The University of California, Davis and Point Blue Conservation Science partnered with the California Rice Commission to create a “Rice Footprint” – a comprehensive outline of how the California rice industry impacts ecosystems, wildlife, and communities, and how many acres of rice are needed for them to thrive. The editors of this interdisciplinary report were John M. Eadie and Daniel S. Karp, both of UC Davis, with contributions made from over a dozen scientists from disciplines spanning economics, ecology, and wildlife biology.
A Conservation Footprint for California Rice was made public in early 2025 and highlighted the critical role of rice agriculture in California for wildlife conservation and the economy. Rice fields, especially winter flooded ones, act as surrogate wetlands supporting diverse species, including Giant Gartersnakes, waterfowl, shorebirds, Sandhill Cranes, and native fishes. However, challenges such as climate change, water availability, crop market shifts, and urban expansion threaten these habitats.
There were 4 main questions this report sought to answer:
- How much rice should be planted to meet minimum requirements for species of conservation concern in California’s Central Valley?
- How much planted rice needs to be managed in ways that provide ecological benefits (i.e., winter flooding)?
- Are there specific locations where rice has the highest potential to maintain high levels of wildlife abundance and diversity?
- Which management practices are the most economically feasible and create the highest net positive benefits to the greatest number of species?
- Wildlife Conservation Needs:
Priority areas include Colusa, Sutter, Yolo basins, and bypasses near wetlands and wildlife refuges.
For the Giant Gartersnake: 83, 634 acres of planted rice is needed to satisfy the recovery plan target habitat goals. Requires 80,000 acres of flooded rice near wetlands for recovery plan for the species.
For Waterfowl: Needs 500,000 acres of planted rice, with 257,727 acres winter flooded, under high-competition loads.
For Shorebirds & Black Terns: Require 472,794 acres of planted rice for breeding and 373,540 acres of winter flooded rice for non-breeding.
For Sandhill Cranes: Need 43,139 acres of flooded rice for roosting.
Native Fishes: Require 30,000 planted rice acres in Yolo and Sutter bypasses.
- Rice Management Practices
For almost every species considered, winter-flooding is a vital part of the annual life cycle. for most species, though water depth and timing present conflicts. The optimal water depths for each species vary, ranging from 0–4 inches for shorebirds to >10 inches for native fishes. While early fall flooding benefits shorebirds, delayed spring draining can support ducks in the spring.
- Economic Contributions
The California rice industry is central to the rural economy of not only the Sacramento Valley, but across the entire state. Rice agriculture generates over $1 billion annually and supports over 7,500 jobs when at peak production. It also provides myriad recreational opportunities for birdwatchers, hunters, and outdoor enthusiasts and creates a food base for waterfowl. Replacing the food base for waterfowl provided by winter-flooded rice would require an additional 255,000 acres of managed wetlands at a cost of nearly $2.8 billion in 2010 dollars (Petrie and Petrik 2010).
There were several economic factors to consider when determining the desired number of rice acres to support wildlife conservation in the Central Valley. It is a challenging task to evaluate the social and economic capital necessary to support these ricelands and wildlife-friendly management practices. However, public willingness to pay for conservation is significant, with estimates ranging from $106–$572 per household for species protection.
- Threats
The report found that potential threats to achieving the necessary rice acreage to maintain peak wildlife conservation activity would be drought and water costs. These pose the greatest risks to rice acreage, with planted acres dropping to 250,000 during severe droughts. Conversion to other crops, such as orchards, is not considered a threat to acreage due to soil constraints.
- Next Steps
The next steps of this interdisciplinary project are to 1) conduct multi-objective decision analyses to optimize conservation efforts; 2) improve mapping of water depths and management practices; and 3) expand research on underrepresented species and their compatibility with rice management.
To Sum it up:
California’s rice fields are indispensable for wildlife conservation and the statewide economy. A conservation footprint of 470,000–500,000 acres is recommended to sustain multiple species, with strategic management practices and stakeholder collaboration being essential for long-term success. For further reading, the full report can be accessed at https://www.calrice.org/rice-footprint.