[env-trinity] Trinity Journal; BOR: 'Lake storage going to be a tough go'
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Thu Oct 30 21:21:47 PDT 2014
BOR: 'Lake storage going to be a tough go'
By Sally Morris The Trinity Journal | Posted: Wednesday, October 29, 2014 6:15 am
Area Manager Brian Person of the Northern California Area Office of the U.S. Bureau of Reclamation recently offered a historic overview on how the Trinity River Division of the Central Valley Project came to be back in 1955 as he updated Trinity County supervisors on current operations and challenges presented by severe drought conditions.
He noted that while the vast majority of precipitation occurs in the northern part of the state, the vast majority of people settled in the southern part “which creates disparity. California has the most complex system of water distribution in the world with state, federal and some local projects. The state is very well-plumbed.”
Six major storage reservoirs in the state hold a capacity of 11 million acre-feet of water with Shasta and Trinity accounting for 7 million of it. In an average year, 1.2 million acre-feet of water flows into Trinity, but this year the number was only 300,000.
Person spoke of the early years after Trinity Dam was completed in 1966 when 11 percent of the water went into the river and 89 percent was exported to the Sacramento River basin through the Clear Creek tunnel. Impacts to the fishery were almost immediate as the broad Trinity River floodplain “became a canal and the vegetation berm built up,” he said.
Thus began the monumental flows studies, the Central Valley Project Improvement Act of 1992 that furthered those studies, the Trinity River Restoration Program and the 2000 Trinity River Record of Decision that increased the flow regime to the Trinity River based on water year type forecasted in April. The ROD also called for mechanical restoration at 47 sites and the introduction of coarse sediments, also blocked by the dam, which fish need to spawn.
Over time, the diversions of Trinity River water to the Sacramento River basin have decreased to a rough ratio of 53 percent to the Sacramento and 47 percent to the Trinity River, Person said, noting there were years that defied the trend, including 2010 when 29 percent went to the Sacramento River and 71 percent down the Trinity. The ratio is supposed to be roughly 50/50 over time.
With some reports this year indicating nearly 80 percent of the diversions have gone to the Sacramento, Person said the actual diversion has been 58 percent this year, resulting in a dramatic drawdown of the Trinity reservoir.
“It wasn’t based on inflow. It was based on drawdown of the storage and unless we get a decent winter and some refill, we can’t repeat that operation next year,” he said, adding the Shasta Lake reservoir has much greater potential to refill in one year as it is fed by three rivers and that is taken into account in determining the dam releases and reservoir drawdown.
Person said the jury is still out on whether emergency augmentation flows of cold water released from Trinity in late August helped prevent a massive fish die-off in the lower Klamath River like the one in 2002 when at least 34,000 fish died as a result of low flows, warm water and Ich disease that flourished in those conditions.
He said that “despite the releases made this year, Ich did come in, there are fish infected, they are greatly stressed and we hope they make it to spawning time.”
With Trinity Lake now only about 23 percent full when last year it was 51 percent full at this time, Person said “the lake storage is going to be a tough go. It has very low likelihood of full refill.”
“We recently heard from the Whiskeytown Park superintendent about all the benefit of the full pool at Whiskeytown all summer and we sort of cringe knowing the water comes from Trinity,” said Sup. Judy Morris.
Person said Whiskeytown only holds 250,000 acre-feet of water and it is only lowered in October as a flood buffer heading into winter.
“There isn’t much water there. We use it to help maintain cold temperatures in the Sacramento, but it is such a tiny component, there isn’t much benefit in changing it and it pays the bills through the power plant. The bottom line is we’ve looked at not filling Whiskeytown or drawing it down sooner, but it just isn’t much water. Trinity is a storage reservoir and Whiskeytown just absorbs fluctuation. It stores only 10 percent of the water that Trinity does,” he said.
Asked about prospects for water projects if California voters pass the Proposition 1 bond measure Nov. 4, Person said he believes “if a bond is ever going to happen, now is the time. If any are complacent about water storage and demand, a little drive past Shasta or Trinity right now gets you over it.”
He said raising Shasta Dam by 18.5 feet has been deemed feasible and would create storage for an additional 600,000 acre-feet of water though it would present some challenges, primarily involving Winnemem Wintu tribal lands in the McCloud River arm.
Asked about prospects for raising Trinity Dam, Person said there is zero discussion of that.
“Just look at the infill ratio and it points you to Shasta, not Trinity,” he said.
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