Freshwater quality monitoring in the San Francisco Bay Area: 2013-2014 biennial report

Wallitner, Katie

The National Park Service (NPS) San Francisco Bay Area Network (SFAN) Inventory and Monitoring Program monitors freshwater streams in John Muir National Historic Site (JOMU), the Presidio of San Francisco (PRSF), Muir Woods National Monument (MUWO), Pinnacles National Park (PINN), Point Reyes National Seashore (PORE), and Golden Gate National Recreation Area (GOGA). SFAN vital signs, or indicators of ecosystem health, represent a suite of ecological phenomena operating at a range of temporal and spatial scales. SFAN managers and specialists ranked freshwater quality as one of the most important vital signs (Adams et al. 2006). SFAN units support highly-valued aquatic resources that are significant in an ecological and economic context, including many federally protected species. Water years (WYs) run from October 1st to September 30th of each year. This report summarizes water quality data from 25 SFAN sites monitored during WYs 2013 and 2014 (10/1/2012 – 9/30/2014), including 11 sites in the Redwood Creek watershed (GOGA/MUWO), nine sites in the Lagunitas Creek watershed (PORE/GOGA), and five sites in the San Francisquito Creek watershed (GOGA). During WYs 2013-2014, NPS staff made a total of 550 site visits; visits occurred monthly and additionally during storm events. During these visits staff collected data for select water quality parameters, employing the methods set forth in the peer-reviewed SFAN Freshwater Quality Monitoring Protocol (Cooprider and Carson 2006). Core parameters measured in the field included temperature (air and water), dissolved oxygen, pH, specific conductance, and turbidity. Samples collected in the field were tested for pathogenic indicator bacteria (Escherichia coli [E. coli] and total coliform) and nutrient parameters (nitrate as nitrogen and total Kjeldahl nitrogen [TKN]). Staff conducted fecal coliform sampling at the Olema Creek watershed sites as well, following a schedule set by the San Francisco Bay Regional Water Quality Control Board’s (RWQCB) Tomales Bay Pathogen Total Maximum Daily Load (TMDL) program. Only half of the SFAN freshwater quality parameters have established objectives put in place by the RWQCBs or the United States Environmental Protection Agency (EPA); other parameters (temperature, specific conductance, turbidity, and nitrate) do not have established water quality objectives, and are compared to ecological objectives drawn from scientific literature. In this report, the percentage of results that fail to meet any type of objective will be referred to as the failure rate. When grouping SFAN water quality results from all WY 2013-2014 site visits, the pH, specific conductance, turbidity, and fecal coliform results most frequently met the objectives: only two percent of pH results failed to fall within the objective range; six percent of specific conductance results exceeded the ecological objective maximum of 500 µS/cm; seven percent of turbidity results exceeded the ecological objective maximum; and only seven percent of fecal coliform results exceeded the contact recreation maximum of 400 MPN/100mL. Overall, the nitrate (as nitrogen) and the dissolved oxygen datasets had the highest failure rates (21 and 20 %, respectively). However, due to the variability between watersheds, much higher failure rates were revealed when grouping results by watershed. The Lagunitas Creek watershed exhibited the highest failure rate for nitrate (31% exceeded the ecological objective maximum of 0.30 mg/L) while the San Francisquito Creek watershed exhibited the highest failure rate for dissolved oxygen (39% fell below the dissolved oxygen minimum objective of 7 mg/L). Of the three watersheds, the Redwood Creek sites most frequently met the water quality objectives.

Freshwater quality monitoring in the San Francisco Bay Area: 2013-2014 biennial report

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