Records indicate major flooding has occured in Carson Valley about every seven years since the 1850s. Flooding could get worse if development alters the river's natural route, thereby decreasing the effectiveness of Carson Valley's natural flood plain, according to Ed James, spokesman for the Carson River Subconservancy District.
"The best way to protect the flood plain is not to build on it," he said. "If we can get all the counties working together and limit growth in that area, we can save a lot."
He spoke to the Douglas County Planning Commission on Nov. 13 concerning a plan for regional flood plain management along the Carson River watershed, a cooperative effort that includes Douglas, Carson City, Lyon and Churchill counties.
Flood damage comes with a price and that price was significantly higher in Washoe County, where the Truckee River was constricted by development after the 1997 flood, James said.
He estimated the cost of Washoe County damages for the 1997 flood at between $600 million and $900 million, well above the money spent in Carson Valley.
Douglas County's totals were between $6 million and $7 million, significantly higher than Carson City where limited development straddles the river. Costs dropped even lower in Lyon and Churchill counties, where there is even less development.
Plans to improve Washoe County's natural flood plain, reduce flooding, and restore the Truckee River's ecosystem are expected to cost $800 million.
Those are assets Carson Valley still has, but elevated roads, housing pads, and bridges change the natural flooding routes in the system, decreasing the natural flood plain function, James said.
"If we try to control our flood plain, we'll be in the same situation as Washoe," he said. "If we keep developing along the (Carson) River, we could have to spend $1 billion in the future to get back what we have today."
Following a mid-century flood, the Army Corps of Engineers straightened part of the Carson River downstream from Cradlebaugh Bridge to move water through the Valley more quickly and reduce flooding, but the rapidly moving water caused more hydraulic damage, impacting habitat and the river's natural function, James said.
"The curves in the river are what Mother Nature intended. It slows the water, which helps recharge the aquifer," James said. "Habitat and the environment are all critical to maintaining a healthy flood plain."
Project coordinator Genie Azad said a "living river approach" enhances water quality and supply, as well as the environment in general.
"If we build out along the river, we might as well pave it," she said.
The proposed plan includes a number of recommendations, including restricting or prohibiting development in critical flood plain areas, designing bridges and roads to protect the flood plain and evaluation of existing bridges for safety and flow constraint. The plan encourages conservation easements as well as transfer development rights programs to preserve open land along the river.
The best way to protect Carson Valley's flood plain is promotion and protection of the agricultural community. The Carson Valley acts like a sponge when it comes to water and preservation of this land is a great way to recharge local aquifers, James said.
"The (Carson) River wants to move constantly and due to earthquake formations, it's moving west," he said. "We have to deal with Mother Nature and it doesn't make sense to move development by the river when we know the bank will change.
"If we reinforce the banks to protect homes, we could end up like the Los Angeles River, " he said. "We have the opportunity to be different here."
A draft of the Regional Floodplain Management Plan should be completed by January. Community workshops will be scheduled for February and March 2008. The proposal must be approved by both planning and county commissioners in all the counties before it is submitted to the Federal Emergency Management Act in September.
Susie Vasquez can be reached at svasquez@recordcourier.com or 782-5121, ext. 211.
