The New Year’s Eve Flood sparks debate on what we learned from the Flood of 1997 and whether the new flood project is putting our resources in the right places
Those who want a better understanding of Reno’s periodic floods don’t have to go to the periodic meetings of the Flood Project Coordinating Committee down in the Washoe County Commission chambers. They don’t have to get a degree in civic or hydro engineering from the University of Nevada, Reno—although that wouldn’t hurt. They don’t even need to get in a helicopter during a flood to see how far the water spilled over the banks and how many homes and businesses got washed out.
All a person needs is to take a walk downtown along the river with Jerry Purdy.
Purdy is one of the many critics who turn out when the area’s flood planners have public meetings. His fundamental questions are these: How can the cities and county claim to be working on flood control when they haven’t done the common sense, relatively inexpensive things that will decrease floods? How can they consider raising sales taxes when they haven’t spent the flood control money they got for flood control? (See sidebar story.)
The answer, or at least part of the answer, will probably surprise people like no-nonsense Purdy.
The pen is mightier than the flood
Purdy, 72, was employed by the Federal Highway Administration starting in the ‘50s, sometimes working floods. He moved to Nevada in 1960 and left the feds in the ‘80s, so he didn’t have to move east. Later, he worked as a flood consultant for the Federal Emergency Management Agency.
Originally out of Wyoming, the retired civil engineer exudes a kind of Western sincerity. He uses simple grammar and charming colloquialisms. He wears a brown leather flight jacket, a green bush-style shirt, tan pants and sensible shoes. Although he’d probably deny the comparison, his vibe is similar to the cowboy humorist Will Rogers. He’s got sandy gray hair, and after a hike, he walks with a limp because of hip-replacement surgery.
To hear Purdy tell it, you’d think all of hydrology, at least from a flood reference, could be boiled down to two equations.
The first: River flow equals cross-section diameter times water velocity. Yes, it’s math, but it’s simple—water flows faster through a bigger pipe. The formula results in amounts that are measured in cubic feet per second.
If you want to decrease flooding in the Truckee Meadows, like that of the New Year’s Eve Flood, says Purdy, you need as clear a river channel as possible to get that water to the other side of Sparks as quickly as possible. You also have to decrease the amount of water that goes into the river.
To do that, Purdy says laws must be passed to close gates at upstream sources and reservoirs—Martis Reservoir, Prosser Dam, Boca Reservoir, Lake Tahoe—when Reno-Sparks is threatened by flooding.
“This is stroke-of-the-pen flood control,” he says. “Doesn’t cost you a thing. It’s the very first thing you do, and then you don’t have to spend $100 million on some little, dinky detention basin.”
To be fair, the floodgates were handled much better during the New Year’s Eve Flood than in the Flood of 1997. Only about 44 percent of the overbank water came from upstream reservoirs. And to stop the flow out of Donner Lake, which proved some 400 cubic feet per second, a dam would have to be built—not likely to happen.
That “little, dinky detention basin” leads us to the second formula: 1 cubic foot per second of flow is equal to 2 acre feet per day.
“A guy oughta staple that on his T-shirt,” Purdy says. “One cubic foot per second will cover two acres with a foot of water. That’s all. Nothing more to it.”
This formula shows the impotence of buying property for flood-water storage. Let Purdy do the math: “We’re going to build a 600-acre detention basin out here at University Farms, and we’re going to dump 20,000 cubic feet per second into it. How long is it going to take to fill an acre if you dump 20,000 cubic feet per second into an acre, [which is] 43,000 square feet? Two seconds. Two seconds, you’ve covered an acre a foot deep. We’re talking 600 acres times two seconds per acre. That’s 1,200 seconds. There’s 60 seconds in a minute; that’s 20 minutes to fill it up.
“Let’s say, ‘Goddammit, we’re going to have that three feet deep; so 20 minutes times three. That’s one hour to fill up the entire thing.”
Purdy says a large percentage of the water that went over the Truckee’s banks and flooded Reno and Sparks at the beginning of the year could have been stopped if the gates at the upstream reservoirs had been closed. He says one other no-brainer that could’ve decreased damage in the Truckee Meadows during high waters has been virtually ignored by local flood planners: The Army Corps of Engineers has repeated in study after study, for more than half a century, that sediment should be removed from the riverbed.
Go back to that first formula. The more sediment there is in the river, the less water can flow through, and the more goes over the banks and drowns homes and businesses. Take a peek at the new whitewater park. Thousands of cubic yards of collected silt were removed, and the water is fast. Now walk over to the Center Street bridge. Look east. See all those sandbars along the sides, those islands? None of them are supposed to be there, not if you want less flooding.
It’s difficult to calculate on the fly how much it would cost to remove the sediment, and it’s not a one-time deal. If it were done once, a regular, probably annual, system of removing debris would have to be set up. According to the 1985 study by the Army Corps of Engineers, the river deposits some 51,300 cubic yards (61,400 tons) of sediment annually near the Truckee Meadows. After the Flood of ‘97, the city of Sparks—led by Michael Steele, senior administrative analyst and emergency management coordinator, and the National Resources Conservation Service—removed 23,400 cubic yards of gravel and debris from between Glendale and Vista. That cost $300,000. At the time, Steele said if Reno and Washoe didn’t clean out their parts of the channel, Sparks’ efforts would have little impact. (As point of fact, Sparks is again working on a flood project, the relocation of the North Truckee Drain, outside of the flood project master plan.)
Steele is now city manager of Burnet, a small city in central Texas. A friend mailed him pictures of the New Year’s Eve Flood; he wasn’t surprised that Sparks bore the brunt of the damage. He repeats that, unless all three entities take care of their responsibilities, Sparks is always going to get the worst of it—the river channel is shallower there.
“And where’s the receptor of all that stuff during the next flood?” he asks. “Sparks again. And that’s how we got hammered last time; it all flows downstream. We [removed the sediment] because we felt it was a necessity to prevent further damage next time. You either raise the bridges or lower the river, and we just lowered the bottom of the river so that it could carry more.”
Still, a million bucks a year to remove sediment and debris from the river seems like a drop in the bucket compared to the $350 million project (and an additional one-eighth-cent sales tax hike) that the Flood Project Coordinating Committee is looking at with the Army Corps of Engineers.
Few would argue that the prophylactic benefits wouldn’t be almost immediate. But, as crazy as it sounds, any improvement in the flood situation may actually drown Northern Nevada’s chances for fixing the flood problem once and for all.
Bridge over troubled waters
Jerry Purdy is joined by any number of knowledgeable folks who’d like to offer skills and ideas to the Flood Project Coordinating Committee. Many got hit by this last flood or have certain expertise that isn’t represented on the committee, and they surface for public comment when the committee meets.
One such is Gary Norris. He’s been a professor of civil engineering at the University of Nevada, Reno for some 23 years. He belongs to more associations than you could shake a divining rod at and has had leadership roles in many civil engineering groups, including the American Society of Civil Engineers.
He’s a specialist in soil, and he’s particularly interested in the soil beneath the downtown bridges. He subscribes to the Jerry Purdy school of flood prevention—increase the size of the channel, and you will have fewer floods. Of course, he has his own twist. He wants to see new engineering methods applied to Virginia, Sierra and Lake street bridges to anchor the bridges better, so more sediment could be removed from beneath. He calls the technology “micropiles.” The micropiles are essentially nails that go through existing piers into more solid firmament. He says it’s an inexpensive fix that can increase the flow under the bridge and prevent “scour"—water erosion—from undermining the bridges. And that works whether the bridge is replaced or just repaired.
Norris has other ideas as well. An associate from Canada recommended Reno look at something called “geotubes,” which are basically long, collapsible tubes that can be filled with water (even flood water) and used as temporary flood walls. The key is to do something, preferably before another flood comes.
“This is similar to the street problem we had many years ago when we didn’t seal the cracks,” he says. “We ended up spending a heck of a lot more when all the roadways failed, and we had to tear them up and redo them. Maintenance. You can pay it now or pay it later, but it’s much more distressing reconstruction later in terms of the effect on traffic and the like.”
Dammed if you do, dammed if you don’t
With all due respect to those who’d offer expertise in flood management, there are folks like Naomi Duerr and Paul Urban who eat, drink and sleep Truckee Meadows floods. Urban has been flood project manager almost since the one-eighth cent sales tax for public safety and flood control went into effect in ‘98. Duerr, flood project director, has been with the group since July, although she’s been working floods for much of her career.
The pair is steering the agency that’s working with all the groups, including the Army Corps of Engineers, toward the final Truckee Meadows Flood Control Project. At a Jan. 13 meeting, Duerr broke the news that, due to the expectation of property purchases, including the University Farms and the Butler Ranch, the Project is between $42-192 million short, and it’s likely Washoe County will need to increase the one-eighth cent sales tax to one-quarter cent to pay for it.
Each believes the community handled the New Year’s Eve Flood better than the Flood of ‘97. Better technology for flood prediction and new gauging stations on the river helped. We had the flood-response plan, which was developed after ‘97. Because of better forecasting, sandbags were placed in a strategic area near the airport, and it wasn’t flooded.
Each admits there were ways the flood could have been handled better. Duerr says word should be given to at-risk property owners sooner, and there should be better procedures for sandbag stations and refined methods for telling the public the level of danger.
Duerr is the first person people usually go to when they have an idea that will save Reno and Sparks from flooding. Sometimes, it can be frustrating.
“These 10 people think this, these 50 people think something else, and these two, who are really smart engineer people, think something entirely different,” she says. “These people over here in Hidden Valley think the whole problem’s about them. The airport thinks it’s all about them. Reno thinks it’s all about them and could care less what’s happening over here. Some people think it’s very simple—we just have to dredge the river; we just have to blast the Vista Reach some more. I’m somewhat patient to listen to those people, but being a geologist, working with these kinds of projects, we are refashioning the entire hydrology here. And it’s not a simple thing of dig out a channel a few feet or clear some debris. That will lower water levels a little bit. But then, guess what, sediment will redeposit.
“I think the vision here was to go for the big things, go for something that’s going to really address the problem, not just be a Band Aid.”
It’s Urban, though, who has the real answer as to why the little common-sense flood-mitigation work hasn’t been done since the Flood of ‘97. It’s Urban who explains why so little of the one-eighth sales tax has been spent on smaller projects that decrease the height of flood waters. While he doesn’t believe sediment removal has much effect on the river, the real reason goes back to the Army Corps of Engineers’ methods of analysis:
“A lot of people have asked, ‘Why aren’t we building some levies or small parts of the project?’ And because we don’t have the $350 or $400 million in our pocket, and we’re asking the Corps for the money, the Corps … has this huge process where they go and study everything. And that’s what we started again in 1998 after the ‘97 flood. And they have still yet to come to a completion of their analysis.”
“If we would be building parts of what we think the flood project might look like, if we build something that actually provides protection to someplace, then now, we’ve lost the ability to count those benefits towards the project.
“Then we find ourselves where we are thinking we are helping ourselves by doing projects ahead of time, but we end up having a project that no longer is justified, according to Corps policy. Now a lot of this doesn’t make logical sense, but remember not much of what the Corps or the federal government does makes logical sense.”
Get it? If we improve things from a flood-mitigation standpoint, we stand a chance of losing the Army Corps of Engineers money and help. According to the ever stricter formula the Corps uses to perform its cost-benefit analysis, if things get even a little better, the Washoe County flood project may no longer pencil out. A levy can be repaired, or a riverbank can be repaired, as long as it doesn’t significantly decrease the amount of water that spills over the Truckee’s banks in a flood.
And that’s a harsh reality that guys like Jerry Purdy might have little truck with.
“One of the great Socrates in my time, in the flood-control game, said, ‘There’s room enough in the channel for water or gravel, but not both,'” Purdy recalls. “You start getting more gravel, there’s less room for water. So when the channel is full [of gravel] the water is going somewhere else.”
But that sort of thinking may be water under the bridge—at least until a final flood plan—the Community Coalition Plan, also known as the locally preferred plan—is presented to the Army Corps of Engineers and the Flood Project Coordinating Committee. And that may happen as early as next month.
RN&R intern Katie Palani contributed to this report.