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Yolo Bypass Study Highlights Big Payoff for Small Cost

September 2015
Yolo Bypass

Significant habitat improvement is possible for several fish and bird species with little annual economic cost for farmers according to a three-year study of the Yolo Bypass, led by Delta Independent Science Board Chair Jay Lund and then-graduate student Robyn Suddeth (now a Water Policy Analyst with CH2M Hill).


“This study highlights the ability for birds and fish to both benefit from management of a mixed agricultural and wetland landscape, without large tradeoffs among them,” said Suddeth in the executive summary of the study, Integrating Ecosystem, Flood Control, Agricultural, and Water Supply Benefits: An Application to the Yolo Bypass that ended in July 2014. “Importantly, agricultural crops are optimally a vital component of the overall habitat mosaic, a sign that even heavily modified floodplains can be improved for native species without eliminating human use.”


The study, funded by the Delta Stewardship Council (Council), as part of its Delta Science Fellows Program will assist the Council in furthering the achievement of the State’s coequal goals, in particular the rehabilitation of the Delta’s ecosystem, as the study highlights how birds and fish can benefit from management of a mixed agricultural and wetland landscape without large tradeoffs. The study suggests that even heavily modified floodplains, such as the Yolo Bypass, can be improved for native species without eliminating human use.


The Yolo Bypass is considered one of the more promising sites for habitat restoration in the Bay-Delta system because of its large size and many known benefits for fish and waterfowl species.


A comprehensive habitat restoration plan for the bypass requires understanding across a broad range of topics, including farming practices, agricultural economics, waterfowl and fish usage of the floodplain, flooding frequency and extent, and groundwater recharge and use. To achieve this understanding, researchers drew from invertebrate studies, agricultural data and interviews with area landowners and waterfowl managers. Researchers coupled this knowledge with computer models to develop strategies for managing flows across the bypass with assessment of farmer’s crop revenue reduction due to delayed planting and land use change.


Suddeth developed a new model – the Yolo Bypass Multiobjective Optimization Model – that can help provide detailed information about the economic implications of management decisions, and a rough estimate of ecological and economic gains or losses resulting from any changes.


Using the model, researchers learned that agricultural land uses can contribute to fish and bird habitat quality at very little cost, as long as flooding is optimized in space and time. Significant improvements in habitat quality are achievable with additional land use changes and $100,000 - $200,000 in annual net revenue losses or compensation. This loss in annual revenues represents less than a one percent loss of total annual crop revenues on an economically optimized (modeled) bypass.


“The model informs decision makers in Yolo Bypass projects of any additional flow that may be brought onto the Bypass in future years for fish and/or bird habitat, with the assumption that some kind of notch or other way of bringing those flows onto the floodplain will eventually be built,” Suddeth said.


Researchers also discovered that the agricultural land uses best suited to serve a dual purpose as habitat are rice, wild rice, pasture, and fallow fields. The study suggests it might be worthwhile to grow additional acres of rice and wild rice as habitat and that the cheapest way to improve habitat is to exchange some pasture in the southern bypass for wetlands.


To learn more about this study, please click here.

Coequal goals

The Delta Stewardship Council was created in legislation to achieve the state mandated coequal goals for the Delta. "'Coequal goals' means the two goals of providing a more reliable water supply for California and protecting, restoring, and enhancing the Delta ecosystem. The coequal goals shall be achieved in a manner that protects and enhances the unique cultural, recreational, natural resource, and agricultural values of the Delta as an evolving place." (CA Water Code §85054)