Old and Middle River Pump Stations Water Quality Monitoring Instrumentation Improvements Project

This Project consists of the installation of upgraded water quality monitoring equipment at CCWD’s Old River and Middle River intakes in the Sacramento-San Joquin Delta. Currently, water samples at these intakes are pumped out of wet wells that pass through two-inch diameter piping, which is at high risk of being blocked by the spread of invasive golden mussels (Limnoperna fortunei). The purpose of this project is to install new water quality monitoring equipment that will provide more reliable monitoring data and will decrease the risk of being blocked by golden mussels. A total of two multiparameter sondes will be installed, one at Old River and one at Middle River. Each sonde will be incased in a six-inch diameter HDPE pipe stilling well and mounted to the existing concrete cantilever platforms located in front of the fish screen at each intake, where they will extend into the water to collect water quality data. These larger diameter stilling wells will significantly decrease the risk of clogging due to golden mussels and will be easier to access and maintain. See Figure 1 for a Project vicinity map and Figures 2 and 3 for Project location maps. Data from these sondes will be transmitted back to the electrical building at each site through new and existing conduits. The Project is expected to take three months, with construction occurring between June and August of 2026. Equipment laydown and vehicle staging will occur in previously disturbed areas, such as paved roads and parking areas, within the boundaries of the pump stations on CCWD property. The following types of equipment are expected to be present at the project site: crew trucks, a boat or barge, and power tools. Project activities will occur in previously developed and disturbed areas on CCWD property. No vegetation removal or tree removal will occur. No ground disturbance will occur, and there will be no impact to the banks or beds of the rivers at either intake. Equipment installation will occur from land via the concrete cantilever platforms and from a boat or barge in the water immediately below the platform. The Project is not anticipated to adversely affect natural resources or areas of known cultural or historic resources.