Why the C-BT sullies the clarity of Grand Lake, and why it’s so hard to fix
by Allen Best
GRAND LAKE, Colo. — Nobody disputes that the Colorado-Big Thompson project has changed Grand Lake, the state’s largest, deepest natural lake. How could it not?
In the 1940s, Grand Lake was integrated into the giant C-BT, what the late historian David Lavender called a “massive violation of geography.” It’s Colorado’s largest transmountain diversion project. By one tally in the 1990s, it delivers an average 231,060 acre-feet annually from the headwaters of the Colorado River to cities and farms east of the Continental Divide. This compares to the 105,024 acre-feet from three tunnels through the Sawatch Range east of Aspen.
Almost immediately after the C-BT was completed in 1953, locals began to complain that the project shoehorned into the lake had sullied the lake’s clarity by introducing algae and sediments. This is, they insist, a violation of federal law.
The controversy pivots on Senate Document 80, a part of the Congressional authorization for project funding in 1937. The document describes the needs of irrigation, industrial and power production but also warns against impacts to nearby Rocky Mountain National Park.
The lake, if outside the park, has one of Colorado’s most memorable backdrops. The document specifies the need “to preserve the fishing and recreational facilities and the scenic attractions of Grand Lake…”
On that, say many locals, the C-BT has failed, and they say that until recently they got little response from the U.S. Bureau of Reclamation, the agency that built the C-BT.
But now, in a reversal, the bureau is working with 18 other stakeholders in an effort to solve the problem. Parties include Northern Colorado Water, the agency that manages the diversions for cities and farmers of northeastern Colorado, Grand County and other state and local organizations.
Grand Lake’s story fits into a broad theme of changed sensibilities in Colorado about 20th century river alterations. Restoration and remediation projects are starting or underway on the San Miguel River in Telluride, on the Eagle River at Camp Hale and on the Fraser River near Winter Park.
“It’s possible that at one time, the impacts of the CBT Project on Grand Lake clarity were thought to be just part of the price we pay for valuable water projects,” said Anne Castle, a fellow at the Getches-Wilkinson Center for Natural Resources, Energy and the Environment at the University of Colorado-Boulder. “Now, we are more inclined to believe that the environmental values have significance, including economic significance, and that operations can and should be adjusted to better accommodate these values.”
The work at Grand Lake also illustrates the power of persistence and spunk by advocates of environmental protection. And it involves a collaborative process called adaptive management that emphasizes consensus-based decision-making in solving stubborn issues involving water diversions.
The difficult problem
Nobody thinks solving this problem will be easy, though. In April, after several years of working together, the Grand Lake stakeholders submitted a plan to the Colorado Water Quality Control Commission. The plan approved by the commission sets an interim clarity goal for summer pumping during the next five years.
During that time, the Bureau of Reclamation is to develop a plan for long-term solutions. Alternatives include expensive new tunnels, possibly bypassing Grand Lake altogether. A preview of the alternatives may emerge at a meeting of stakeholders in late November.
Not everybody in Grand Lake thinks that reduced clarity is a problem. “There are people who think there’s a problem, but there is no problem,” says Jim Gasner, a member of the Grand Lake Board of Trustees, the town’s elected body, and a fishing “teacher” at Rocky Mountain Outfitters.
But Elwin Crabtree, a real estate agent and former Grand County commissioner, sees something different. “It’s adverse to its natural being,” he said in early August in an interview at his office along the town’s main street of knotty-pined stores and lodges. “I think we look at it as a moral issue,” he added. “I think we believe in having responsibility to be good stewards of our environment.”
The C-BT is an effort to address what one historian in the 1950s called “nature’s error.” Even as Aspen was putting on its silver-lined britches in the 1880s, farmers along the South Platte River and its tributaries were struggling with inadequate water in late summer to finish their corn and other crops.
Irrigators set out to remedy this. The first large-scale transmountain diversion from the headwaters of the Colorado River began in 1890. Called the Grand River Ditch, it’s beveled into the side of the Never Summer Range in what is now Rocky Mountain National Park, collecting water like a rain gutter from a roof.
Then came the 1930s, the decade of the Dust Bowl, the Great Depression and the New Deal. Farmers in northeastern Colorado had long been agitating for added infusions of water from the Colorado River headwaters. But they couldn’t get it done themselves. They needed federal funding.
The flawed design
But the work along the Continental Divide from 1939 to 1953 created a wound at Grand Lake. In retrospect, the design was flawed.
The C-BT at the Colorado River headwaters consists of three main bodies of interconnected water. Only one, Grand Lake, is natural.
Farthest downstream is Granby Reservoir, which is Colorado’s third largest, behind Blue Mesa, near Gunnison, and Navajo, on the New Mexico border, southea
st of Durango. Granby can hold 539,758 acre-feet of water during runoff of spring and early summer. This compares to Ruedi Reservoir’s 102,373 acre-feet and Dillon’s 257,304 acre-feet.
From Granby, water is pumped upstream as needed by Eastern Slope diverters to Shadow Mountain Reservoir. Shallow, no more than nine feet deep, Shadow Mountain is directly connected through a short canal to Grand Lake.
The canal occupies the original path of the Colorado River emerging from Grand Lake. From the interconnected Grand Lake and Shadow Mountain Reservoir, water is then pumped through the 13.1-mile Alva Adams Tunnel underneath the national park to the Estes Park area for storage in reservoirs there and along the northern Front Range.
Shadow Mountain is a problem, though. Its shallowness allows water to be easily warmed in summer, producing algae that can float into Grand Lake. The shallowness also allows lake-bottom sediments to be disturbed more easily and dispersed into Grand Lake.
Evidence for the historic, pre-construction clarity of Grand Lake is scant: Just one measurement, taken in 1941, of 9.2 meters (30 feet).
Detailed observations during the last decade show clarity down to 6 meters (19.6 feet), but no more.
The standard adopted in April by the state agency specifies a minimum of 2.5 meters and an average of 3.8 meters (8.2 feet to 12.4 feet) during summer diversion season.
“I think the clarity standard has really elevated the discussion,” says Lane Wyatt, co-director of the water quality/quantity committee in the Northwest Council of Governments. “This is the only clarity standard in Colorado. It’s the first one we’ve ever done.”
Clarity is not the only issue, though. Water must be delivered to farms and cities. As it flows downhill toward the Great Plains, it generates electricity distributed by the Western Area Power Authority. Purchasers of this low-cost power include Aspen Electric and Holy Cross Energy.
Canton “Scally” O’Donnell, president of the Three Lakes Watershed Association, remembers a more pristine past.
When he was a boy, his family summered at Grand Lake. That was in the 1930s and 1940s. “We drank the water right out of the lake, and many families did that,” O’Donnell said.
The first complaint about the sullied water was filed in 1954, the year after the project’s formal completion. In 1956, Grand Lake trustees adopted a resolution that informed Colorado’s congressional delegation of problems. The resolution was aimed at the Bureau of Reclamation.
“I think it’s fair to say that up until seven or eight years ago, the bureau pretty much stonewalled,” O’Donnell said. “They just did not want to recognize the problem, and Northern Colorado Water, the same.”
Movement has occurred during the last decade. One avenue for local protest was a proposed expansion of an existing diversion of the Colorado River at Windy Gap, about 15 miles downstream. Completed in 1985, the Windy Gap dam uses the C-BT infrastructure to deliver additional water to the Rawhide power plant north of Fort Collins, Greeley, Boulder and other cities.
The Windy Gap Firming, or expansion, plan was formally introduced after the drought of 2002. It proposes diversion of remaining water rights owned by a string of northern Front Range cities.
The effect of persistence
O’Donnell, of the Three Lakes Watershed Association, thinks the changed attitude is explained by the persistence of individual public officials. He singles out Lurline Underbrink Curran, then the Grand County manager. “She’s smart and she’s tough,” he said. “She just kept on beating on everybody to make it happen.”
He also points to the influence of Anne Castle, a long-time Denver water lawyer who served from 2009 to 20014 as assistant secretary for water and science in the Interior Department. Her responsibilities included oversight of the Bureau of Reclamation.
“I think part of the reason it has attention now is the fact that the Windy Gap Firming Project required the federal government to pay attention to Senate Document 80 and both C-BT and Windy Gap Firming Project do have an impact on Grand Lake’s recreation and scenic attraction. Calling attention to that issue, as both Lurline and I did, with prodding from Scally, had an impact,” Castle said.
But again, agreeing there is a problem is not the same thing as finding a solution.
“There is a lot of uncertainty about how our operations affect clarity,” said Victor Lee, an engineer for the Bureau of Reclamation.
The precise circumstances that cause algae and sediments to degrade clarity are poorly understood. Northern has been altering its diversion regimes, to see if that will improve clarity.
This year, from July until late August, pumping was conducted about 15 hours a day at 250 cubic feet per second. Clarity degraded, though. Algae growth was suspected. So the pumping was accelerated to about 20 hours a day with two pumps. Results were mixed.
It was a success, said Lee, in that they learned something. Clarity readings exceeded the minimum but did not meet the average standard. “I would say the experiment was successful, but we did not meet our objective,” he said.
Esther Vincent, water quality manager for Northern Water, said the effort to address Grand Lake’s muddled clarity is attracting attention across Colorado by water professionals. Spurring their interest, she said, is the possibility of other bodies of water being assigned clarity standards.
There’s also interest in the adaptive management process created for Grand Lake. It’s similar to but separate from Learning By Doing, which was created in response to expanded water diversions from both Windy Gap and by Denver Water’s Moffat Tunnel collection system.
Vincent also points out a deeply philosophical question. In 1937, when adopting S.D. 80, did Congress have the same notion about what constitutes “scenic attraction” as we do today?
“I am an engineer,” she said. “Asking an engineer to define what beauty is, is an interesting dilemma. It’s not a concept that lends itself very well to science.”
This story was funded by Aspen Journalism and originally published in the Aspen Daily News on Nov. 13 and reposted to the Aspen Journalism website.