Aqueducts are known to constrain some ground-based wildlife species’ movement patterns and may prohibit gene flow for certain suites of species that either are averse to traversing available crossing facilities or where crossing structures are spread too widely. In 2020 the California Department of Water Resources launched an ambitious effort to prepare two Habitat Conservation Plans (HCPs) to cover Operations and Maintenance (O&M) Activities for the State Water Project (SWP), which relies upon the use of aqueducts to supply water from Northern California to Southern California. The SWP delivers water to 27 million Californians, 750,000 acres of farmland, and businesses throughout the state. Historically, critical O&M activities have been delayed or avoided due to the challenges of project-by-project approvals needed from the wildlife agencies and aquatic resource permitting agencies. The Delta-HCP covers SWP properties and infrastructure in nine counties covering a total of approximately 10,000 acres, and the San Joaquin-HCP touches three counties and covers approximately 14,000 acres. In support of these HCPs, DWR partnered with Dudek to conduct a range of vegetation mapping, aquatic resource evaluations, habitat assessments, surveys for several listed and sensitive species, bat acoustic studies, and wildlife movement studies within each plan area.
Portions of the study area support endangered and threatened species like the San Joaquin kit fox, Tipton’s kangaroo rat, giant kangaroo rat, and others. In fact, the SWP aqueduct is thought to form the de facto boundary between the listed Tipton’s kangaroo rat and a closely related subspecies. In order to identify the suite of affected species and extent of potential constraints, and to evaluate potential hot spots and opportunities, a wildlife movement study was performed using primarily camera traps. Wildlife movement studies across this 200+ mile linear water “transportation” corridor covered nearly 400 crossing structures and locations, captured over 2 million photos, leveraged Artificial Intelligence (AI) tools to identify more than 200,000 wildlife photos which were then reviewed by researchers. The data are being combined with separate San Joaquin kit fox camera study data, listed kangaroo rat trapping study data, and road mortality data from proximate highways to provide a robust combined dataset to support evidence-based analyses. Results to date indicate that at least 14 mammalian and 6 reptile/amphibian species are using crossing structures to cross the aqueduct, and in 2 instances, animals were observed swimming across the waterway. One state species of concern (American badger) and the federally endangered and state threatened San Joaquin kit fox were observed using some crossings. The results of the study will be used to assist in avoidance and minimization mitigation decisions and identify locations where wildlife movement corridor improvements could be made to support and enhance wildlife movement and genetic flow across the aqueduct system.