California Department of Fish and Wildlife

Dissolved Oxygen

Problem Statement

photo of rainbow trout

Photo by Rick Weaver

Oxygen depletion occurs at isolated locations in the Delta, causing dissolved oxygen concentrations to fall below the water quality criteria. In most locations in the Delta the water quality criteria is 5 milligrams/liter. In the San Joaquin River between Turner Cut and Stockton from 1 September through 30 November the water quality objective is 6 milligrams/liter. Oxygen depleting substances are found in various discharges. The substances may either exert a direct oxygen-depleting effect (i.e., biochemical oxygen demand) or decrease oxygen by an indirect method (i.e., nutrients that cause algal growth, which eventually die off and exert an oxygen demand). Low dissolved oxygen impairs or blocks fish migration, kills aquatic organisms (including fish), creates odors, and impairs fish reproduction and juvenile rearing.

ERP has supported projects that:

  • Developed a detailed conceptual model for dissolved oxygen in the Stockton Deep Water Ship Channel.
  • Conducted a comprehensive monitoring of sources and fate of oxygen-consuming materials in the San Joaquin River watershed between Channel Point and Lander Avenue.
  • Developed a technically defensible modeling framework for the Stockton Deep Water Ship Channel that represents the dissolved oxygen dynamics in the system.
  • Provided independent scientific review of models created to evaluate dissolved oxygen concentrations in the Stockton Deep Water Ship Channel.
  • Modeled hydrodynamic and biogeochemical processes of the San Joaquin River within the Deep Water Ship Channel.
  • Conducted scientific studies to develop a low dissolved oxygen management strategy for the Stockton Deep Water Ship Channel.
  • Evaluated past data to determine sources of nutrient loads in the San Joaquin River.
  • Synthesized projects prior to 2001 and formulated an initial approach for allocation of responsibility for control of oxygen-demanding substances that enter the Stockton Deep Water Ship Channel and cause dissolved oxygen depletion below the water quality objective

Current projects include:

  • A monitoring study that collects estuary data to be used in a comprehensive upper watershed/estuary watershed model to assist the Central Valley Regional Water Quality Control Board understanding loads of oxygen demanding substances.

Dissolved Oxygen Related Links

Central Valley Regional Water Quality Control Board

Department of Water Resources

San Joaquin River Dissolved Oxygen Technical Working Group

For more information, contact Carol Atkins at or (916) 445-0074.