Elkhorn Slough
Water Quality Report Card

View annual scores for individual sites.
View annual scores for each region
calculated from all sites within that region.
View annual scores for the whole estuary
calculated from all sites.







Sampling Site

Click on parameter for definition
Click on a sample site then a parameter to see a chart of yearly results.
About the Water Quality Monitoring Program

Water quality monitoring at Elkhorn Slough started in 1988 through the Volunteer Program developed originally by researchers at Moss Landing Marine Laboratories and was subsequently coordinated by the Elkhorn Slough National Estuarine Research Reserve (ESNERR) with support from the Elkhorn Slough Foundation (ESF) and the Monterey County Water Resources Agency. Under this program, 24 stations located throughout the Slough are sampled monthly for:

  1. temperature
  2. salinity
  3. conductivity
  4. dissolved oxygen
  5. pH
  6. turbidity
  7. nitrate
  8. orthophosphate
  9. ammonium
  10. free ammonium
  11. chlorophyll a
  12. algal cover

How water quality scores are calculated

Nine different water quality attributes that are considered essential for ecological health were compared to thresholds of concern identified by the regional water quality control board. These attributes include oxygen levels, essential for animal health, and nutrients, which, in excess, can overstimulate growth of algae. Neither pesticides nor bacteria are sampled. The final grade assigned to each site integrates how the concentrations of each of the nine water quality attributes compare in frequency and magnitude to their relative threshold. Should you have any questions or suggestions please don't hesitate to email John Haskins, water quality specialist, at john@elkhornslough.org.

Rainfall data

Rainfall data are from the National Center for Environmental Information. For water years prior to 2008 rainfall amounts are for Watsonville. After 2008 rainfall amounts are for Castroville.

What you can do:

  • Limit the use of fertilizers in your garden.
  • Maintain septic systems to avoid leakages.
  • Dispose of pharmaceuticals properly, and prevent harsh soaps and other contaminants from running into storm drains.
  • Buy produce from local farmers applying sustainable management practices.
  • Vote for the environment by supporting candidates and bills favoring clean water and habitat restoration.
  • Let your elected representatives and district officials know you care about water quality in Elkhorn Slough and support efforts to reduce polluted run-off and to restore wetlands.
  • Attend meetings of the Central Coast Regional Water Quality Control Board to share your concerns and support for action.
  • Volunteers have been instrumental in collecting these data over the decades and we are always looking for dedicated volunteers to help. If you would like to assist us, please contact John Haskins: john at elkhornslough.org.
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