Monitoring with Lysimeters to Assess Regulatory Compliance with Recycled Water Recharge

Lysimeters head assemblies
on the levee above
the recharge basin

Inland Empire Utilities Agency

The IEUA, the Chino Basin Watermaster (CBWM), the Chino Basin Water Conservation District (CBWCD), and the San Bernardino County Flood District (SBCFD) are working together to expand and improve 19 recharge basins to enhance the agencies' ability to capture and recharge stormwater, recycled water, and imported water. These sources of water supply will be recharged into the Chino groundwater basin and will ensure the stakeholders that the region is drought-proofed to the greatest extent possible.

With the efforts of the IEUA, the recharge basin enhancement and expanded recycled water projects will produce 95,000 acre-feet of new water annually, enough to meet the needs of 300,000 new residents. Recharging recycled water into a potable groundwater basin, required that the current Basin Plan had to be first reviewed, evaluated, and ultimately amended. Secondly, the groundwater quality objectives for the basin had to be raised through a rigorous methodology that was consistent with state law.

The DHS has been developing draft regulations for the recharge of recycled water. Early versions of these proposed regulations required the project proponent to drill and install monitoring wells in the recharge "mound" beneath the recharge basin to demonstrate the reduction of total organic carbon and total nitrogen to concentrations specified in the permit.

WEI installed lysimeters in the bottom of the recharge basins to ensure that samples collected while the recharge basin is being operated are truly representative of the recharged water.

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