Research Technical Report

Water Quality Monitoring in Elkhorn Slough: A Summary of Results 1988-1996

Caffrey, J., S. Shaw, M. Silberstein, A. DeVogelaere, and M. White (1997)

Elkhorn Slough Technical Report Series 1997:1

ABSTRACT

Elkhorn Slough National Estuarine Research Reserve (ESNERR) and the Elkhorn Slough Foundation (ESF) in cooperation with Monterey County Water Resources Agency have been supporting a volunteer water monitoring program since 1988. Twenty four stations are sampled monthly for temperature , salinity, dissolved oxygen, pH, turbidity, nitrate ammonium, and dissolved inorganic phosphate. This program represents a partnership among ESNERR, ESF, Monterey County Water Resources Agency, National Oceanic and Atmospheric Administration, California Department of Fish and Game, and highly dedicated volunteers. Some trend we have observed from this data include:

• a significant increase in nitrate concentrations since the 1970's
• extraordinarily high nitrate concentrations in the lower Salinas River which may be the highest recorded in scientific literature for a river or estuary
• concentrations of ammonium that are an order of magnitude lower (or more) than nitrate
• low concentrations of dissolved oxygen in some areas which have restricted circulation
• opening of the Salinas River lagoon leads to rapid increases in salinity in the lower river even during the rainy season when river discharge is high