Auburn Dam Council Comments
The U.S. Army Corps of Engineers has developed three plans to increase the level of flood protection for Sacramento residents from the current 100-year level.
THE FOLSOM MODIFICATION PLAN
calls for the permanent “reoperation” (draining) of Folsom Reservoir each winter to make room for seasonal flood flows, improvements to Folsom Dam, and the 36 miles of downstream levees. This plan would provide Sacramento with 180-year level flood protection (a 1 in 180 chance in any one year of flooding). This plan includes lowering the dam spillway and increasing release capacity of dam river outlets, implementing an advanced warning flood plain evacuation plan, and improving 24 miles of downstream levees. The Folsom Modified alternative offers the lowest level of flood protection of the three plans, Sacramento could expect the highest average annual equivalent flood damages: $90 million.
ADC comments on the FOLSOM MODIFICATION PLAN:
Despite the planned improvements to Folsom Dam, there still a 46% chance of system breech and failure should a 200-year storm event strike Sacramento. For this reason, this plan fails to meet the minimum flood protection standard for Sacramento set by the non-federal cost sharing partners, the State of California and the Sacramento Area Flood Control Agency (SAFCA).
The Folsom Modification Plan would permanently increase the flood control space at Folsom Reservoir negatively impacting water supply and power generation according to the U.S. Army Corps of Engineers. The Corps has calculated this impact over the 100-year life of the project at $114 million. We feel that more threatening to the region is the lack of dependable water supplies from Folsom Lake given recent and extended drought periods in California. Winter storms and spring runoff cannot always be counted upon to refill the reservoir after Folsom has been drawn down every winter.
FOLSOM STEPPED RELEASE PLAN
is similar to the Folsom Modification plan. It would add extensive modifications to 36 miles of American River levees, Sacramento Weir and Bypass, and Yolo Bypass levees to permit elevated releases from Folsom Dam of up to 180,000 cubic feet per second (cfs)-a 56% increase over the current capacity of these levees. The Stepped Release alternative would provide a 235-year level of flood protection for Sacramento (1 in 235 chance of flooding in any one year) and have a 32% chance of breach in the event of a 200-year storm. This plan does not meet the minimum flood protection standards for Sacramento. Average annual equivalent flood damage has been calculated at $80 million.
ADC Comments on the FOLSOM STEPPED RELEASE PLAN:
The first and last defense under the Folsom Modified and Folsom Stepped Release Plan would be levees. According to a recent Sacramento Bee Article “Budget cuts and environmental regulations have compromised repairs of 1600 miles of state-controlled levees that are part of the Sacramento and San Joanquin flood-control projects”. State leaders and lawmakers have also cut the flood management budget of the Department of Water Resources by 74%, from $116 to $30 million. DWR now admits it can’t meet many of its flood-control obligations, which include maintenance of essential flood channels, such as the Yolo Bypass that shunts water around Sacramento. According to the Bee, “some of these erosion sites increase the flood threat to such heavily populated areas as downtown Sacramento, the Pocket-in south Sacramento-and Natomas, to the North.”
Are we being pennywise and pound foolish?
Besides environmental concerns, much has been made about the cost of the proposed flood control projects. But are we being pennywise and pound foolish considering the potential damage to over 400,000 lives and $20 billion dollars in property? It would seem that if we do not pay now, we’ll pay later. In 2002, the 6 th Appellate District of California found that Monterey County and three other counties were responsible for the damage from a 1995 flood that overwhelmed levees on the Pajaro River, near Watsonville. The 3 rd Distrct Court of Appeals found the state liable for the 1986 levee break in Yuba County. These rulings may very well set the precedent that could place California risk of facing billions of dollars in liabilities. We can either choose to continue paying those damages or invest in a flood control system that will provide both flood protection and water supply.
would provide Sacramento with an extremely high 500-year level of protection in accordance with federal guidelines. The chance that a 200-year flood event would overwhelm the dam and levee improvements is a minuscule 3%. The dam would provide a level of protection that would no longer require flood insurance.
Although the most expensive of the three plans, the dam alternative provides 1.5 times greater net average annual flood control benefits than the other two plans, together with a benefit to cost ratio of 1.8 to 1. A 1991 report developed for Congress stated, “For highly urbanized areas such as Sacramento, a flood detention facility is preferred over levees. Reliance on levees for flood protection is inherently less safe than an upstream detention dam.”
The Detention Dam plan would increase water storage over the current Folsom Reservoir reoperation plan. The potential exists for joint flood operation of Folsom and the flood control dam at Auburn, adding to the region’s available water and power supply. The Corps has calculated this increase in water, power, and recreation at Folsom to be $2.6 millin each year or $58.5 million over the life of reoperation.
ADC comments on the DETENTION DAM
The flood control dam significantly increases flood protection reliability because 894,000 acre-feet of water will be removed from flood flows reaching Sacramento. Even flows greather than a 500-year flood will be significantly reduced, thereby reducing the threats to life and property.
The Dentention Dam plan would allow the discontinuation of the Folsom Reoperation Plan. This would allow for higher Folsom Reservoir levels which could benefit downstream fisheries. Higher lake levels at Folsom Reservoir would enhance the beauty of the lake and its recreational experience.