Elkhorn Slough National Estuarine Research Reserve (ESNERR), the Elkhorn Slough Foundation (ESF), and the Monterey County Water Resources Agency have been supporting a volunteer water monitoring program since 1988. Twenty-six stations (see map) are sampled monthly for temperature, salinity, dissolved oxygen, pH, turbidity, nitrate, ammonium, and dissolved inorganic phosphate. The data are collected in the field by a singularly dedicated and reliable volunteer, Sue Shaw, with assistance from other volunteers.
In 1997, Jane Caffrey (the ESNERR research coordinator at that time) and collaborators analyzed the water quality data collected from 1988-1996. They also referenced water quality data collected in the 1970s in the same region. Click here to download their complete summary report (310KB / PDF).
Some trends observed from this data include:
- A significant increase in nitrate concentrations since the 1970s
- 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.
More recently, the Elkhorn Slough was awarded two different non-point source pollution monitoring grants to examine the water quality data in more detail. Starting in late 2005, a Quality Assurance Project Plan (QAPP) was developed for the acquisition and maintenance of all water quality data, made available to the Central Coast Regional Water Quality Control Board (CCRWQCB).
Under the first of these two grants, the 18-year record of water quality data were analyzed for statistically observable changes in nutrient concentrations in the time periods before and after some concerted restoration efforts were completed in the Slough watershed by the Elkhorn Slough Foundation. ESNERR Environmental Chemist Alison Gee has written a manuscript summarizing those results, which will be posted in published form in 2009. Download a mini-presentation of a subset of those results: minipresentation.pdf (4.4MB)
Also under this first grant, CSUMB environmental scientist Marc Los Huertos working in conjunction with several UCSC statisticians have produced detailed statistical analyses of the long-term trends in several water quality parameters measured in the Elkhorn Slough. These include temperature, dissolved oxygen, pH, salinity and dissolved inorganic nutrients. Download a summary report of these analyses: ESNERR_WQ _Statistical_Analyses.pdf (1.5MB)
On the second grant, a baseline investigation of eutrophication symptoms throughout the 24 volunteer water quality monitoring stations is being undertaken. Parameters to be focused on for this study include night-time dissolved oxygen, chlorophyll and nutrient concentrations, macro-algal coverage estimates and light penetration depths. For further information on either of these projects, please contact John Haskins.
To request a copy of some or all of our volunteer monitoring data, download and print the request form (PDF) and email it to us. Please describe the project for which you need the data and sign the waivers both acknowledging that the data may contain errors and agreeing to request our permission before further dissemination of the data. Upon completion of these forms, we will email you the data in an Excel spreadsheet.