Reno Gazette-Journal from Reno, Nevada • Page 13

Today's Topic: Flood Of 1 997 Saturday, September 20, 1997 Reno Gazette-Journal 13A Hold on: This year's disaster wasn't the Big One Not 1 0O-year category: Means not as prepared as it thought it was. The USGS, the keeper of the nation's stream-flow records, says the 1997 Truckee River flood was a less than 50-year event; the Corps, which builds flood control projects, says it was a 60-year event; FEMA, which sets the rates for flood insurance, says it was a 75-year event. All the agencies are expected to meet over their calculators in the coming months to try to come up with one number they can all live with. "The communities are interested in getting the right answer. They don't want a specific answer," Forest said.

"Are they regulating to the level they should be, or does this event suggest something? "We need to be able to explain that answer and to defend that answer to the public, because the implications to businesses are extremely critical." "We know these estimates are just that, estimates," Forest said. "But they're within a range, and the more records you have the shorter the range of probable values. "We do the best we can, and what we're trying to do is identify the level of risk by trying to come up with a reasonable estimate of what the flood discharge frequency is for a stream and try to limit development in areas that are at risk." Not even the engineers agree on what constitutes a 100-year flood along the Truckee River. The USGS, the U.S. Army Corps of Engineers, and the Federal Emergency Management Agency each have numbers.

Forest is doing an analysis of all the numbers and will present his numbers and a report to local governments in the next week or so. California, Davis. "It's a statistical best guess based on a skimpy historical database. "The errors are huge in all of this. We do this because we need a number.

We need something hard, and floods don't work that way." The database for flood statistics is so small that every time a large flood comes along it has an overwhelming influence on the statistics themselves, Mount said. When flood events are plotted out on a graph, the latest big flood tends to steepen the curve and set a new standard for the 100-year flood flow. "What was a 100-year event on Jan. 1 may become as small as a 50-year flood the following year," Mount said. Forest is not so pessimistic, although he agrees that a longer period of record helps engineers come up with a better estimate for the flood plain.

elsewhere." Delineating the area covered in a 100-year flood isn't easy. Forces that affect flooding are complex and keep changing over time. Rivers constantly change their channels as they move tons of rock and sediment around. Development along rivers also affects flooding because it speeds up and contributes runoff and displaces flood waters, making the flood plain even larger. Then add the short period of recorded weather and stream-flow information.

The Truckee River has only about 100 years of records for scientists to look at. Climate oscillates over time, and it's hard to know if a region is on the wet side of the climate cycle or the dry side. "We're locked into the silly notion that a 100-year flood is meaningful, and it is not," said Jeff Mount, chairman of the geology department at the University of 100-year flood as it thought it was. Buildings once thought to have been built above the 100-year flood mark were flooded in January. "The implication is pretty substantial for the industrial area," said Mark Forest, an engineering consultant hired by the cities of Reno and Sparks and Washoe County to double-check the USGS' findings.

"Should the flood plain be increased, those that have properties that were built above the original flood-plain elevation would end up paying a considerable amount of money in flood insurance. "Knowing that, many of the tenants in the industrial area would choose to relocate their businesses I fit I ft Months later, bridge replacement begins By Faith Bremner RENO GAZETTE-JOURNAL The Truckee River flood of 1997 was big but it wasn't the Big One, a report released Friday by the U.S. Geological Survey says. After months of flagging high water marks, surveying the river channel and running numbers through computer models, USGS engineers say January's flood along the Truckee was less than a 50-year flood. That means many Truckee Meadows residents can expect to see an even bigger flood during their lifetimes.

It also means the community isn't as prepared for the inevitable Corps seeking $101 million in control efforts By Faith Bremner RENO GAZETTE-JOURNAL The federal government has come up with a plan to stop 100-year floods from inundating the Sparks industrial area and east Reno. But it would require miles of new earthen levies and concrete flood walls along the Truckee River. The U.S. Army Corps of Engineers' Truckee Meadows Flood Control Reconnaissance Report is recommending $101 million worth of flood-control projects along the Truckee River and its tributaries between U.S. 395 and Vista.

The goal is to have the Truckee carry 26,000 cubic feet of water per second slightly above the new calculated 100-year flood flow without inundating the Sparks industrial area and RenoTahoe International Airport. The plan also calls for more bike and pedestrian paths, observation decks and picnic sites. A portion of the University of Nevada, Renews experimental farm on ill Street would be turned into a flood-detentidfl pond. "We neeoto get together with the environrrie'ntaHsts and people in the industrial area and decide how much protection we need and want and how much aesthetics we are willing to give up," Sparks Emergency Management Coordinator Mike Steele said. "We don't want to make the river a trench.

"Plowing under the Truckee Meadows and returning it to nature isn't a reality, either." David B. ParkerReno Gazette-Journal file SOGGY DOWNTOWN RENO: A youth crosses flooded First Street during the flooding in January. negotiate with the bankruptcy court to have the work done. The bridge is a hazard to river users and people downstream, Albright said. The bridge could move during high water and pieces of it are already two miles downstream, he said.

The river current tries to push boaters into the bridge, he said. "A rafter could get swept underneath and get pinned," Albright said. "The well-versed kayakers can see the danger, but a typical inner tuber or river runner is potentially going to get snuffed." The bridge was designed to withstand a 100-year flood. However, federal flood experts are leaning towards calling the January flood a 50-year flood. There's nothing the city can do to require Trandec to make the new bridge withstand even higher flood flows, said Bob Gottsacker, principal engineer for the Reno Community Development Department.

Once the subdivision is completed, the developer will turn the bridge and the responsibility for maintaining it over to Washoe County, Gottsacker said. "The bridge is being built according to the regulatory flows that are in place," Gottsacker said. "Until those are changed, I know of no means to force them to do more." A Bailey bridge is an inexpensive, strong, lightweight metal bridge that's easy to transport and bolt together. The British military came up with the design in World War II. By Faith Bremner RENO GAZETTE-JOURNAL Eight months after the New Year's flood tossed it like a tinker toy, a crumpled metal bridge in the Truckee River is finally being removed and replaced.

Just this week, a contractor working for a west Reno developer went into the river to begin dismantling the broken bridge and putting up a new one. The city of Reno required Trandec Inc. to erect the narrow metal truss bridge, called a Bailey bridge, as a condition for building the River Park Subdivision. The bridge served as secondary, emergency access for the subdivision on the south side of the Truckee across from Mayberry Park. The city won't allow the current builder in the subdivision, Lakcmont Homes, to sell more houses until the bridge is replaced.

The subdivision will eventually have 240 homes. Seventy-two have already been built. "Considering that Lakemont won't get any (certificates of occupancy) until the bridge is back, the motivation to get the bridge back up is definitely there," said Dan Cantrell, a quality assurance inspector for the city of Reno. "Hopefully this winter it will be back up, but we have no control over the timeline." Local kayaker, Charles Albright, began bugging the city to remove the bridge right after it went down. However, Trandec was in bankruptcy, and it took the city a while to The Corps came up with a similar plan 1 0 years ago but put it on a shelf because it was deemed too expensive.

For every 1 the Corps invests in a project, it expects to protect at least 1 worth of property. But the $540 million in property damage from the January flood convinced the Corps the project would be economically worthwhile. The January flood also showed that some areas of the Truckee Meadows are more susceptible to flooding than previously thought. The Corps is calling the January flood a 60-year flood while the U.S. Geological Survey says it was less than a 50-year event.

The cost for building flood walls, levies and detention ponds would be split bet ween local governments and the federal government. The local share would be either 25 percent or 35 percent, dependingon whether federal officials decide the Champion, a machinist by trade. "If you're cocky enough to think it won't flood where you are, it will come and spank you." But buying out all of the homes and businesses along the Truckee's flood plain is not an option, said Donna Garcia, a study manager in the Corps' Sacramento office. More than 6,000 structures and $3 billion worth of property are in the flood plain. A building moratorium in the flood plain is equally impractical, said Mark Forest, a consulting engineer who works for the cities and the county.

"That's called inverse condemnation, and that requires a public agency to purchase the property," Forest said. "You can't tell somebody they can't develop. "All you can do is put reasonable restrictions on them to protect the health of the public." project falls under the 1988 water resources development act or the 1996 act. But John Champion, who plants trees and traps beavers along the Truckee in his spare time, said it's futile to try to control floods. Champion has seen five big floods along the Truckee in his 53 years of living in Reno.

"This whole thing is a giant effort to keep people busy," Champion said of the Corps' flood-control plan. "We've overbuilt the area, and you cannot keep these people dry anymore." Champion advocates giving the river room to move and stopping development in the flood plain. Humansareonlyfoolingthemselves if they think they can make the river do what they want it to do, he said. "The river doesn't have any choice. It's just water going downhill through a bunch of geology," said Flood During the January flood, the water master had to release 2,500 cubic feet per second from Tahoe to keep the lake below the court-set maximum storage limit.

That release made up about 14 percent of the total flood flows through downtown Reno. That water could have been stored in Lake Tahoe had there been only 2 'inches of storage space, the report says. There is one flood control measure that could help downtown Reno that would cost nothing revising the rules for storing water in Lake Tahoe. Instead of filling Tahoe to the maximum legal limit and then releasing water, the federal water master could release water sooner and leave more room for flood waters, the plan says. protection and improve flood capacity," Daily said.

In its Truckee Meadows Flood Control Reconnaissance Report, the Corps looked at building flood-walls along the Truckee through Reno, replacing the bridges and knocking down the concrete channel through downtown and terracing back the banks. However, the Corps determined the costs outweighed the benefits. The city asked the Corps to come up with a less costly plan that would protect downtown from a 50-year flood or a 75-year flood, Daily said. The U.S. Geological Survey estimates the January flood was less than a 50-year flood.

"We think somewhere in there is a project that will still benefit downtown that ill have a more favorable cost-to-bencfit picture," Daily said. city's engineering department, said whatever is built at the site will have flood-proofing features, like high entryways and special doors and emergency gatesthatkeepout water. A portion of the site could even be terraced back to give the Truckee a little more room to move. "There may be an opportunity to combine some of this work in a public-private effort to redevelop the riverfront blocks, improve flood From 1A rants on two river-front blocks in downtown Reno. During the January flood, the Truckee iver flooded over the same site.

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