Todd Engineers

Key Issues
Sustainability of groundwater supply Effective management of groundwater storage Role of water recycling Salinity management

The City of Corona relies on local groundwater within their water service area for almost one-half of their water supply. In order to more actively manage this limited resource, the City retained Todd Engineers to prepare a Groundwater Management Plan (GWMP). The plan follows guidelines set forth in Assembly Bill (AB) 3030, as amended by Senate Bill (SB) 1938, which provides additional GWMP requirements. Such a plan allows the City to address issues of groundwater recharge and storage, critical components for effective management of the local subbasins and the City’s water supply.

Todd Engineers conducted an extensive basin-wide hydrogeologic investigation that identified and mapped key aquifers, evaluated groundwater quality both spatially and over time, and developed a water balance of inflows, outflows, and change in storage for the groundwater subbasins. The assessment provided for a perennial yield for the basins and indicated that future projections of groundwater pumping could not be sustained without enhanced groundwater recharge.

Twenty-five groundwater management strategies to accomplish the basin management objectives were identified and evaluated. Many strategies supported the enhanced recharge of various water sources including stormwater, recycled water, and excess imported water. The plan also included an assessment of potential groundwater recharge locations for recycled water for Lee Lake Water District in the Bedford Subbasin.

Management strategies were evaluated with a numerical groundwater flow model, constructed by Todd Engineers for the project The evaluation identified changing components of the water balance associated with management strategies and indicated that no one strategy would accomplish management objectives. As such, a comprehensive program was recommended that incorporated a combination of strategies to be implemented over the next seven years. The Groundwater Management Plan was adopted by the City on June 18, 2008.

Services Provided
Investigation of hydrogeology Water balance analysis Numerical modeling Salt loading analysis Evaluation of management strategies Preparation of AB 3030 Groundwater Management Plan

Currently, the City of Corona is working with regulators and other local agencies to protect water quality and encourage the conjunctive use of imported water in the Santa Ana River Basin. As part of this effort, the City is participating in a study to determine whether intentional recharge of imported water may have a significant impact on the salt balance.