Improved Monitoring of Water Quality and Pelagic Organism Decline in the Delta with Continuous In Situ Sensor Measurements

Science Center Objects

Newly-developed, commercially-available sensors permit real-time collection of water quality data that may help identify ecosystem processes that affect the health of pelagic food webs in the Sacramento – San Joaquin Delta. In particular, the simultaneous measurement of nutrients, organic matter and algal abundance along with the basic water quality variables such as temperature and salinity - will provide clearer evidence for linkages between physical and chemical drivers and ecosystem dynamics over short time scales, as well as show how short-term events are expressed in long term trends.

Instruments on back of boat being ready to be deployed in open water.

Example instrument package for deployment at Liberty Island.

(Public domain.)

We will continuously monitor the variability of several key water quality parameters in situ at Liberty Island to 1) identify physical and hydrologic processes affecting pelagic habitat and food webs; 2) assess the importance of episodic events (type, magnitude and duration) on habitat quality and food resources, and 3) provide this data in real-time to the IEP research community for incorporation into models and comparison with other measurements (e.g. fish, zooplankton, etc.). Data of this type will allow the research and management community to link water supply, water quality, nutrient sources, and algal production to the pelagic food web in new ways. We view such data as an important component of the long term monitoring program for the Delta, and as critical for evaluating long-term trends, assessing environmental health, and evaluating the effectiveness of habitat restoration and contaminant mitigation programs.

We will deploy a sensor platform designed to simultaneously collect continuous (e.g. 15 minute) real-time chemical and physical measurements inter-calibrated with discrete laboratory measurements. Our design is for this platform to also serve as a testbed that can accommodate new water quality or climate sensors provided by collaborators or vendors. We propose to make continuous measurements of CDOM fluorescence, nitrate, chlorophyll-a fluorescence, turbidity, dissolved oxygen and several key ancillary parameters (specific conductance, pH, water temperature). The proposed budget allows for the addition of a wet chemical sensor for phosphate. A small buoyed platform will house the sensors along with system power and solar recharging system, master dataloggers, a telemetry system, an autosampler, and associated electrical cables. Sensors will be mounted below the platform in a submersible stainless steel cage and deployed mid-way in the water column. The goal will be to collect data through at least the end of the fiscal year to enable the collection of data across a range of hydrological and climatic conditions, and we will leverage several existing USGS studies on Liberty Island.