‘With this new plan, the reservoir is expected to fill up maybe three out of every 10 years’ — Scott Roush

Proposed reallocation pool -- Graphic/USACE
Chatfield Reservoir proposed reallocation pool — Graphic/USACE

From The Denver Post (Scott Willoughby):

Attempting to separate Chatfield Reservoir and Chatfield State Park is a bit like splitting conjoined twins. There is significant risk, potential reward and inevitable growing pain. Yet that’s essentially what the proposed Chatfield Reservoir Storage Reallocation does. The plan to double water storage in the reservoir from its current recreational pool size will significantly alter the identity of the popular park that relies upon it.

The comment period on the project’s Final Environmental Impact Study closed at the beginning of September, and if the recommended alternative for reallocation is approved, neither Chatfield will ever be the same.

“It’s going to change the way the park operates if it goes through,” Chatfield State Park manager Scott Roush said. “The way we operate now, we know the water that Denver has is going to be there when we fill the reservoir back up in the spring. With this new plan, the reservoir is expected to fill up maybe three out of every 10 years. That makes it hard on the recreational side.”

Constructed on the South Platte just south of Denver in 1975, Chatfield Reservoir was built for both flood control and recreation. The 1,423-acre reservoir and encompassing 3,768 acres of land are owned by the U.S. Army Corps of Engineers and leased to Colorado Parks and Wildlife in 25-year cycles currently running through 2028. The park originally opened in 1979, the same year the state arranged an agreement with Denver Water granting storage rights in the reservoir with the understanding that, in general, it would be operated to allow for 20,000 acre-feet of storage (5,427-foot elevation) every summer for recreational purposes. From Memorial Day to Labor Day, Chatfield typically fluctuates no more than 5 feet. According to Roush, 2013 marked the first summer since 1979 that the pool dipped below the baseline elevation of 5,423 feet.

“That’s a pretty good track record,” Roush said. “We’re trying to maintain the water in the reservoir at a reasonable level for recreation like we’ve been able to do in the past. Visitors that come to Chatfield, that’s what they’re used to.”

Consensus holds that will no longer be the case should the reallocation proposal preferred by the Corps of Engineers be approved by federal and state officials as soon as January 2014. That plan to allow up to 20,600 additional acre-feet of storage for a conglomeration of municipal, industrial and agricultural water providers would raise the reservoir 12 vertical feet.

But the Corps’ own analysis recognizes that the junior water rights of the reallocation mean filling the pool to the new operating elevation of 5,444 feet will be inconsistent at best. And the absence of an operating agreement akin to the 1979 contract leaves park managers to deal with potentially frequent water fluctuations of 17 feet or more, affecting recreational users in a number of ways.

Filling the reservoir to the new level will flood 587 additional acres. Roads, parking lots, beaches, bike paths, trails, boat ramps, picnic shelters, fishing ponds and dog parks will be inundated. Restrooms and other buildings will be relocated to more than 600 horizontal feet above the low water line. Many relocated facilities will be constructed within the 10-year floodplain in order to provide reasonable access to the reservoir.

In a recent report to the state Parks and Wildlife Commission, Roush cited an increase in boating hazards along the reservoir’s shallow southern edge, shoreline mudflats exposed in dry years, loss of existing wetlands and new weed proliferation because of more frequent and greater water level fluctuations. Increased bank erosion is anticipated along with the loss of 0.7 upstream miles of the South Platte and wildlife habitat as up to 285 acres of trees will be removed.

Increased water fluctuation may disrupt spawning and recruitment of the lake’s wild smallmouth bass, CPW senior aquatic biologist Ken Kehmeier said. Similarly vacillating water levels are associated with elevated mercury levels in walleye at other reservoirs. Kehmeier says the proposal is likely to result in an additional 70 “zero flow” days per year in the South Platte below the Chatfield dam.

“We’ve been in discussion with the participants for the last year to try to put together a plan that would, if not mitigate, then minimize impacts. The toughest ones, obviously, have been park infrastructure and taking care of the park itself. And then the downstream issues,” Kehmeier said. “Because they’re such junior rights, there’s going to be a lot of years that they’re not going to have any water to release.”

Officials estimate a three-year construction period to restore services and implement proposed environmental mitigation in the park that annually attracts more than 1.5 million visitors and generates $2.2 million for the economically strapped state park division.

Not everyone believes the park’s current natural aesthetic can be re-established, however. “The quality of the recreational experience will be vastly different,” said Gene Reetz, a retired EPA employee and volunteer with SaveChatfield.org. “A lot of people think it will be just like it is now, only with higher water level. But most of the time it won’t be like that. It would be pretty devastating, not just to recreation, but to wildlife as well.”

Project proponents such as Rick McCloud with Centennial Water and Sanitation District maintain that even a changed Chatfield will remain a superb recreation and wildlife area. Others are skeptical. “I’m concerned as a manager about how successful the mitigation will be,” Roush said. “Is it going to be successful enough to maintain what you have today?”

More Chatfield Reservoir coverage here and here.

Drought news: Vail area remains in moderate drought #COdrought

US Drought Monitor Map September 17, 2013
US Drought Monitor Map September 17, 2013

From the Vail Daily (Scott N. Miller):

The Colorado Climate Center, the National Integrated Drought Information System and other agencies hold regular conference calls to determine what the next regional drought map should look like. As you’d expect, the flood-drenched areas of the Front Range have been removed from any drought designation. Most of the Western Slope, though, remains in “moderate” drought, despite the fact that the Water Center at Colorado Mesa University reports most of the region received at least 150 percent of its usual rainfall between Aug. 18 and Sept. 16…

State climatologist Nolan Doesken said the western part of the state has had enough rain to relieve “vegetative water” issues — keeping everything green. Streamflow is another matter.

“We still have the impacts of long-term dryness,” Doesken said. That dryness means streamflows, which are still suffering a kind of hangover from 2012. Doesken said the snowfall we received in April and May helped bolster stream levels, but the ground on the mountainsides was so dry from the drought that much of the late-season snow soaked in before it could run off into streams.

While streamflows have stayed below normal this season, the massive rainfall on the northern Front Range has helped the Colorado River going into the fall, according to a report from Hannah Holm, coordinator of the Water Center at Colorado Mesa University. The Colorado is tapped for Front Range use, mostly from high-elevation reservoirs in Summit and Grand counties. Since there’s no real need for Western Slope water right now, reservoir levels and Colorado River streamflows will be healthier than usual this fall.

That will help the river going into the next “water year,” which starts Oct. 1. And, Doesken said, September rains have helped build ground moisture going into this next year…

Doesken said that Klaus Wolter, a researcher at the Cooperative Institute for Research in Environmental Sciences at the University of Colorado at Boulder, has a more clear estimate for the fall. In the last drought report conference call Doesken said Wolter showed “distinct optimism” that the state could have a nearly-average fall season.

“Everyone (on the call) really breathed a sigh of relief when we heard that,” Doesken said. “It would really be nice to have a year that’s near average.”

‘Utter devastation throughout the floodplain…Whatever was in its path’ — John Batka #COflood

Barker Meadows Dam construction
Barker Meadows Dam construction

From The Denver Post (David Olinger):

Colorado is undertaking the largest emergency dam inspection program in state history, seeking to check 200 dams in 10 days, mostly along the South Platte River and its tributaries. All of Colorado’s high-hazard dams, which likely would kill people if they fail, withstood the recent record rainfall. But nine low-risk dams have breached, and an uncounted number of small ponds overflowed, contributing to the flood. Twenty other dams can be reached only by helicopter because roads below them washed out.

At least 55 engineers have offered to help the state dam safety branch with the inspections, and the agency has called all of its engineers in western Colorado to Denver.

In two days, “we had to write up the plan for what we wanted these engineers to do,” dam safety chief Bill McCormick said. “They’ll help do a workload that would have taken us six months.”

The inspectors will be looking for problems like increased seepage from large earthen dams, damaged spillways and clogged drainage outlets. Some small lakes and reservoirs might have to be drained for repairs.

McCormick, his deputy Scott Cuthbertson and John Batka, a safety engineer for dams along the St. Vrain and Big Thompson river systems, set out Thursday afternoon to see some of the known damage to the dams.

In Boulder County, at Pella Ponds Park, a trail system winds past a trio of ponds and lakes beloved by anglers and birdwatchers. The flood breached two, and their waters are pouring out. The parking lot is a cavernous hole, tipping over an outhouse at the edge. The trail, now a bumpy mix of gravel, stones, driftwood and landscape fabric, ends abruptly at a 10-foot-high cliff. The nearby St. Vrain River demolished this park.

“Utter devastation throughout the floodplain,” Batka said. “Whatever was in its path.”

Upstream, the river jumped its banks and formed new channels. The deluge filled McCall Lake, a high-hazard reservoir saved by its spillway.

At Left Hand Valley Reservoir, two spillways sent water over the edge. One, a staircase of concrete, survived with little apparent damage. The other, which doubled as the road to the reservoir, was destroyed. A 3-foot emergency berm now blocks the base of the access road. Above it, floodwaters carved giant gullies all the way to bedrock. It is among 70 reservoirs whose waters roared down spillways, some for the first time since they were built.

“This is a generational event,” Cuthbertson said, surveying the wreckage.

The dam safety program already took emergency action at 14 locations. One was Gaynor Lake, a Boulder County open space reservoir near houses and roads. When the lake filled, emergency workers brought in a backhoe to clear out clogged outlet ditches, leaving behind a mess of equipment tracks and a urine-like stench emanating from piles of dead cattails. Its embankment is temporarily braced with sand and gravel. McCormick watched the lake draining away for dam repairs. “We saw this as a serious condition,” he said.

He said Colorado residents can be thankful that its most hazardous dams met strict engineering standards and that grants from the Federal Emergency Management Agency’s national dam safety program helped train engineers and dam owners for this crisis. He said he hopes that a massive dam inspection program will find any hidden dangers — and reassure the worried people who call his office daily to report potential dam failures.

One came from a personal acquaintance who lives near the Button Rock reservoir in Larimer County. “Everyone in this neighborhood is on edge,” she told him.

From CBS Denver:

Record flooding continues in western and central Nebraska as the water that inundated Colorado flows east, but it appeared to cause few major problems because communities were able to prepare.

The National Weather Service says the South Platte River rose to 14.2 feet in North Platte to set a new record on Sunday. The previous record level of 14 feet was set in June 1935. The river also set a record in Brady at 9.85 feet Sunday — eclipsing the previous mark of 9.6 feet. Records were already set upstream in Roscoe, Neb., and Julesburg, Colo., late last week.

Here’s the link to the Longmont Times-Call ‘Colorado Flood’ section. Here’s an excerpt:

“I knew a dam had breached above Lyons, so the cops and I thought there was a wall of water headed our way. I remember being kind of freaked out.” [Gary Lindstrom] said he was relieved when the roadblock was moved east on 66 to 53rd Street.

Here’s a photo gallery from The Atlantic (Alan Taylor).