Efforts to enhance the food supply for the protected delta smelt are showing initial success, according to wildlife and water resources experts. They gathered at the Yolo Bypass to the Sacramento River last week to discuss their work to increase the number of plankton available to the fish.
Cooperative efforts by state and federal agencies, Sacramento Valley farmers and water providers have resulted in the creation of a phytoplankton bloom, the experts said. Phytoplankton are microscopic creatures and the major food source for zooplankton, another minuscule creature that represents the main food source for delta smelt.
The smelt, listed as threatened under the federal Endangered Species Act, lives only in the Sacramento-San Joaquin Delta and has been at the center of debate about how much water should be reserved for it and other protected fish.
By increasing the two levels of plankton, the researchers and other cooperators have successfully increased available food for the smelt, said Ted Sommer, lead scientist for the California Department of Water Resources.
“This effort provides a good example of the application of scientific research to address complex management issues,” Sommer said. “The overall strategy of the smelt plan was based on an intensive effort by a multi-agency team to isolate the major factors affecting different life stages of delta smelt and to identify the habitat, environmental and landscape conditions that could be improved to support better growth, health and reproduction.”
The plan led to a cooperative effort earlier this summer among state and federal governments, water agencies and other partners along the Sacramento River, including the Glenn-Colusa Irrigation District, Reclamation District 108, Reclamation 2035, Knaggs Ranch and Conaway Ranch. The Tehama-Colusa Canal Authority and the U.S. Bureau of Reclamation assisted, along with other agricultural partners in the Sacramento Valley.
The result was a redirection of water from the Sacramento River down the Colusa Basin Drain, through the Knights Landing Ridge Cut Slough, past Wallace Weir, through the Yolo Bypass and into the delta, to provide optimal conditions to create the critical food source for growing delta smelt. Sommer said a recent, substantial delta plankton bloom at Rio Vista indicates this strategy was effective in boosting downstream food-web resources for smelt.
He added that the program was accomplished without the use of any additional water; rather, it was done by rerouting the water through the Yolo Bypass and then returning it to the Sacramento River for other uses.
“Acting on a scientific hunch with cooperation that extended deep into the Sacramento Valley, we moved quickly to see if we could boost the delta smelt food supply in the western delta in this fifth year of drought,” said Charlton Bonham, director of the California Department of Fish and Wildlife. “The results surpassed our expectations and give us hope that in future years we can relatively quickly and easily take advantage of the Yolo Bypass floodplain to improve conditions for a species on the brink of extinction.”
Chris Scheuring, an environmental attorney for the California Farm Bureau Federation who attended last week’s event, called it an encouraging sign to see smelt-restoration efforts focus on something other than river flows alone. Scheuring said food supply and other variables might have application in protecting not just the smelt, but other species at risk, such as salmon that use the river systems.
“The delta smelt has been on the ropes for some time now, and the flow-centric approach to stabilizing and improving the species numbers has clearly not worked. At the same time, it has hamstrung the operations of the water projects in the south delta,” he said.
“Much more is at play in the delta smelt’s troubles than just the availability of water in the estuary,” Scheuring said. “A complex of factors is likely involved, and just throwing water at the problem has not worked.”
He credited the agricultural water districts involved in the project with recognizing the complexity of the science affecting fish population, and for taking “a proactive and holistic approach to conservation.”
The general manager of one of the districts involved in the project, Lewis Bair of Reclamation District 108, said partnerships among government agencies, environmental organizations and local water districts are “making a difference” for birds, fish and farms.
“There is not one simple solution to save the smelt, but a complex set of challenges which must be identified and addressed to secure smelt survival,” Bair said. “This is why we are actively working to implement this part of the Delta Smelt Resiliency Strategy in the Sacramento Valley—providing vital nourishment and improving habitat in the Yolo Bypass for smelt to thrive and reproduce.”
David Guy, president of the Northern California Water Association, said the cooperative effort benefits all Californians.
“It is critical—and possible with these partnerships—to improve fish and wildlife habitat through the efficient use of our region’s water resources while managing a productive farm economy,” Guy said. “The drought has not only impacted smelt, but it has also affected the ability to deliver water for farms, wildlife refuges and recreation throughout the region. Farmers and the rural communities throughout the Sacramento Valley care deeply about our rivers, they understand how the rivers function and they have made significant investments in efforts to preserve and improve fish and wildlife habitat.”
Steve Adler is associate editor of Ag Alert. He may be contacted at firstname.lastname@example.org. Permission for use is granted by the California Farm Bureau Federation.