@COParksWildlife: Small Colorado native fish no longer “Federally Endangered” candidate

Here’s the release from Colorado Parks and Wildlife:

The Arkansas darter is a two-and-a-half inch native perch found throughout southeastern Colorado, Kansas and a few other states. On Oct. 6, 2016, after a 12-month finding, these fish were official categorized as “ not warranted” for federal listing by the U.S. Fish and Wildlife Service, bringing some relief to more than 40 years of concern for the species.

Arkansas darter were listed as threatened at the state level by Colorado Parks and Wildlife in 1975, and through a collaborative effort with FWS and other state wildlife management agencies, were designated a federal candidate species in 1991. Candidate species under the Endangered Species Act of 1973, are described as “having sufficient concern for their biological status but for which development of a proposed listing regulation is precluded by other higher priority listings.”

In 1994 (with recent updates) these status listings prompted CPW biologists to partner with the FWS and other wildlife agencies to develop an individual recovery plan for the species. The plan included ramping up conservation efforts, such as work with private landowners, habitat conservation, hatchery propagation, reintroduction and re-establishment of populations, and long term monitoring and research, among other actions.

“This ‘not warranted’ decision is a testament to the dedication and effort of many CPW staff over many years,” said Harry Crockett, CPW Native Aquatic Species Coordinator.

The decision was based on a recent status assessment of the Arkansas darter throughout its range in Arkansas, Colorado, Kansas, Missouri, and Oklahoma. Representative species biologists from each state, FWS biologists, as well as climate and hydrology scientists worked throughout 2014 and 2015 on assessing the species’ health, distribution and potential future.

“The Species Status Assessment Report for the Arkansas darter, and the FWS’s resulting 12-month finding was a superb collaboration between the affected states and the FWS,” said Vernon Tabor, Species Biologist, FWS; Arkansas darter assessment lead. “While the finding was solely FWS responsibility, we needed the excellent data, coordination and expertise we found in our state partners, including Colorado Parks and Wildlife. This allowed us to make our decision based on the most sound and recent science available.”

Threats to Arkansas darters still persist, as illustrated by their listing as a Tier One species in CPW’s 2015 State Wildlife Action Plan.

“Probably our greatest concern for the long term stability of Arkansas darters is specifically related to the future of water, especially spring water and headwater reaches, that provide good habitat on the plains of the Arkansas River Basin,” said Paul Foutz, Native Aquatic Species Biologist – CPW Southeast Region.

The darter occupy cool, clear spring-fed streams and seeps with abundant vegetation and feed primarily on invertebrates. The fish are found throughout the Arkansas River Basin, however populations are now typically isolated from one another. These populations are primarily found in the Big Sandy Creek, Chico Creek, Fountain Creek, and Rush Creek drainages, as well as several drainages north and east of Lamar, Colorado.

Historical records of Arkansas darters date back to 1889, but records were scant until a 1979-1981 CPW native fishes inventory of the Arkansas River Basin identified a far more widespread distribution of the species.

CPW will continue to make recovery and conservation of Arkansas darters a high priority.

“CPW is fully committed to continuing work to ensure that the species persists and fulfills its important niche in a fundamentally water-scarce region which is likely to become drier in the future. However, we, along with our partner agencies throughout the species’ range, can all be proud to have achieved the level of security and stability for the species that this ‘not warranted’ decision reflects,” said Crockett.

#RioGrande: Tackling The Mosaic Puzzle of a Fragile Ecosystem — Water Deeply

Rio Grande and Pecos River basins
Rio Grande and Pecos River basins

Here’s an interview with Luzma Nava from Matt Weiser and Water Deeply. Click through and read the whole thing. Here’s an excerpt:

IF THERE’S EVER been a river at the mercy of international politics, it would have to be the Rio Grande.

The river begins in southern Colorado, flows the length of New Mexico, then forms the entirety of the border between Texas and Mexico. As such, the Rio Grande (known as the Rio Bravo in Mexico) is not only the subject of water battles but also disputes involving public access, legitimate international trade, illegal drug trafficking and, of course, illegal immigration…

Several treaties govern the flow of water in the Rio Grande, as well as trade and travel across the international border. Because of intense water development and diversion, parts of the river are completely dry and fishless for hundreds of miles during much of the year. The treaties ensure that everyone who is entitled to water gets their share, on both sides of the border.

Forgotten in all this is what’s best for the river itself – its wildlife and its habitats – and for the people who simply want to enjoy a wet river. Luzma Nava recently explored this problem in a study published in the journal, Water. The study was completed while Nava was a postdoctoral fellow at the International Institute for Applied Systems Analysis, an independent think-tank based outside Vienna, Austria.

Nava, a native of Guanajuato, Mexico, is now completing a doctoral degree in international studies at Laval University in Quebec. For the Rio Grande study, Nava conducted more than 70 interviews with people involved in Rio Grande water management, on both sides of the border, and concluded that it is possible to amend the Rio Grande treaties to free up water for environmental purposes. Nava spoke recently with Water Deeply about her work…

Water Deeply: What is the condition of the river today?

Rio Grande Silvery Minnow via Wikipedia
Rio Grande Silvery Minnow via Wikipedia

Nava: If I have to answer in one word, I would say fragile. The main issue is the lack of water. Also the water quality is in danger. And when water quality of the river is not good enough, then we have ecological issues as a consequence.

The fact we don’t have enough water translates into other issues that depend on the quantity of water. There is a loss of habitat, water quality degradation, pollution, salinization, sedimentation. The community of fish is very, very low. In terms of water quality, the more fish we find in the river, the better the quality of the water. But in the case of the Rio Grande, it doesn’t work like that because there are no fish in the river. They have disappeared because there is not enough water.

#coleg: @CWCB_DNR hopes to score $25 million for watershed plans @COWaterPlan

Yampa River
Yampa River

From The Denver Post (Bruce Finley):

A Colorado Water Conservation Board proposal, sent to state lawmakers last week, recommends the stream-saving action to meet state environmental and economic goals. It remains unclear who would enforce the community watershed plans.

But there’s little doubt streams statewide are strained by thirsts of a growing population expected to double by 2060, according to state officials. And a Denver Post look at the latest water quality data found that 12,975 miles of streams across Colorado (14 percent of all stream miles) are classified as “impaired” with pollutants exceeding limits set by state regulators.

Creating local watershed plans to save streams is essential, said James Eklund, the CWCB director and architect of the year-old Colorado Water Plan. Eklund pointed to low-snow winters and drought in California’s Sierra Nevada, where 2015 snowpack at 5 percent of average forced a declaration of a state of emergency requiring 25 cuts in urban water use.

“When our Colorado mountain snowpack drops below 60 percent of average, we get nervous. If it happens in the Sierras, it can happen in the Rockies,” he said. “We need to protect certain streams before a crisis. We have got to get on this quickly.”

No single agency oversees waterway health. State natural resources officials monitor flow levels in streams and rivers. They run a program aimed at ensuring sufficient “in-stream flow” so that, even during drought, streams don’t die.

Meanwhile, the Colorado Department of Public Health and Environment sets standards on maximum levels of pollutants that people and companies are allowed to discharge into waterways. In 2015, only 51.6 percent total stream and river miles in Colorado met quality standards, and 30.1 percent of lake surface acres met standards, according to a CDPHE planning document.

“If stream flows are low, there is less dilution in the stream to handle the addition of pollutants through permitted discharges,” CDPHE water quality director Pat Pfaltzgraff said in responses sent by agency spokesman Mark Salley.

Yet CDPHE officials do not make recommendations to natural resources officials about water flows necessary to improve stream health.

The health department has made separate “watershed plans.” CDPHE officials “are considering broadening the division’s watershed plans to include ecosystem health that might be more consistent with stream management plans.”

Pfaltzgraff declined to discuss stream health…

CWCB chairman Russ George supported the push to create local watershed plans, to include detailed maps covering every stream.

“Every stream and tributary needs to be inventoried. … It should have been done a long time ago,” George said in an interview last week.

“We have kind of hit the population and demand place where we have to do it. We didn’t have to do it for the first part of history because the population was small and there wasn’t the impact of all the issues we are getting into now,” he said.

The CWCB voted unanimously last month to ask lawmakers to approve $5 million a year for up to five years to launch local stream planning.

Basin roundtable boundaries
Basin roundtable boundaries

The plans are to be developed within the eight river basin “roundtable” forums that Colorado has relied on for addressing water challenges. These groups draw in residents with interests in stream health who helped hash out the Colorado Water Plan, which was finalized last year and calls for statewide cuts in per person water use by about 1 percent a year.

Conditions along Colorado streams vary, said Bart Miller, healthy rivers program director for Boulder-based Western Resource Advocates. “There are plenty of streams that have problems.”

While state natural resources officials run the program aimed at keeping at least some water in heavily tapped streams, survival in a competitive environment is complex. Leaving water in streams for environmental purposes often depends on timing, when the mountain snowpack that serves as a time-release water tower for the West melts, the amount of snowpack, and needs of cities, pastures and farms.

Collaborative local forums to find flexibility to revive streams “is a great approach.” However, state officials eventually may have to play a central role converting plans into action, Miller said.

“The state should help both in funding the planning but also in implementing the plans,” he said. “We have a lot of work to do. This matters because this is about ‘the Colorado brand.’ Everyone depends on healthy rivers.”

The roundtable forums in communities draw in diverse stakeholders from cattlemen to anglers.

Irrigators and other water users west of Aspen already have created a “stream management plan,” for the Crystal River, seen as a model local effort. Their planning included an assessment of watershed health that found significant degradation above the confluence with the Roaring Fork River. They set a goal of reducing the estimated 433 cubic feet per second of water diverted from the river by adding 10 to 25 cfs during dry times. They’re developing “nondiversion agreements” that would pay irrigators to reduce water use when possible without hurting agriculture, combined with improving ditches and installation of sprinkler systems designed to apply water to crops more efficiently.

Enforcement of plans hasn’t been decided. “We’d like to see more enforcement” of measures to improve stream health, Rocky Mountain Sierra Club director Jim Alexee said. “We definitely think there’s room to do more. We also want to be respectful of the governor’s watershed process.”

Colorado has no history of relying on a central agency to enforce water and land use, CWCB chairman George pointed out.

“When you have a system designed to have everybody at the table, what you’re doing is recognizing there is a finite resource that is shared by everybody. And impacts are shared by everybody statewide. In order to keep from having some force dominate in ways that would not account for all statewide impacts, you need to diffuse the conversation into all areas. That is what roundtables do,” he said.

“When you do that, you’re going to get a better statewide result over time. … It is a process that is designed to get as many interests into the decision-making as you can. … It gets harder, of course, as the supply-demand makes pinches. For the rest of our lives, it is going to be that way.”

Platte River: Protected species make water projects especially important — The Kearney Hub

The Platte River is formed in western Nebraska east of the city of North Platte, Nebraska by the confluence of the North Platte and the South Platte Rivers, which both arise from snowmelt in the eastern Rockies east of the Continental Divide. Map via Wikimedia.
The Platte River is formed in western Nebraska east of the city of North Platte, Nebraska by the confluence of the North Platte and the South Platte Rivers, which both arise from snowmelt in the eastern Rockies east of the Continental Divide. Map via Wikimedia.

From The Kearney Hub (Lori Potter):

Nebraska has a unique role among the four partners in the Platte River Recovery Implementation Program, according to Nebraska Department of Natural Resources Director Jeff Fassett.

“All the (protected) species and all the habitat are in Nebraska,” he said.

The Central Platte Valley is the target area for least terns, piping plovers and whooping cranes, while pallid sturgeon are in the Lower Platte River.

All the water options for a proposed program extension, which will focus on reducing river depletions by another 40,000 [acre-feet] or more, are in Nebraska to be as close as possible to the target habitat.

Fassett said that with a major reservoir project now off the table, new projects will include groundwater recharge, facilities to hold water for retimed releases and water leasing.

He noted Tuesday at the annual convention of the Nebraska State Irrigation and Nebraska Water Resources associations that initial water projects were completed by all three states toward meeting the program’s first-increment goal to reduce river depletions by 130,000-150,000 [acre-feet].

However, more recent projects and those being considered for the future are only in Nebraska. “There is hydrologic logic about that,” Fassett said, because projects hundreds of miles from the target habitat are not as effective.

Nebraska’s benefits include regulatory stability the program provides for the Platte Basin. Projects in Nebraska, Colorado and Wyoming that must comply with the federal Endangered Species Act can do so through the program instead of individually, he said.

Another issue for Nebraska is its own demands to enhance water in the river. Fassett said state laws for the overappropriated area of the Platte Basin west of Elm Creek require “moving the train backward” to mitigate new water uses since 2007.

#ColoradoRiver: Inside the Glen Canyon Dam during a high-flow experiment #COriver — #Arizona Daily Sun

The generator building of Glen Canyon hydro power plant in Arizona via Wikimedia.
The generator building of Glen Canyon hydro power plant in Arizona via Wikimedia.

From The Arizona Daily Sun (Taylor Hartman):

In an attempt to restore some natural flow to the Colorado River, high flow experiments are conducted from Glen Canyon Dam. Taking tips from Mother Nature, these experiments mimic natural floods that occurred before the construction of the dam. On Monday, November 7, one such experiment began, freeing a large quantity of water from Lake Powell reservoir over the span of five days.

During the controlled flood, the view from the steel bridge changes: the awakened Colorado River thrashes in the canyon below. Water flows through the hydroelectric generators and erupts from four river outlet tubes, with its roar reverberating off the canyon walls and mist sparkling under the warm November sun. Dazzling white due to immense pressure, 36,000 cubic feet of water bursts from the dam every second. This peak flow is four to six times greater than usual discharge, and lasted for 92 hours.

While the bridge offers an incredible view of the dam, canyon, river and reservoir, tours bring visitors inside the dam daily. From within the cold walls of the dam, the sound of rushing water is accompanied by the rhythm of generators turning at 150 rounds per minute. During the experiment, these generators still produce hydroelectric power, but less than usual. The Bureau of Reclamation says that all power demands will still be met.

The ground floor of the dam tour is at river level, and the 710-foot dam is even more impressive when viewed from the bottom. At this level, the sound of water overpowers all other noise, and wild emerald waves crash against concrete and sandstone. As floodwaters leave the dam and travel through Grand Canyon, sediment is picked up from tributary rivers and suspended in the tumultuous flow. The experiment is timed to follow an influx of sand from the Paria River, enabling the flood to redistribute it throughout the river corridor.

Downstream, the river corridor is cleansed: low vegetation is ripped from riverbanks, beaches are submerged, and sand is suspended and deposited. The flood affects campers and rafters through Grand Canyon. People recreating near or on the Colorado River were encouraged to be on alert, camp on high, stable beaches, and practice leave-no-trace ethics. On the other side of the dam, water level at Lake Powell has dropped more than three feet.

This flood is the latest release in a series of high flow experiments since 1996. Controlled floods have the potential to enlarge sandbars and beaches downstream of Glen Canyon Dam, which could provide ecological and recreational benefits. These benefits include: improving the habitat of native fish such as the endangered humpback chub, reducing erosion of archaeological sites, restoring vegetation, and increasing the size of beaches.

As the flood ramps down, the river returns to its usual controlled flow condition. The promising white blast from the outlet tubes subsides, and the buzzing of the generators recaptures the soundscape at Glen Canyon Dam. Scientists will continue to monitor Colorado River conditions in order to understand how this flow affects downstream ecosystem and resources, and to plan future floods. The Bureau of Reclamation says that the occurrence and intensity of future high flow experiments will depend on weather, sediment influx from tributaries, and other resource conditions.

November 2012 High Flow Experiment via Protect the Flows
November 2012 High Flow Experiment via Protect the Flows

#ColoradoRiver: @CWCB_DNR approves $90 million loan for Windy Gap project — Aspen Daily News #COriver

Map from Northern Water via the Fort Collins Coloradan.
Map from Northern Water via the Fort Collins Coloradan.

From Aspen Journalism (Brent Gardner-Smith) via The Aspen Daily News:

The board of directors of the Colorado Water Conservation Board gave conceptual approval Wednesday to a $90 million loan to help finance the $400 million Windy Gap Firming Project, which will divert more water from the Colorado River.

The CWCB, charged with facilitating water supply projects in Colorado, has both a loan program and a grant program. And while its grant program is being challenged by a sharp drop in severance tax revenue from the oil and gas sector, the agency’s loan program remains robust, especially as Aurora just repaid a $70 million loan ahead of schedule.

The $90 million loan to Northern Water, which is developing Windy Gap, is the largest in the agency’s history. It will help facilitate a project that is more popular on the Eastern Slope than the Western Slope, given it will increase the level of water sent under the Continental Divide.

The loan, which still needs final approval from the CWCB board, will be part of a financing package for a new reservoir near Loveland called Chimney Hollow Reservoir, which will cost $400 million to construct.

Eric Wilkinson, the general manager of Northern Water, said he expects the project to be approved in 2017, that test drilling has begun at the dam site — next to Carter Lake Reservoir in Larimer County — and design work is well underway. Gov. Hickenlooper has also endorsed the Windy Gap project, even though final federal approval is still outstanding.

Wilkinson also said that the prospect of a CWCB loan has galvanized financing discussions among the 12 different entities – including 10 cities from Broomfield north to Greeley — who are involved in the project as members of the Northern Water Municipal Subdistrict.

“The difference that this has made cannot be overstated,” Wilkinson told the CWCB board about the loan.

Savings needed to backfill drop in severance tax funding

The $90 million loan makes up a big chunk of this year’s “projects bill,” which is submitted annually by the CWCB to the state Legislature for approval. This year’s projects bill is $165 million in all, which makes it the largest annual spending request in the history of the CWCB, which dates back to 1937.

Another big part of the projects bill is $55 million for an array of grants and loans spurred by the Colorado Water Plan, which was approved a year ago by the CWCB board and presented to the governor.

Of the $55 million, $10 million is for projects to be funded at the discretion of the CWCB directors, and $5 million is specifically for watershed restoration efforts and stream management plans, which is a nod to environmental interests in the state.

Another $10 million is used to fund the agency’s Water Supply Reserve Fund, which helps fund local water supply projects identified and approved by the nine basin roundtables around the state, including the Colorado River Basin Roundtable, which meets in Glenwood Springs.

Site of Chimney Hollow Reservoir via Northern Water.
Site of Chimney Hollow Reservoir via Northern Water.

Funding for roundtable projects is supposed to come from severance taxes paid by oil and gas producers in the state to the tune of $10 million a year. But the combination of the slowdown in the gas patch and property tax rebates given to the industry means that the CWCB is only going to see about a quarter of the severance tax revenue this year that it normally receives.

As such, the CWCB is asking the Legislature to let it spend severance tax revenue it has tucked away from the good years. That approach, however, is fraught with danger, as the Legislature is busy trying to figure out how to fill a $500 million to $800 million hole in the state’s budget, which must be balanced each year by law.

James Eklund, director of the CWCB, said the Legislature will be looking in all nooks and crannies for funds, but he’s hopeful that the approval of the state water plan last year will help convince lawmakers that the CWCB has a legitimate need for the money it has set aside for future projects.

Also in the $55 million bucket in the projects bill is a $30 million “loan guarantee fund” to help water suppliers with varying credit ratings to gain better interest rates when funding new projects together.

Eklund is sensitive to criticism that not enough has been achieved after the publication of the Colorado Water Plan a year ago, which itself was the product of an intense two-year collaborative effort among water interests in the state.

On Wednesday, he told the CWCB directors that while the Water Plan was now a year old, it was “only five days old in water years.”

“We are moving forward aggressively,” Eklund said. “And I don’t think slowly at all, especially if you look at it in water time.”

Board renews Ruedi fish-water lease

Also at last week’s CWCB meeting, Eklund said that the Ute Water Conservancy District in Grand Junction has offered to once again lease 12,000 acre-feet of water it owns in Ruedi Reservoir to the CWCB, so the agency can help maintain flows in the Colorado River, as it has done the last two years.

While the water from Ruedi benefits endangered fish in a critical 15-mile reach of the Colorado, it has also kicked up river levels in the lower Fryingpan River below Ruedi Reservoir in the late summer and fall to the consternation of some anglers.

The CWCB board also approved a $1.7 million loan for improvements to the Grand Valley Power Plant, which controls one of the senior water rights that make up the “Cameo Call” on the Colorado River above Grand Junction.

The loan to the Grand Valley Water Users Association and the Orchard Mesa Irrigation District will help cover the costs of a $5.2 million project to modernize the hydropower plant, which was built in the 1930s.

Contracts were also finalized this week with a bevy of water consultants to prepare the next edition of the Statewide Water Supply Initiative, or SWSI, which is a more technical version of the state water plan.

The SWSI plan is slated to be finished by December 2017 and is designed to inform regional water plans created by the basin roundtables, known as “basin implementation plans,” as well as provide a base of data for the next version of the more policy-driven Colorado Water Plan.

Also, State Engineer Dick Wolfe informed the CWCB board he’ll be retiring in June 2017 at age 55, after nine years in his role as the state’s top water cop.

Editor’s note: Aspen Journalism and the Aspen Daily News are collaborating on coverage of rivers and water in Colorado. More at http://www.aspenjournalism.org.

Center for #ColoradoRiver Studies: Fill Mead first — A Technical Assessment #COriver

fillmeadfirstatechnicalassessment

Click here to the Denver for Colorado River Studies at Utah State University for all the inside skinny on the report. Here’s the executive summary:

The Fill Mead First (FMF) plan would establish Lake Mead reservoir as the primary water storage facility of the main-stem Colorado River and would relegate Lake Powell reservoir to a secondary water storage facility to be used only when Lake Mead is full. The objectives of the FMF plan are to re-expose some of Glen Canyon’s sandstone walls that are now inundated, begin the process of re-creating a riverine ecosystem in Glen Canyon, restore a more natural streamflow, temperature, and sediment-supply regime of the Colorado River in the Grand Canyon ecosystem, and reduce system-wide water losses caused by evaporation and movement of reservoir water into ground-water storage. The FMF plan would be implemented in three phases. Phase I would involve lowering Lake Powell to the minimum elevation at which hydroelectricity can still be produced (called minimum power pool elevation): 3490 ft asl (feet above sea level). At this elevation, the water surface area of Lake Powell is approximately 77 mi2, which is 31% of the surface area when the reservoir is full. Phase II of the FMF plan would involve lowering Lake Powell to dead pool elevation (3370 ft asl), abandoning hydroelectricity generation, and releasing water only through the river outlets. The water surface area of Lake Powell at dead pool is approximately 32 mi2 and is 13% of the reservoir surface area when it is full. Implementation of Phase III would necessitate drilling new diversion tunnels around Glen Canyon Dam in order to eliminate all water storage at Lake Powell. In this paper, we summarize the FMF plan and identify critical details about the plan’s implementation that are presently unknown. We estimate changes in evaporation losses and groundwater storage that would occur if the FMF plan was implemented, based on review of existing data and published reports. We also discuss significant river-ecosystem issues that would arise if the plan was implemented.

From The Grand Junction Daily Sentinel (Gary Harmon):

Making Lake Mead the primary water storage facility on the Colorado River isn’t as simple as it might seem and would require more study than it’s been given so far, says a study released Thursday.

Backers of the Fill Mead First idea said the study underscores the need to move ahead with studies and a spokesman for the Colorado River Water Conservation District said the discussion ignores a significant element: the need for Colorado and other states to save water in Powell.

The Center for Colorado River Studies at Utah State University said more study of evaporation from Lake Powell is needed, as well as a study of groundwater into the reservoir and of the fine sediment that would be released should Lake Powell be drained.

That would be a good start, said Eric Balken, executive director of the Glen Canyon Institute, which drafted the idea of filling Lake Mead instead of storing water in Powell so as to reduce water lost to evaporation.

The Interior Department has so far “written off” the idea, Balken said.

“Now is the time to initiate new measurement programs of (evaporation) losses at Lake Powell and Lake Mead so that future policy discussions have access to less uncertain data regarding evaporation and groundwater storage,” Balken said in an email.

The idea ignores Lake Powell’s “primary purpose,” which is to serve as a savings account for the upper Colorado River Basin states to deliver an average 7.5 million acre-feet of water per year to the lower basin, said Chris Treese of the River District.

The amount is set in the 1922 compact that governs the use of the river, which provides water to millions of people in the arid Southwest.

Advocates of draining Lake Powell tend to write off the upper basin concerns by saying it’s “with a wave of the hand that you’d have to ‘make a few changes’,” to the compact, Treese said, “As if it’s simple and desirable to open up the Colorado River Compact.”

The Fill Mead First idea proposes draining Lake Powell in a three-stage process and storing the water in Lake Mead, 300 miles downstream.

“It is surprising how much uncertainty there is in estimating losses associated with reservoir storage,” said Jack Schmidt of the Center for Colorado River Studies, who served as chief of the U.S. Geological Survey’s Grand Canyon Research and Monitoring Center from 2011 to 2014.

Evaporation losses at Lake Mead are measured by the U.S. Geological Survey in a state-of-the-science program, but there have been no efforts to measure evaporation at Lake Powell since the mid-1970s, Schmidt said.

Using the most recent data, researchers showed the Fill Mead First plan might reduce evaporation losses slightly, but noted that such a prediction is uncertain.

The Interior Department should conduct a thorough scientific investigation of evaporation and seepage losses at lakes Powell and Mead, as the Utah State study suggests, Balken said.

Delph Carpenter's 1922 Colorado River Basin map with Lake Mead and Lake Powell
Delph Carpenter’s 1922 Colorado River Basin map with Lake Mead and Lake Powell