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Colusa County Multi-Benefit Groundwater Recharge

Colusa County Multi-Benefit Groundwater Recharge Program

Farming for Sustainable Groundwater and the Flyway

Working in partnership with the Colusa Groundwater Authority, The Nature Conservancy is conducting an on-farm, multi-benefit program, which provides an opportunity for growers to receive financial compensation for recharging groundwater in the course of normal farming operations on a variety of crops while also providing critical “pop-up” wetland habitat in early fall when water is scarce on the landscape and shorebirds migrating along the Pacific Flyway often have nowhere to stop over on long migrations.

This on-farm recharge program requires short-term commitments from growers to irrigate and maintain shallow depths of 4” or less on enrolled fields. The program pays for field preparation, irrigation and water costs.

Site Selection Criteria

Fields will be selected based on how well they meet conditions for providing multiple benefits. We are looking for sites that are suitable for groundwater recharge and can also provide high-quality, open (non-orchard) wetland habitat suitable for bird stopovers when flooded.

The selection criteria include soil types conducive to recharge, crop types suitable for recharge, fields that can be flooded post-harvest to provide “pop-up” wetland habitat, and appropriate water sources.”

Colusa County Multi-Benefit Recharge Program Area Map

This map shows areas that have been approved by the California Department of Water Resources (DWR) for the program. DWR is overseeing and partially funding this program as part of its Sustainable Groundwater Management Grant Program.


The setup and implementation dates are somewhat flexible. Water spreading will take place between Aug. 15 -Oct. 15, with set up taking place earlier. Timing will vary depending on water availability and crop schedule. Let us know what will make these practices workable with your crop production schedules!

July 1-August 15
Application: (1) Let us know your field location and availability, crop types, and timing by phone or email, (2) Fill out the 1-page application and attach a map and 10-year crop history.

Selection: TNC selects fields based on soil and crop type and timing.
Field Verification: TNC verifies suitable conditions.
Contracting: Selected participants sign contracts with TNC.
Field Setup: (1) Engineers will survey the field and install pressure transducers or flow meters at inlets and outlets and in adjacent wells to measure water and groundwater depths. (2) Field prep to remove or incorporate vegetation may be recommended. (3) Soil and water samples collected to monitor impacts on water quality. (4) Installation of wooden stakes to monitor water depths and bird presence.

Implementation: (1) Participants spread water on fields for 4-6 weeks, maintain shallow depth (4” maximum), and record changes in water flow on an irrigation log. (2) TNC records field depth and bird presence. (3) Consulting engineers monitor water delivery and changes in groundwater depth.

Payment: Contract fees paid after completion of program requirements.

Required Water Management

BirdReturns requires participants to maintain shallow-flooded conditions – saturated soil on the entire enrolled acreage and no more than 4″ depth.

Growers may use surface water or groundwater (or a combination of both) to maintain water on their enrolled field.

Required Field Conditions

BirdReturns requires participants to achieve certain field conditions, mainly by performing post-harvest mechanical treatment(s) which disrupt the soil and encourage straw-soil mixing and straw decomposition so that the field is free of standing vegetation or matted straw. For rice fields that do not already provide suitable migratory bird habitat with their typical practices, some modifications or additional treatments may be required to create suitable habitat. Thus, proper straw management is a critical component of this program’s success and TNC’s ability to continue this incentive. 

Rather than prescribe a specific practice, TNC is attempting to maintain flexibility by describing the desired field conditions and allowing growers to implement any one of the following practice combinations after harvest:

Chop + Disc + Roll

Chop + Disc 2x

Good Field Condition Examples

Poor Field Condition Examples

clumps a bit big, but pretty good


Good field conditions, though clumps are slightly larger than ideal. © Migratory Bird Conservation Partnership

too much standing stubble deep field


Too much standing stubble and water that is too deep. © Migratory Bird Conservation Partnership


Ideal bird habitat with mudflat-like conditions. © Migratory Bird Conservation Partnership


Too much undecomposed rice stubble. © Migratory Bird Conservation Partnership


Great flooded habitat, attracting lots of birds. © Migratory Bird Conservation Partnership


Too much straw and stubble. © Migratory Bird Conservation Partnership