TMDL for Nutrients in Lower Salinas River Watershed, Monterey County, California

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A watershed-related issue examined by the ENVS 560/L Watershed Systems class at CSUMB.

Surface nitrate concentrations and estimated source contributions in the LSRW.

Summary

Excess nitrates in surface water are the cause of many nutrient and biostimulatory-related (chlorophyll, turbidity, etc) impairment listings as part of the section 303 (d) of the Clean Water Act in the LSRW.

Location

Resource/s at stake

Drinking water is an important resource which has been threatened by high levels of nitrates in the Lower Salinas River Watershed [1][2][3].

Stakeholders

Laws, policies, & regulations

Regulatory background

...What laws, policies, and/or regulations are involved?...

Preliminary draft project report for nutrient TMDLs (Lower Salinas River Watershed)

Surface nitrate concentrations and estimated source contributions in the LSRW.

A recent (March 2012) preliminary draft project report by the California Regional Water Quality Control Board, (CRWQCB) Central Coast Region (CCRWQCB) on TMDLs for nutrients in the Lower Salinas River Watershed[4].

In this document, the work group identifies multiple beneficial uses (BUs) as impaired, including those for drinking water supply, livestock watering, and aquatic habitat BUs.

From the preliminary draft document[4]:

"Problem Statement: "Discharges of nitrogen compounds and orthophosphate are occurring at levels in surface waters which are impairing a wide spectrum of beneficial uses and, therefore, constitute a serious water quality problem. The municipal and domestic drinking water supply (MUN, GWR) beneficial uses and the range of aquatic habitat beneficial uses are currently impaired; potential or future beneficial uses of the agricultural irrigation water supply (AGR) for sensitive crops may be impaired..."

"A total of 34 waterbody/pollutant combinations are impaired due to exceedances of water quality objectives. The pollutants addressed in this TMDL are nitrate, un-ionized ammonia, and orthophosphate – orthophosphate is included as a pollutant due to biostimulatory impairments of surface waters. Reducing these pollutants is also anticipated to address several 303(d)-listed dissolved oxygen and chlorophyll a impairments in the TMDL project area."

Systems

... What elements of the biophysical system are/were involved?...

Science

Studies to determine nitrate concentrations in groundwater have been conducted in the LSRW.

Tools

...What analytical (e.g. modeling) tools were or could be used?...

Future research

...What knowledge gaps remain?...

...Suggest a CWSP MS thesis topic that could contribute to the issue...

...Suggest a topic for a hypothetical study that had unlimited resources...


References

  1. UC Davis study on elevated nitrates as a threat to drinking water and public health in the Salinas Valley [1]
  2. 2012 UC Davis study on groundwater nitrate contamination in California [2]
  3. Article on agricultural impacts on groundwater nitrate [www.swhydro.arizona.edu/archive/V8_N4/feature2.pdf]
  4. 4.0 4.1 Link to Waterboard TMDLs for Nutrients in the Lower Salinas Watershed [3]

See also

Disclaimer

This page may contain student work completed as part of assigned coursework. It may not be accurate. It does not necessary reflect the opinion or policy of CSUMB, its staff, or students.