Water-Musings: Delta Flows

In 2019, The Bay-Delta Plan is being updated through two separate processes (Plan amendments). The first Plan amendment is focused on San Joaquin River flows and southern Delta salinity. The second Plan amendment is focused on the Sacramento River and its tributaries, Delta eastside tributaries (including the Calaveras, Cosumnes, and Mokelumne rivers), Delta outflows, and interior Delta flows.

12/18/19: Updates to Proposed Amendments are posted at: https://www.waterboards.ca.gov/waterrights/water_issues/programs/bay_delta/

Additionally, SWRCB posted a Frequently Asked Questions (FAQ) for the Bay Delta Plan UPdatew and Its Anticipated Impacts to Agriculture, Water Supply and Wildlife https://www.waterboards.ca.gov/waterrights/water_issues/programs/bay_delta/docs/bay_delta_faq.pdf

The FAQ answers the question: How much fresh water flow increase is recommended and how much will water supply be decreased?

“The Lower San Joaquin River flow proposal as adopted would provide a range of 30 to 50 percent of unimpaired flow from February through June in the Merced, Tuolumne, and Stanislaus rivers. The starting point is proposed to be 40 percent of unimpaired flow. This is not the same as a 40 percent reduction. The 40 percent unimpaired flow proposal would result, on average, in a 14 percent reduction in surface water supply for human uses like agriculture and drinking water, and an average 26 percent increase in instream flows on the Merced, Tuolumne, and Stanislaus rivers.”

10/21/16: A report is recommending drastic increases in: inflow requirements, non-flow mitigations, and Delta outflow requirements. There are recommended timings of cold water releases from reservoirs and increased storage of adequate water in reservoirs to be able to provide critical at other times. The report also documents the decline of key Delta fish species, reductions of winter and spring flows over time, the need for more fresh water in the Delta, and the need for increased Delta outflow.

California’s Water Quality Control Board is seeking comment on the Scientific Basis Report, from which it will determine the necessary flows to “protect fish and wildlife beneficial uses.”

Written comments are due by Dec. 16 and a workshop at which oral comments can be made is scheduled Dec. 7. http://www.swrcb.ca.gov/press_room/press_releases/2016/pr101916_bay_delta.pdf