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Delta Watch

The Great Delta Toilet Bowl

Info on sewage discharges

Major Wastewater Discharges

Municipalities in and upstream of the Delta increasingly use the estuary as a TOILET BOWL for their sewage discharges. With each flush comes increased pollution, including toxic contaminants such as ammonia, heavy metals, and even pharmaceuticals. As population continues to increase in the region, so will wastewater discharges and their impacts on the estuary. Consider the following:

  • The Sacramento region is by far the largest polluter and each day discharges over 146 million gallons of partially treated sewage into the Delta. Contained in this wastewater are significant concentrations of ammonia. On a monthly basis, Sacramento adds 125,000 gallons of ammonia to the Delta - far more than any other source. These discharges are believed to have a significant impact on the delta smelt and other threatened and endangered species.
  • In addition to Sacramento, another dozen municipalities each day flush an additional 200 million gallons of treated sewage directly into the heart of the Delta. These discharges have grown substantially over the past 30 years as populations have expanded.
  • The Stockton wastewater treatment plant has been repeatedly cited for illegal discharges of toxic contaminants. A recent lawsuit identifies over 1,500 sewage spills in Stockton over the past 5 years, endangering human health and the environment.
  • Another 600 million gallons of treated sewage is discharged each day by some 300 additional communities upstream of the Delta.
  • A 2008 investigation by the Associated Press revealed the presence of pharmaceuticals in the drinking water of major metropolitan areas. Scientific evidence suggests even small amounts of such substances - including estrogen, antibiotics and heart medications - may adversely affect habitat and fish species. A 2014 study detected concentrations of pharmaceuticals, including carbamazepine,fluoxetine, and trimethoprim, within the vicinity of the Sacramento Wastewater Treatment Plant in concentrations that could be chronic to aquatic organisms within the Delta.
  • Despite the availability of more stringent treatment methods, Sacramento and other wastewater treatment facilities have not yet implemented these technologies.

Sources: Sacramento Bee, Associated Press

*Information related to the Major NPDES dischargers in the Sacramento/San Joaquin Delta Watershed was retrieved from the California Integrated Water Quality System Project (CIWQS) Regulated Facilities Report available on the website of the State Water Resources Control Board as well as the respective NPDES permits issued to each facility.

Additional Information

Probe: Pharmaceuticals In Drinking Water

The Great Delta Toilet Bowl

New Research Links Delta Decline to Ammonia from Wastewater Discharges
Press Release | Full Study

Ammonia Toxicity Study (UC Davis)
Full Study

Congressmen Costa and Cardoza request immediate action on ammonia discharges
Copy of Letter

Feinstein letter calls on Regulators to address sewage problem
Copy of Letter

Latest News:

Central Valley Water Board fines Stockton $63,000 for several wastewater violations
Article from the Lodi News Sentinel
(May 11, 2011)

Discovery Bay fined again for wastewater discharges
Article from the San Jose Mercury News (May 10, 2011)

Sewage spills draw lawsuit
A conservation group has followed through on its threat to sue the City of Stockton for 1,530 sewer overflows and other violations. The illegal discharges are believed to be a significant cause of declines in the delta environment and impacts to fish. Article in Stockton Record (Sept. 24, 2008)

Ammonia from Sacramento Linked to Delta Decline
Sacramento’s regional sewage treatment plant is the largest single source of ammonia in the Delta. It releases about 146 million gallons of treated wastewater each day directly into the Sacramento River. The ammonia load in the wastewater has more than doubled since 1985 due to rapid urbanization, and is now more than 125,000 gallons per month. Two recent studies show that ammonia disrupts the food chain in the Sacramento-San Joaquin Delta. Editorial in Stockton Record (June 11, 2008)