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Development and Application of High-Resolution Models to Recalculate the Chino Basin Safe Yield and Follow-on Model Applications

Chino Basin Watermaster

Map of groundwater resources within the Chino Basin

The Chino Basin adjudication was settled in 1978 through a stipulated agreement. Through other agreements, the Chino Basin Watermaster was required to recalculate the safe yield and other hydrologic items in 2011. Our groundwater team developed and implemented a methodology based on scientific principles and detailed numerical models to develop a complete hydrologic description of the Chino Basin over the 1960-2011 calibration period and the 2012-2071 planning period.

Watermaster was also required to calculate net Santa Ana River recharge and how the net Santa Ana River recharge changes with groundwater pumping and storage management. Working with Watermaster staff and legal counsel, our team participated in a series of workshops and two-day peer review sessions to thoroughly review the methodology, assumptions, data, and computational results. The resulting model was praised during the peer review process as one of the most comprehensive and thoughtfully developed groundwater models ever built to manage a groundwater basin. Watermaster and the Court accepted the technical work and the recalculated safe yield.

The model was updated and used to develop a storage framework (management) plan for up to 1,000,000 acre-feet of water banking activities, to develop an updated Salt and Nutrient Management Plan for the basin, and to estimate the impacts of groundwater management activities on surface water discharge and riparian habitat in the Prado Reservoir area and upstream habitat areas along the Santa Ana River. The model is currently being updated to include a subsidence module and is being recalibrated to estimate the safe yield for 2021 through 2030.

Team Spotlight

Garrett Rapp, PE

Associate Engineer II

Eric Chiang

Principal Scientist II