Elkhorn Slough and Bennett Slough Biostimulatory Substances TMDL


Problem Statement - This TMDL project will address surface water quality impairments in the Elkhorn Slough watershed which are caused by exceedances of water quality criteria for dissolved oxygen, pH, un-ionized ammonia, chlorophyll-a, and associated nutrient-related problems such as excessive nitrate, orthophosphate, and excess algal biomass.  These impairments are presumed to impact a range of current or potential designated beneficial uses of surface waters - including aquatic habitat, recreation, and fishing. This project will identify the water quality impairments and develop a plan for the attainment of water quality objectives and the restoration of designated beneficial uses of surface waters.


Monitoring Data Sets

Staff compiled monitoring data from five monitoring programs covering the period 1989 to 2015. A summary of the data files available to download is here:

File Name
(R dataframe or CSV)
No. Rows No. Columns Description
elkhorn.csv (zip file)
9,191,583 17 Elkhorn Slough monitoring data from 1989 - 2015. 19 analytes. 55 Stations.
elkwide.csv (zip file)
1,402,169 48 Reshaped data - each analyte in a separate column.
55 15 Site information for 55 monitoring stations, includes lat., lon., dist. from mouth.
18 13 Summary statistics - by analyte. Includes sample size, mean, interquartile range, min, max, median, percentiles.
650 13 Summary statistics - by analyte, by station.
7,722 14 Summary statistics - by analyte, by station, by year.
71,199 17 Summary statistics - by analyte, by station, by year, by month.

For Additional Information

For more information, visit www.elkhornslough.org. This website includes information from the Elkhorn Slough National Estuarine Research Reserve, Elkhorn Slough Foundation, California Fish and Wildlife, and the National Oceanic & Atmospheric Administration.

  Subscribe to our Email Lists


Status and Public Notices

  • Status: In development.
  • Public Notice: None at this time.

Approval status

  • None at this time.