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.
- Map of the project area
- Maps of Median Water Quality Concentrations:
- dissolved oxygen
- dissolved oxygen (saturation)
- un-ionized ammonia (NH3) as nitrogen
- total ammonia as nitrogen
- ionized ammonia (NH4) as nitrogen
- nitrate as nitrogen
- nitrate + nitrite as nitrogen
- nitrite as nitrogen
- total nitrogen
- orthophosphate as P
- total phosphorus
- floating algae
- specific conductivity
- July 9, 2019 - Agenda for the pre-kickoff meeting for the Elkhorn Slough nutrient modeling contract. Please visit the Elkhorn Slough's Coastal Training Program's website for presentation materials.
- September 28, 2018 - Technical Support for Elkhorn Slough Nutrient Total Maximum Daily Load (TMDL) Development, prepared by Tetra Tech and the Elkhorn Slough Foundation
- November 29, 2016 - PowerPoint presentation from public meeting.
- September 27, 2016 - Draft Analysis Report
- February 19, 2015 - TMDL kick-off meeting PowerPoint presentation and agenda.
- February 6, 2015 - Fact sheet
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:
(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
- To be notified of updates and meetings regarding this TMDL please subscribe to the Elkhorn Slough and Bennett Slough biostim TMDL email subscription list
- Shanta Keeling
Status and Public Notices
- Status: In development.
- Public Notice: Agenda for Dec. 15 and 16, 2021 stakeholder meeting.
- None at this time.