The Delta is dying and so are the historic salmon and steelhead runs in California. More than half of the historic water flows into the Delta from the Sacramento and San Joaquin Rivers are diverted. The State Water Board is proposing some major changes. Learn about the issues and what you can do to get involved. Here are links to several useful sites to help get you started:
After studying the water flows needed for the recovery of chinook salmon and steelhead spawning runs in the central valley rivers for several years, the Water Board is recommending increasing flow on the San Joaquin River and its tributaries to a range of 30 to 50 percent, with a starting point of 40 percent of unimpaired flow from February through June. This is less than the 60 percent of unimpaired flow recommended by their scientific advisory panel. Unimpaired flow represents the water production of a river basin, unaltered by upstream diversions, storage, or by export or import of water to or from other watersheds. Historical median February through June flows from 1984–2009 in the Merced, Tuolumne, and Stanislaus Rivers were, respectively, 26, 21, and 40 percent of unimpaired flow. In other words, half of the time more than 60 or 70 percent of each river’s flow is diverted out of the river during these months.
Scientific studies show that flow is a major factor in the survival of fish like salmon and that current flows are inadequate to protect many endangered and threatened species, as well as species relied upon by the commercial fisheries. The Draft SED recognizes that other factors, like predation and loss of habitat, affect fish populations, and those factors are also addressed in the Draft SED.
The unimpaired flow requirement is designed to mimic the cues of nature that species have evolved to respond to, but is not intended to be a rigid and fixed percent of unimpaired flow. It is intended to provide a quantity of water as a baseline, but the proposal provides for, and encourages, collaboration to use the flows as a block of water that can be “shaped” or shifted in time to provide more functionally useful flows that provide increased habitat, more optimal temperatures, or a migration cue. This type of targeted effort can provide more timely and efficient use of flows than a set regime.
The Draft SED recognizes the financial and operational challenges to local economies of reduced diversions. The flow requirement considers the needs for fish and wildlife along with the needs of agriculture and local economies.
This video developed by PPIC provides an overview of changes and challenges to the fragile Delta.