Good Tony Barnston explainer of current El Nino — John Fleck

Former Interior Secretary Ken Salazar to speak at Colorado State University Water Tables event in January

Here’s the release from Colorado State University (Kate Hawthorne Jeracki):

The Honorable Ken Salazar, former U.S. Secretary of the Interior, will be the keynote speaker at the annual Colorado State University Water Resources Archive Water Tables event Jan. 29, 6:15-9:15 p.m., at the Hyatt Regency Denver Tech Center.

The theme of this year’s evening is Partnering the Waters. Two dozen tables will be hosted by experts on how partnerships – public/private, regulation/conservation, education/industry, ranching/recreation – affect the health of rivers in Colorado and throughout the West.

Attendees can join any table on a first-come, first-served basis for 90 minutes of discussion and dinner, followed by Secretary Salazar’s remarks, dessert and more conversation. Water Tables will be preceded by a reception, 5-6:15 p.m., hosted by the Colorado Water Congress.

Some of the table topics include the recently released Colorado Water Plan; Climate Change, Resiliency and Adaptation; Extreme Drought; and Diversion Dam Removal on the South Platte River. Tables will be hosted by Patty Rettig, Head Archivist of the Water Resources Archive; historian George Sibley; John Sanderson, director of science for The Nature Conservancy; James Ecklund, director of the Colorado Water Conservation Board; and Patricia Wells, general counsel for Denver Water, among others.

Salazar, a fifth-generation Coloradan, also served as the state’s 35th U.S. Senator. He was a key leader in creating the successful energy framework created by the 2005 Energy Policy Act, the 2006 Gulf of Mexico Security Act, and the 2007 Energy Independence and Security Act, all of which passed the Congress and were signed by the President. He also was recognized for his leadership on conservation, veterans, agricultural and immigration reform matters. He is now a partner in the global law firm of Wilmer-Hale.

Water Tables is a fundraiser for the CSU Water Resources Archive and open to the public.

Tickets cost $150, which includes a $75 gift to the Archive. More information and registration is available at
Water Tables is held in conjunction with the 2015 Colorado Water Congress Annual Convention, Jan. 28-30, also at the Hyatt Regency DTC. The premier water industry event in the state attracts 500+ attendees who convene for networking and collaboration on the important water issues of the day. This year’s theme is Rethinking Water. Experts from across the state will celebrate successes in water management innovation and plan towards a future with new ideas and flexible philosophies.

Learn more, view the agenda, and register at:

Cortez rates going up

Cortez early 1900s via Crow Canyon Archaeological Center
Cortez early 1900s via Crow Canyon Archaeological Center

From the Cortez Journal (Tobie Baker):

Public works officials said a “slight” rate adjustment was needed next year to keep up with the rising cost of infrastructure repairs, treatment chemicals and capital expenditures. Water rates will increase 5 percent in 2015.

The measure means a resident with a ¾-inch water meter, which includes the first 1,000 gallons, would pay $16.30 per month in 2015, an increase of 80 cents per month over current rates.

Rates for water usage over 1,000 gallons will also rise next year, from $2.10 to $2.20, and so will fees for the commercial water dock, increasing in 2015 from $12 for 1,000 gallons to $12.50.

The city will also raise its current tap fee of $3,800 to $3,900, starting Jan. 1.

The city’s 2015 water enterprise fund will receive more than $4.1 million in appropriations, which includes nearly $730,000 for personnel services, $670,000 for commodities and $1.85 million for capital projects.

More infrastructure coverage here.

“Our agriculture water is the low-hanging fruit” — J. Paul Brown

Basin roundtable boundaries
Basin roundtable boundaries

From The Grand Junction Daily Sentinel (Dennis Webb):

Protecting Western Slope agriculture appears to be one area of agreement as the region looks for ways of speaking with one voice on Colorado water issues. That was one takeaway from what was effectively a Western Slope water summit held [December 18] in Grand Junction with the goal of presenting some consolidated messages on the state’s newly drafted water plan.

Members of four roundtable groups — representing the Gunnison and Colorado river basins, southwest Colorado and the Yampa, White and Green river basins — already have developed their own plans that were incorporated into the newly completed draft plan. Representatives from all those roundtables gathered Thursday to talk about common themes that have emerged that they can be jointly voicing to the rest of the state as a final plan is developed.

In the case of agriculture, Colorado roundtable basin chair Jim Pokrandt said it’s important that the state not engage in poor water planning that forces farmers and ranchers out of business.

Said state Rep. J. Paul Brown, R-Ignacio, who works in agriculture himself, “Our agriculture water is the low-hanging fruit. It’s the easy water to buy and that’s exactly what’s happened.”

He talked about a need for more Front Range storage of its own water and alternatives like bringing in water from the Missouri River “so you’re not buying that agricultural water.”

Jim Spehar, a former Mesa County commissioner and Grand Junction mayor, agreed about the importance of considering agriculture in state water planning.

“If this discussion isn’t done by and for agriculture I think it will be done to agriculture,” he said.

Thursday’s discussion also turned to other areas including municipal and agriculture conservation. Gunnison County rancher Ken Spann said one thing those in agriculture need to know is where any water they might free up from conservation would go. He’d like to see it help fill Lake Powell to help states in the Upper Colorado River basin meet interstate compact water obligations.

But he worries that instead it could just end up supplying another new subdivision, or perhaps simply being offset by new water use being sought in the Yampa basin, which would mean no net increase in Colorado River water reaching Powell.

“The trade-offs (from conservation efforts) have to be identified and we are now at the point where we have to do that or people won’t play,” he said.

Western Slope water interests plan to continue talking about seeking a unified voice on water, including by addressing issues such as a somewhat controversial proposed framework for discussing any possible new diversions of western Colorado water to the Front Range.

“This is just the start of the West Slope conversation,” said Moffat County rancher T. Wright Dickinson, who also sits on Colorado’s Interbasin Compact Committee, a statewide forum for discussing water issues.

More IBCC — basin roundtables coverage here.

Report Documents Initial Results of Environmental Water Release on the #ColoradoRiver — IBWC

The Colorado River Delta in May, 2014. Photo courtesy NASA.
The Colorado River Delta in May, 2014. Photo courtesy NASA.

Here’s the release from the International Boundary Waters Commission (Sally Spener/Gilbert Anaya):

The International Boundary and Waters Commission, United States and Mexico (IBWC) today released the Initial Progress Report for the Minute 319 Colorado River Delta Environmental Flows Monitoring. The report documents initial success in delivering water to key areas in order to promote habitat restoration in the Colorado River riparian corridor.

Minute 319 is a 2012 IBWC agreement on U.S.-Mexico cooperation on a variety of Colorado River issues, including the environment. The Minute provides for a pulse flow — a one-time event to deliver water to the environment in the Colorado River Delta in Mexico. The pulse flow release, totaling approximately 105,392 acre-feet (130 million cubic meters) began March 23, 2014 and ended May 18, 2014. The water was intended to help restore native vegetation and wildlife habitat in parts of the Colorado River and its Delta that usually have little to no water.

A team of scientists, environmental experts, and technical personnel from universities, non- governmental organizations, and federal agencies from the United States and Mexico closely monitored the pulse flow under the Commission’s coordination. Their Initial Progress Report documents the inundation of 4,522 acres (1,830 hectares) of river channel and floodplain, including key habitat restoration sites. The report confirms the river’s temporary reconnection with the sea. Scientists also observed that a significant amount of water infiltrated to groundwater. Another key finding is the pulse flow’s effect in dispersing seeds and germinating both non-native and native vegetation, including cottonwood and willow, two species important to ongoing habitat restoration efforts. Preliminary observations further indicate an increase of migratory bird species along open water areas and at the active restoration sites.

“The report shows we were successful in delivering environmental water to key areas. I look forward to hearing from our team of scientists as they continue to study the pulse flow’s impact on our habitat restoration efforts,” said U.S. Commissioner Edward Drusina of the IBWC.

Mexican Commissioner Roberto F. Salmon Castelo indicated that these preliminary results confirm that nature always reacts positively even to small efforts like this one that was included in Minute 319, and that this will certainly prompt continued consideration of this type of action in subsequent agreements that could be generated with respect to Colorado River cooperation between both countries.

A mid-term report on the pulse flow is expected in 2016 and the final comprehensive report is expected in 2018.

The Environmental Pulse Flow Initial Progress Report is available on the website of the U.S. Section of the IBWC at: A summary of Minute 319 is available at:

Interviews with scientists who worked on the report can be arranged upon request.

Here’s a release from the United States Geological Survery:

A pulse of water released down the lower reaches of the Colorado River last spring resulted in more than a 40 percent increase in green vegetation where the water flowed, as seen by the Landsat 8 satellite. The March 2014 release of water – an experimental flow implemented under a U.S.-Mexico agreement called “Minute 319” – reversed a 13-year decline in the greenness along the delta.

The year 2000 was the last time the Colorado River reached the Sea of Cortez, between Mexico’s mainland and Baja California. Since then, said Pamela Nagler of the U.S. Geological Survey’s Southwest Biological Science Center in Tucson, Arizona, information from ground measurements and satellites, including NASA/USGS’s Landsat missions and the Moderate Resolution Imaging Spectroradiometer, or MODIS, instrument on NASA’s Terra satellite, have shown a decline in the amount of healthy vegetation along the lower reaches of the river.

This spring’s pulse flow brought back some of the green. Nagler and other members of the Minute 319 Science Team used Landsat 8’s sensors to track the response of plants to the pulse of water. Landsat 8 is a joint project of NASA and the U.S. Geological Survey (USGS).

“The vegetation that desperately needed water was finally able to support more green leaves,” Nagler said. “These are existing trees, like saltcedar, willow and cottonwood, and a lot of shrubs and grasses that hadn’t seen much water in a long time.”

When they compared satellite images of pre-flow August 2013 to post-flow August 2014, the researchers calculated a 43 percent increase in green vegetation along the route wetted by the flow, called the inundation zone, and a 23 percent increase in greening of the riparian zone, or the river banks. Scientists presented these and other results this week at the American Geophysical Union’s Fall Meeting in San Francisco.


“Data from Landsat and the MODIS sensor are well-suited to help people make informed policy decisions about ecosystem health, water management, agriculture and much more,” said Jim Irons, Landsat 8 project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “It’s especially gratifying to see these sensors help scientists evaluate several of those components in one project,” he said. Remote sensing data were used in studies showing the impact of other relatively small flows prior to the Minute 319 agreement, and researchers are currently using Landsat 8 and MODIS to continue studying the effects of the 2014 water release.

Irons said that projects like this one demonstrate that researchers need an archive of good Earth observations of the past to refer to, as well as comparable measurements into the future to measure how a policy changes the landscape. “It’s important to have continuity of the data, so that when a policy decision is made to release the water, we have a system in place to evaluate its effects,” he said.

The Minute 319 pulse flow is part of an agreement adopted by the International Boundary and Water Commission, under the framework of a 1944 U.S.- Mexico treaty that governs water allocations on the Colorado River between the two countries. The 2012 agreement prescribed 130 million cubic meters (105,000 acre feet) of water to flow through Morelos Dam, which straddles the border.

Although most of the water soaked into the ground in the 37 miles below the dam, the river’s surface flow reached areas farther downstream that had been targeted for restoration, and groundwater revived vegetation along the entire route to the sea.

“Remote sensing with satellites such as Landsat and sensors such as MODIS allows scientists to conduct a range of studies they wouldn’t otherwise be able to,” said Karl Flessa, the co-chief scientist of the Minute 319 Science Team studying the hydrologic and biologic effects, and a geosciences professor at the University of Arizona in Tucson.

It’s just one of the tools scientists are using, along with on-the-ground monitoring, to detect changes in the river channel, surface water, groundwater, plant growth, and habitat for resident marsh birds and migratory birds.

“In addition to remote sensing, ground-based geophysical methods such as time-lapse gravity maps provide information about the change in groundwater storage, which ultimately supports riparian vegetation,” said Jeff Kennedy, USGS hydrologist and participant in the study.

The Minute 319 pulse flow was the result of significant cooperation between a large group of partner organizations and agencies in the U.S. and Mexico.

With so many interested parties, and water such a precious resource, scientists will continue to monitor the lower Colorado River Delta’s vegetation and hydrological response to the pulse flow, Flessa said. Using greenness data collected both from the ground and from satellites, researchers will investigate the long-term impacts to groundwater, and they’ll continue to study whether new trees and shrubs take root due to the flow. They will also study how the new vegetation affects birds migrating along the Pacific Flyway.

“There’s hope that we could release a pulse of water below Morelos Dam again,” Flessa said.

More Minute 319 coverage here.

Feds ink $300 million Windy Gap water diversion out of #ColoradoRiver — The Denver Post

Site of proposed Chimney Hollow Reservoir -- Windy Gap Firming Project via the Longmont Times-Call
Site of proposed Chimney Hollow Reservoir — Windy Gap Firming Project via the Longmont Times-Call

From The Denver Post (Bruce Finley):

Federal water authorities signed off Friday on the $300 million Windy Gap Firming Project to siphon more water out of the Colorado River Basin into a huge new reservoir for the high-growth Front Range.

The west-flowing river water — up to 8.4 billion gallons a year pumped back eastward and under the Continental Divide — is expected to meet the needs of 400,000 residents around Broomfield, Longmont, Loveland and Greeley.

A U.S. Bureau of Reclamation decision clears Northern Water to build the 29 billion-gallon Chimney Hollow Reservoir, assuming it obtains state water quality and federal wetlands permits.

The reservoir would sit southwest of Loveland, west of Carter Lake. Work would begin by 2018, Northern Water spokesman Brian Werner said.

“It’s going to make water supplies more reliable,” Werner said. “You want to make sure you have a firm supply year in, year out so you have water for the basic needs of your communities.

“With all the growth we’ve seen in northern Colorado, we keep pushing that envelope of how close we are when that really dry year hits. We’ve got a lot more people moving in — one of the fastest-growing populations in the country — and part of this is about preparing for the future.”

For more than a decade, western Colorado communities have fought the project, contending it will degrade the ailing Colorado River Basin.

The project would divert river water near Granby and pump it through an existing 9-foot-diameter tunnel under the Continental Divide, to be stored in Chimney Hollow.

Numerous studies have found this will increase environmental harm that began in the 1930s, when federal agencies began pumping west-flowing water back eastward, through the Adams, Moffat and other tunnels, to Colorado’s semi-arid Front Range. Water temperatures spiked. Algae spread. Sediment clogged channels and choked aquatic life.

Negotiations during the past six years led to plans to try to minimize environmental harm and offset damage.

Northern Water has agreed to:

• Install temperature-monitoring devices and not divert water when the river gets too warm.

• Release trapped water for 50 hours at least once every three years, ensuring flows of 600 cubic feet per second, to simulate natural floods essential for ecosystem health.

• Give 977 million gallons a year to Grand County.

The project would increase the amount Northern Water diverts annually to more than 250,000 acre-feet, bringing total water diverted from the Colorado River Basin to 67 percent of the natural flows. Northern Water supplies 33 cities and irrigation water for 650,000 acres of crops.

From KUNC (Nathan Heffel):

The record of decision states that the proposed Chimney Hollow Reservoir site is the preferred location for holding water transported from the Western Slope via the Colorado Big Thompson Water Project. The proposed reservoir would feed 10 municipalities across Northern Colorado including Greeley, Loveland and Fort Lupton.

Northern Water’s Brian Werner said this is an important step in a long process bringing, what he calls, water stability to Northern Colorado users.

“We have two steps remaining next year [2015], we need a state water quality certification and then a wetlands permit from the Army Corps of Engineers,” Werner said. “Once those steps happen we move forward with design, that’s probably a year, year and a half. And then we can start going out to bid and onto construction.”

Werner said a 2017 or 2018 ground breaking on the project is likely.

Project managers said the Windy Gap Firming Project could provide 26,000 acre-feet of additional yearly water to Northern Colorado cities if constructed. Currently that additional water is lost in years of high run-off since there’s no place to hold it. During low run-off years, water is unavailable because the Windy Gap Project holds junior water rights.

“This makes reliable a water supply to a number of Northern Colorado communities that haven’t had the reliability factor with their Windy Gap water supplies. So it gives them another comfort level in terms of future water supplies,” Werner said.

“With the drought throughout the Colorado River basin and always on people’s minds, this is a huge step in terms of finding and putting together a future water supply for these communities.”

The federal permitting process for the project began in 2003, and the Bureau of Reclamation issued a final Environmental Impact Statement in 2011. A fish and wildlife mitigation plan was also approved at that time by the Colorado Parks and Wildlife Commission.

More Windy Gap coverage here and here.

Creating a secure water future for south metro Denver — The Denver Post #COWaterPlan

CWCB director James Eklund with manager in Water Supply Planning, Jacob Bornstein bring  a box containing the draft water plan to the Capitol.
CWCB director James Eklund with manager in Water Supply Planning, Jacob Bornstein bring a box containing the draft water plan to the Capitol.

Here’s a column about the south metro area and Colorado’s Water Plan from Eric Hecox that’s running in The Denver Post:

Colorado took an important step in addressing the state’s long-term water challenges by completing a draft of a state water plan. The plan offers a foundation from which local and regional water entities can work as we pursue solutions that balance local needs with statewide priorities. One need only look to the suburbs south of Denver to find many of the plan’s key tenets in action and a picture of what an effective “all-of-the-above” strategy looks like.

The water challenges facing the south metro region are well known. Historically we have relied too heavily on non-renewable underground aquifers. We must transfer to a secure, sustainable supply to protect property values, jobs, our economy and our quality of life.

What’s less known is the progress we have made. In the late 1990s, aquifer declines averaged 30 feet per year. This has dropped to an average of 5 feet per year today. A decade ago, about 70 percent of our region’s water came from non-renewable sources. By 2020, that will be reduced to 45 percent. Some communities, including Highlands Ranch, are close to or have cut that number to zero.

While we still have work to do, we have made tremendous progress in short time because we followed an “all-of-the-above” approach that mirrors the one advocated by state water leaders.

The approach begins with conservation. The south Denver metro region has reduced per capita water use by more than 30 percent since 2000. A few examples of local efforts:

• Providers serving Highlands Ranch and Castle Rock are two of only three in the state to put water customers on a water budget that tracks use by household.

• Sterling Ranch is conducting the state’s first rainwater harvesting pilot study.

• Inverness provides rebates for replacing turf with low water use landscaping.

Being a good steward of our limited water resources means more than conserving, however. It also means being as efficient as possible with this precious resource, which is why the state plan makes water reuse a priority. Here, too, the south metro region is leading, with all of our providers reusing their reusable water supplies or planning to:

• Inverness Water and Sanitation and the Meridian Metropolitan District are among the earliest adopters of water reuse in Colorado. They reuse 100 percent of collected wastewater.

• Castle Rock recently completed the Plum Creek Water Purification Facility as part of its goal of attaining a 75 percent renewable water source.

Increased water storage is another component of the statewide plan that the south metro area has put to action:

• The recently completed Rueter-Hess Reservoir provides storage to Parker and three other South Metro Water members. When filled, the reservoir will be 50 percent larger than Cherry Creek Reservoir.

• The expansion of Chatfield Reservoir is a collaboration among nine entities, including four South Metro Water members, to add storage to an existing reservoir.

Regional cooperation is another key tenet of the state water plan that is playing out in the south Denver suburbs. Through local and regional partnerships, we are getting more use out of existing infrastructure and supplies.

The WISE Project is a first-of-its-kind partnership with Denver Water and Aurora Water that bolsters water supplies to the south Denver suburbs while maximizing existing water assets in Denver and Aurora. Similarly, Arapahoe County Water and Wastewater Authority and East Cherry Creek Valley partnered to complete a state-of-the-art water treatment plant in 2012 and are working with several other South Metro Water members to share capacity on the ECCV Northern Pipeline.

The Colorado Water Plan provides a helpful roadmap. Born out of necessity, South Metro Water is proud to lead the way toward a secure and sustainable water future.

From the Sky-Hi Daily News (Hank Shell):

Western Slope water interests still reeling from the Gross Expansion Project may barely have enough time to catch their breath before they’re again summoned to the bargaining table…

Regarding another diversion, the plan “seeks to find a path forward that considers the option of developing a new (trans-mountain diversion), while addressing many of the concerns expressed by the Colorado Basin roundtable and others.”

The threat of another trans-mountain diversion has loomed behind the development of localized basin implementation plans for each of Colorado’s eight largest river basins.

The South Platte/Metro Basin roundtables have called for new Colorado River water supplies since their draft plan was released this summer.

The state water plan outlines seven “points of consensus” for a new diversion, one of which states that the Eastern Slope isn’t seeking firm yield from a new diversion, and that it “would accept hydrologic risk for that project.”

But Grand County Manager Lurline Underbrink Curran said many of those points are overly vague.

“What does risk mean?,” Curran said. “What does a new (trans-mountain diversion) mean? What does that mean when you have millions of people relying on it? The devil is in the details.”

Grand County has been active in the Colorado Basin Roundtable, which has actively opposed any new trans-mountain diversion from the Colorado River.

Jim Pokrandt, chair of the Colorado Basin Roundtable, said in an email that the Western Slope basin roundtables would probably draft an official response at their Dec. 18 meeting in Grand Junction.

Pokrandt did provide a list of points from a November discussion, in which the Colorado Basin Roundtable calls it “premature” to include the seven points in the state water plan.

“We need to recognize that there may come a point where we cannot back down,” the document states, “where we will need to take a stand for the sake of the West Slope and Colorado as a whole.”

In past discussions, Pokrandt has maintained that any additional diversions from the Colorado River could trigger a compact call, in which junior water rights holders must stop diverting to supply Lower Basin states with water.

A compact call could impact municipal and other users on the West Slope, including the Colorado-Big Thompson Project.

Each basin will submit its final basin implementation plan to the Colorado Water Conservation Board in April 2015. The board will submit its final state water plan to the governor in December 2015.

To view the draft state water plan, visit

More Colorado Water Plan coverage here.

Water Lines: Cloud seeding can work, but it won’t fill Lake Powell — Grand Junction Free Press

Cloud-seeding graphic via Science Matters
Cloud-seeding graphic via Science Matters

From the Grand Junction Free Press (Hannah Holm):

In the arid West, the perpetual search for new water supplies, like the mythical search for the Holy Grail, has given rise to numerous fantastical adventures and grand schemes. Some of these have resulted in the impressive feats of engineering that have re-plumbed much of the Colorado River Basin, and some have remained fantasies, like towing ice bergs from the Arctic and building pipelines from the Great Lakes.

“Cloud seeding” to wring more moisture from the sky has long been hard to classify in those terms. Water agencies and ski resorts have been doing it for decades, mostly by sending plumes of silver iodide from ground-based burners into likely-looking clouds. Cloud seeding has been done in Colorado since the 1950s and ramped up significantly after the 2002 drought. Still, until recently, no one could say with any certainty if cloud seeding really worked, or if so how well.

Draft conclusions from a much-anticipated, very rigorous nine-year study conducted in Wyoming indicate that cloud seeding can, in fact, increase the water yield from some storms, but the ultimate effect on the water supply is quite modest. The draft executive summary of the Wyoming Weather Modification Pilot Program study, conducted by numerous collaborators, was presented to the Wyoming Water Development Commission on Dec. 10; it is due to be finalized in March of 2015.

The study combined physical, modeling and statistical studies of the effects of cloud seeding in Wyoming’s Medicine Bow, Sierra Madre and Wind River Ranges and concluded that seeding could increase snow accumulations from some storms by 5-15 percent. This does not, however, translate to a 5-15 percent increase in the seasonal snowpack because not all storms are “seedable,” and those that are cover only a limited area.

In order for the inserted silver iodide to stimulate significant additional snowfall, atmospheric temperatures must be below 17 degrees Fahrenheit, with sufficient moisture in the air and favorable winds. These conditions were met less than one-third of the time during the winter in the study area. Using modeling, the study concluded that increased precipitation from seeded storms of 5-15 percent affecting 30-80 percent of the cloud-seeding impact area could increase streamflow in Wyoming’s portion of the North Platte River Basin between 0.4 to 3.7 percent.

Depending on numerous factors related to the operations of the cloud seeding program, the cost-per-acre-foot of water produced through cloud seeding ranges from $27-$427 per acre-foot. This compares favorably with other options for producing “new water.” In a 2013 article in the Mountain Town News, Allen Best reports that the Bureau of Reclamation has estimated that desalting brackish groundwater in Arizona would cost $650 per acre-foot, and desalting ocean water near Los Angeles would cost $2,100 per acre-foot. Cost estimates for building new storage reservoirs run from a few hundred dollars per acre-foot to over $1,000 per acre-foot.

In addition to assessing the potential impact of cloud seeding as a feasible strategy for impacting Wyoming water supplies, the study also assessed the environmental impacts of seeding and impacts on precipitation outside the seeded area (i.e. does it steal water from downwinders?).

The environmental analysis found that concentrations of silver iodide in the affected snowpack was in the parts per trillion range, while concentrations already in the soil were much higher, in the parts per billion range, indicating a very minimal impact from cloud seeding. Modeling of impacts on precipitation outside the seeded area indicated effects of less than 0.5 percent, which is consistent with previous studies and undermines claims that cloud seeding injures those downwind of seeded areas.

This study indicates that cloud seeding likely deserves its relatively newfound respectability as a water supply strategy, but also that its impacts are far too small for it to be a panacea for the West’s water woes.

To read the draft executive summary for yourself, go to the Wyoming Water Development Commission’s website at

More cloud seeding coverage here.