Conservation Work Continues in Yolo Bypass Wildlife Area

Ducks Unlimited oversees construction activities during the third year of a proposed four-year-long construction project in California’s Yolo Bypass Wildlife Area (YBWA).

The most significant portion of the current phase consists of DU staff overseeing the excavation of approximately 70,000 cubic yards of material from Greens Lake. DU Regional Biologist Aaron Will secured funding from multiple state and federal agencies over the last eight years to complete this multi-year project that will utilize over $6 million in funding to complete.

Greens Lake, silted in over the last several decades, has become increasingly shallow and is inundated with invasive vegetative species. The lake contains water year-round, so the excavation must be completed in submerged conditions utilizing long-reach excavators. The contractor was required to remove and separate the aquatic invasive species before soil excavation activities. Next, the contractor removed soil from Greens Lake and stockpiled material to allow it to dry before utilizing the material for public access roadway improvements.

The excavation of Greens Lake will remove invasive species such as Primula vulgaris (common primrose) and Pontederia crassipes (common water hyacinth). Currently, Greens Lake only reaches a maximum depth of approximately 6 feet. The soil excavation will occur near the western and eastern shorelines to create a depth of roughly 10 feet along the eastern and western shorelines.

DU will create deeper water habitat to benefit various species of fish, waterfowl, shorebirds, and giant garter snakes, a state and federally listed threatened species. The goal of the deeper water habitat is to inhibit the growth and establishment of invasive aquatic species, provide deeper, cooler water for fish species to survive during the summer months, and provide a more open water habitat for waterfowl species. Adding more open water habitat will benefit the threatened giant garter snake by providing a greater area for foraging.

The excavation of deeper channels in Greens Lake will also help the YBWA staff to achieve two critical goals. The YBWA staff will be able to flood up waterfowl and shorebird habitat more efficiently during the fall, winter and spring, and help remove water from the wildlife area in the winter during significant flood events.

The YBWA is immediately west of the City of Sacramento. During flooding, the YBWA is designed to become a manageable floodway to reduce the potential of flooding in the Sacramento River and the City of Sacramento. During significant flood events, the entire 17,000-acre YBWA may be covered by flood waters, and in some places, flood water could reach 10 feet deep or more. This project will help to move flood waters across the YBWA more efficiently to restore public access.

It is estimated that the YBWA will provide an additional seven days of public use access during the waterfowl season because of this multi-year project.

Material excavated from Greens Lake will be placed on public-use roadways in the wildlife area. The material will be graded and compacted to allow for driving and walking by the public. The elevated roads should prevent flooding after being raised several feet higher, allowing for better public access and reducing the number of days the wildlife area must close due to flooding. Improved roads will be completed with a top layer of gravel to enhance hunter and wildlife viewing accessibility during winter. DU is also replacing and installing 12 culverts and water-control structures to increase the ability to flood managed seasonal wetlands and rice fields in the wildlife area and aid in drainage of the wildlife area during winter flood events.

Numerous environmental permits are needed to perform these activities, including forms from the U.S. Army Corps of Engineers, Central Valley Flood Protection Board, Central Valley Water Quality Control Board, US Fish and Wildlife Service, California Department of Fish and Wildlife and the National Marine Fisheries Service. Due to permitting conditions related to water quality, nesting birds, and the threatened giant garter snake, construction activities are limited from May to September each year.

Next year will be the last phase of this project. It will include the installation of a new pump station to help dewater flooded areas of the wildlife area to improve hunter access during waterfowl season and wildlife viewing opportunities during the winter months.

Ducks Unlimited Inc. is the world's largest nonprofit organization dedicated to conserving North America's continually disappearing waterfowl habitats. Established in 1937, Ducks Unlimited has conserved more than 15 million acres thanks to contributions from more than a million supporters across the continent. Guided by science and dedicated to program efficiency, DU works toward the vision of wetlands sufficient to fill the skies with waterfowl today, tomorrow and forever. For more information on our work, visit www.ducks.org.