Monitoring for Impact of Groundwater Management Plans on Critical Riparian Habitat
Chino Basin Watermaster and Inland Empire Utilities Agency
The Chino Basin is a large alluvial groundwater basin in Southern California with storage exceeding five million acre-feet. Groundwater in the Chino Basin generally flows from the forebay regions in the north towards the Prado Flood-Control Basin in the south (“Prado Basin”). Depth to groundwater is relatively shallow in the Prado Basin area, which allows for groundwater/surface-water interaction.
The Chino Basin Watermaster, the agency responsible for groundwater basin management, implements aggressive groundwater-supply programs that include controlled overdraft and the possibility of causing groundwater-level declines in the basin. The EIR for the groundwater-supply program identified the lowering of groundwater levels as a potentially adverse impact on the Prado Basin’s riparian vegetation that consumptively uses shallow groundwater.
Our team developed the monitoring and reporting program and has recently begun its implementation. The first step was to design, drill, construct, and develop 16 monitoring wells located near the riparian habitat to track changes in groundwater levels within the shallow or perched aquifer systems. The monitoring program also includes characterization of the extent and quality of the riparian habitat over time, which required the acquisition and analysis of remote-sensing data from the Landsat program, high-resolution aerial photography, and field vegetation surveys. The program also involves monitoring all factors that could potentially impact the habitat (not only changes in groundwater levels), including surface-water discharge, precipitation, temperature, wildfire, and pests, among others. Lastly, the program includes groundwater-flow model projections of future drawdown to identify areas of prospective impacts on riparian habitat. In 2017, the Watermaster published the first annual report, which identified no current or future adverse effects on the riparian habitat and recommended certain refinements to the monitoring program.