with the State Water Resources Control Board of protecting beneficial uses of water in the Delta.

Delta Regional Monitoring Program

The Delta Regional Monitoring Program is a Regional Water Board-initiated stakeholder effort to address the need for a comprehensive monitoring, assessment and reporting program for water quality in the Delta. This Program completes monitoring and reporting in accordance with Resolution R5-2021-0054. Additional information may be found at the Water Board’s Delta Regional Monitoring Program webpage.

Delta Nutrient Research Plan

The Delta Nutrient Research Plan identifies gaps in our understanding of nutrients and potential impacts of management measures in the Delta. Staff are implementing the Delta Nutrient Research Plan through special studies and in coordination with the Delta Regional Monitoring Program’s focus on nutrients. Additional information may be found at the Water Board’s Delta Nutrient Research Plan webpage.

Delta Methylmercury Control Program

The Delta Methylmercury TMDL and associated program of implementation, collectively referred to as the Delta Mercury Control Program (DMCP) was adopted as a phased TMDL by the Regional Board in 2010. The first phase of implementation required entities responsible for discharging methylmercury in the Delta to conduct source control studies and evaluate and develop methylmercury management methods. The Water Board is currently reviewing the DMCP. Additional information may be found at the Water Board’s Delta Methylmercury TMDL webpage.

Low Dissolved Oxygen in the Stockton Ship Channel

To reverse periodic conditions of low dissolved oxygen and maintain suitable habitat for migrating fish, the Port of Stockton operates an aeration facility in the Stockton Deepwater Ship Channel. The aerator was installed as a TMDL implementation action. Additional information may be found at the Water Board’s San Joaquin River Dissolved Oxygen TMDL webpage.

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