Delta Twin Tunnels project is the missing link to a secure and sustainable water system in California.
California Department of Water Resources (DWR) has open a public comment period for their modified Bay Delta Conservation Plan Draft Environment Impact Report. While many aspects of Bay Delta Conservation Plan have been changed, the controversial twin tunnel conveyance proposal remains a central feature of the project. Known within the plan as the Waterfix, DWR describes the twin tunnel concept like this –
The proposal involves construction of three new intakes, each with a maximum diversion capacity of 3,000 cubic feet per second, on the east bank of the Sacramento River between Clarksburg and Courtland in the north Delta. Each intake site would employ state-of-the-art on-‐bank fish screens and, although the diversions would be located outside of the main range for delta and longfin smelt, the fish screens would be designed to meet delta smelt criteria. Two 40-foot-wide underground pipelines would carry the diverted water by gravity flow approximately 30 miles to the expanded Clifton Court Forebay, where two pumping plants would be constructed to maintain optimal water levels in the forebay for the existing State Water Project (SWP) and Central Valley Project (CVP) pumping facilities. Those existing pumps would lift the water into the canals that flow hundreds of miles to supply San Joaquin Valley farms and cities as far away as San Diego. – What is California Waterfix?
I am perhaps an anomaly in Northern California in that I support the twin tunnel project. I came to the conclusion that the best way to stabilize the Delta environment and move CVP and SWP water from north to south is the proposed twin tunnel project after years of researching the history of the Delta and both the federal and state water projects. In short, both a peripheral canal or tunnel conveyance structure have been proposed since the beginning of the federal and state water projects. The tunnels are not a new concept and one that engineers and environmentalists have supported in the past as a way to mitigate the disastrous consequences of attempting to move millions of acre feet of water through the Delta to farmers and residents in the south. We are now witnessing the ecological collapse of the Delta from a lack of a proper canal or tunnel to transfer the water from north to south.
The following are my comments in support of the twin tunnels of Bay Delta Conservation Plan.
Delta twin tunnels are last link in the California water system
No discussion about the future of the Delta can be complete without a good understanding of the historic proposals for this estuary. Since the early planning stages of the Central Valley Project of the 1930’s, it has always been proposed that some sort of Delta Cross Canal or tunnel be built to transport water either around or under the Delta.
With respect to fresh water inflows into the Delta, history shows that before the several dams of the Central Valley Project (CVP) were completed in the 1940’s, salinity intrusion into the Delta was a serious problem during times of drought.1 Since the CVP started releasing water into the Sacramento River, Delta farmers have had a more dependable supply of high quality irrigation water, even during high tides and low rain fall years.
One of the goals of the CVP was to provide fresh water to flush out the brackish water that creeps into the Delta during high tides.2 But another element of the CVP that was never built was a Delta Cross Canal. Water was to be pumped out of the Sacramento River, below Sacramento City, and conveyed along the eastern edge of the Delta through improved sloughs and man-made canals to the pumping stations on the south side of Delta.2
In 1957 the California Water Plan issued by the Department of Water Resources envisioned a more elaborate project to move water around the Delta named the Trans-Delta System. At its heart the Trans-Delta System would have had control structures on the Sacramento River and Steamboat Slough to divert water into the Delta Cross Channel located below Walnut Creek and then into a Delta Cross Canal.3 Another element was a siphon under the Sacramento River east of Collinsville that would deliver water near Antioch. Known as the Antioch Crossing, the proposed siphon tunnel was to be 3,000 foot long with a diameter of 25 feet. The overall length of the Antioch Cross project was to be 33 miles in length and have capacity of 17,000 second-feet and transport 11,250,000 acre-feet of water per season.4
Both the CVP and California State Water Project (SWP) engineers understood that the Delta could never handle the volume of water it was being asked to transfer from north to south for an indefinite period of time without damage to the Delta itself. Only because this tidal estuary was reclaimed during the 19th and 20th centuries was it minimally suited to aid in the transport of water from the north side of the Delta to the south side. Had the thousands of miles of levees not been built along rivers and sloughs in Delta, the Central Valley Project would have had to build a canal around the Delta.
The CVP and SWP have provided flood protection for Sacramento Valley communities and helped maintain high quality fresh water in the Delta to be used by farmers to grow crops. The large amount of fresh water released into the Delta from the Sacramento River and the export of a like amount of water to the southern end of the Delta has contributed to what scientists tell us is an ecological disaster for the Delta’s fisheries. This combined with the fragility of the Delta levees susceptible to collapse from either earthquake or flood makes the construction of the proposed twin tunnels project almost a necessity.
Opponents of any Delta Cross Canal or Tunnel need to realize that vast amount of water conserved behind the CVP and SWP dams is under contract to irrigation and water districts south of the Delta. The dams of Folsom, Oroville, Shasta and Trinity were specifically built to release water during the summer for farmers and residents in the San Joaquin Valley and Southern California. It is unfortunate that a conveyance project across the Delta was never built under the CVP or SWP.
While I don’t always agree with how either the San Joaquin Valley farmers or Southern California residents use the water that is exported to them, that doesn’t negate the fact that they have a contract for the delivery of the water. They are not stealing or grabbing Northern California water. They are buying the water stored behind dams constructed expressly for that purpose.
It’s time to build the missing links of California’s water system and construct the most environmentally responsible proposed project to date for conveying water across the Delta: the BDCP twin tunnels
- Sacramento-San Joaquin Delta Atlas, page 53, State of California Department of Water Resources, August 1987.
- The Central Valley Project, page 125, California State Department of Education, 1942.
- Bulletin No. 3 The California Water Plan, page 186, California Department of Water Resources, May 1957.
- Bulletin No. 3 The California Water Plan, page 187, California Department of Water Resources, May 1957.
July 24, 2015
Kevin Knauss
Granite Bay, CA 95746
Other blogs I’ve written on the Delta-
- Peripheral canal starts pumping water around the Delta
- Comparing Delta tunnels to deep water shipping channel
- Tunnel or restore the Sacramento – San Joaquin Delta
- Let the Sacramento – San Joaquin Delta go natural
Download -> [wpfilebase tag=fileurl id=757 linktext=’California WaterFix DWR Twin Tunnels FAQ’ /]