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Water & Growth in Colorado

By Peter Nichols

Although conventional wisdom holds that water availability controls growth, that notion is simply not true. The demise of Two Forks Dam in 1990, designed to meet metro Denver's water needs this century, did not slow growth. In fact, since 1990, the fastest growing states (including Colorado) rank among the driest. This apparent contradiction can exist because the western system of water allocation—the prior appropriation doctrine—rests on the premise that water can be moved from where it is found to where it is needed.


New Growth: Same Basic Water Supply
Colorado gained almost a million new residents from 1990 to 2000. The state demographer projects another 2.8 million new Coloradans by 2030. The majority—1.9 million—will reside in the urban Front Range (Colorado Springs to Fort Collins), where most of the state's population already lives. Although the West Slope will grow faster than the Front Range, it will gain almost 250,000 new residents in the same period.

The Colorado Water Conservation Board's Statewide Water Supply Investigation (SWSI) projects that new residents will require an additional 600,000 acre-feet of municipal water by 2030. The Front Range will need 75 percent of the total.

Yet meeting the water needs of population growth is not as simple as supplying additional water to Front Range municipalities. To satisfy growth, Colorado needs more water for drinking, more water for industrial and commercial uses, and more water for recreation—snow to ski, rivers to raft and kayak, and streams and lakes to fish and boat—not to mention water to grow the food we eat, and for aquatic ecosystems. Meeting future demands is further complicated by the fact that over 80 percent of current and future Coloradans live on the Front Range, while 86 percent of the state's water originates elsewhere (primarily as snow on the West Slope).

Historical Water Supply Solutions
Coloradans have historically met their municipal growth needs and solved the problems of uneven distribution of population and water by constructing new on-stream reservoirs and trans-mountain water diversions to the Front Range. Denver's Dillon Reservoir exemplifies this approach, as does Colorado Springs' and Aurora's Homestake Reservoir.

Windy Gap—the last major trans-mountain project—came on line in 1985, 18 years after conception. Later proposals floundered under pressure from environmental interests and the communities that stood to lose their water. EPA vetoed Two Forks Reservoir in 1990. Opposition from watersheds where water supplies would originate, commonly referred to as ‘basins-of-origin,’ defeated exports proposed by American Water Development, Inc. from the San Luis Valley in 1994, and by Arapahoe County from the Gunnison River in 1995, and again in 2000 in water court. Eagle County stopped the proposed Homestake II Reservoir using state-granted ‘1041’ local land-use authority in the 1990s.

Beginning in the 1950s, Colorado also began to meet the demands of growth by reallocating agricultural water to municipal use. Irrigated acreage in the Arkansas River Basin declined from over 600,000 acres in 1950 to less than 435,000 acres today, a 28 percent loss in 50 years. A similar trend is evident in the Lower South Platte River Basin, where agricultural to municipal water right changes totaled 653,000 acre-feet from 1979 through 1995. Municipal and industrial users now own over 90 percent of Twin Lakes Canal and Reservoir Company shares, and approximately 60 percent of Colorado-Big Thompson units, two of Colorado's largest trans-mountain irrigation projects. These trends not only continue, they appear to be accelerating.

However, traditional approaches to supplying water for growth often had unmitigated economic and environmental consequences. Transferring irrigation water to cities often led to dried up farms and ranches, weed and dust problems, and declining agricultural communities. Ordway, for example—a once-thriving agricultural center—is now more reminiscent of ghost towns after the gold rush.

Historic on-stream dams and trans-mountain diversions have also had mixed effects on tourism and recreation, an $8.5 billion industry. The 2002 drought illustrates this. The Arkansas River normally hosts the most commercial rafting days in the nation, in excess of 250,000 rafting days per year. This fell by almost half during the low river flows of 2002. Simultaneously, commercial rafting days on the Colorado River grew 50 percent because senior downstream water rights supported by upstream storage kept the water flowing. Because popular recreational sites like Dillon, Ruedi, and Turquoise lakes exist in part to meet municipal water needs, they experience low water levels when exports to the Front Range are at their maximum. Although constructed as water supply reservoirs, the public is often both unaware and uninterested in this fact, and sees them primarily as recreational amenities.

Low flows can harm aquatic ecosystems as well. For example, popular fisheries on the South Platte, Arkansas, and Fryingpan experience diminished flows from municipal diversions to serve the Front Range, although these same rivers also benefit from water released from reservoirs constructed in part to meet municipal needs. A 2002 poll by the Colorado Water Trust of state and federal agencies and conservation organizations identified several thousand miles of water-short streams in the state, nearly as many miles as are already protected by the Colorado Water Conservation Board's instream flow program.

Alternatives for the Future

Alternatives for the future can be seen in a number of innovative cooperative approaches, many of which have already been completed or are now under way.

New Development
New cooperative water development projects, reservoir redevelopment, and storage reallocation can benefit the basins where water supplies would originate. Front Range providers are increasingly proposing such projects to avoid opposition. For example, Wolford Mountain Reservoir is a win-win project benefiting both sides of the Continental Divide. Funded by Denver Water, the Municipal Subdistrict of the Northern Colorado Water Conservancy District, and the Colorado River District, this reservoir allows Denver, by exchange, to keep more water in Dillon Reservoir, provides water for the River District, and serves as mitigation for Northern's Windy Gap Project.

Reallocation of existing storage space to different uses presents another alternative to new reservoirs. Clinton Gulch Reservoir, a former mining structure, is a cooperative project that now provides Summit and Grand counties with water for domestic use and snowmaking. The Colorado River District and Denver Water also benefit, helping Denver to capture more melting snow in Dillon Reservoir and the River District to develop more water in western Colorado.

Redevelopment offers a similar alternative to new development. For example, Vail-area communities, Vail Resorts, Colorado Springs, Aurora and the Colorado River District redeveloped an old mine tailings pond to create a new storage facility called Eagle Park.

Off-channel reservoirs provide another alternative to on-stream dams. For example, the Parker Water and Sanitation District plans to construct Reuter-Hess Reservoir, an off-channel storage facility to serve the groundwater-dependent town of Parker in Douglas County.

Conjunctive use of groundwater and surface water offers many of the storage possibilities of new water development, with fewer environmental impacts. Conjunctive use involves taking excess surface water collected in wet years, and pumping it into groundwater aquifers for extraction as drought or need requires. The South Metro Water Supply Study, involving 11 Douglas County water suppliers, Denver Water, and the Colorado River District, is exploring a project that would provide new long-term supplies for groundwater-dependent Douglas County water agencies, using a combination of existing Denver Water reservoirs, new storage in the South Platte Basin, and conjunctive use of groundwater.

Reallocation of Existing Supplies: Farms to Cities
Agricultural to urban transfers will continue to supply at least a portion of the state's future population growth for the simple reason that municipal water is worth 20 times as much as agricultural water, and there are fewer regulatory hurdles associated with such transfers. The long-term challenge for Colorado is to manage these transfers in a way that minimizes negative impacts and fosters healthy agricultural economies and communities.
However, the immediate challenge is to switch from permanent to temporary transfers in order to provide time to develop long-term solutions. I

nterruptible supply agreements (sometimes called dry-year option agreements) allow municipalities to lease agricultural water for intermediate (up to ten year) terms, and to use that water in abnormally dry years.

For example, in the Lower Arkansas River Basin, Aurora recently leased up to 12,600 acre-feet of Rocky Ford Highline Canal water annually, potentially drying up some 8,200 acres (approximately 36 percent of the total acreage irrigated by the canal), and allowing the city to refill drought-depleted reservoirs. Under the interruptible leasing approach, irrigators typically receive a one time sign-up fee and an annual payment per share of water, which provides stable income for farm-related investments, purchases, and debt repayment. Interruptible leasing also allows farmers or ranchers to maintain water for irrigation in most years, avoiding permanent dry-up of lands.

Assuming that irrigators dry up their least productive acreage, and more intensively farm their most productive land, this suggests it might be possible to transfer additional water from agricultural to municipal use, without a corresponding decrease in production. Although simpler with individual ditch companies, the concept might also work for a pooling arrangement of several ditches on a long-term basis, with selective fallowing or dry-up of some lands. These agreements could provide an annual supply for municipal growth, or periodic supply for drought.

More than half of Colorado's agricultural irrigation demand—some 2.0 million acre-feet—is in the South Platte and Arkansas River basins. Idling 15 percent of this acreage would supply nearly 300,000 acre-feet for Front Range municipal growth, roughly two-thirds of projected 2030 municipal and industrial demands. This illustrates the potential of agricultural to urban transfers to protect and enhance long-term agriculture and rural communities, while contributing water to meet municipal growth.

Water Conservation and Efficiency
Conservation strategies function in one of two ways: fundamentally reducing demand or stretching existing supplies. There are a variety of ways to accomplish this, including demand reduction, water reuse, re-operation of reservoir systems, and regional coordination.

Public values largely drive long-term demand. Water-dependent landscaping, including traditional grass, constitutes from a third to nearly two-thirds of Front Range municipal demand during the summer months. Changing values could reduce long-term demand and corresponding needs for additional water supply.

Reuse of trans-mountain return flows is another proven strategy. According to Colorado law, water imported into another river basin can be used and reused to extinction. Decades ago Colorado Springs pioneered a program that irrigates golf courses, cemeteries, public properties, and sports facilities with non-potable reused water. Aurora also has a reuse program, and, like Colorado Springs, plans expansion. Denver's reuse project came on line in 2004.

Coordinated operation of existing storage facilities owned by different entities is another conservation strategy. So-called reservoir ‘reoperation’ capitalizes on the increased flexibility available from operating several facilities as one to increase yields without building new structures. The potential of coordinated reservoir operations is evident from the 63,000 acre-feet delivered to support endangered fish in the Grand Valley in 1999. The U.S. Bureau of Reclamation is also examining the use of ‘excess’ capacity in the Fryingpan-Arkansas Project to store water for Aurora and others.

Regional coordination and cooperation is another proven strategy to meet future growth demands. Windy Gap Project upstream of Kremmling, and the Windy Gap Firming Project, involving potential construction of a new off-channel reservoir, are examples of multi-purpose projects that will help supply 11 Front Range municipalities with up to 48,000 acre-feet of additional water per year.

Water for Recreation and the Environment
More people means more demand not only for municipal water, but also for every use, including recreation and the environment. The Colorado Water Conservation Board continues to appropriate water for instream flows to preserve the natural environment to a reasonable degree. Others, such as the Colorado Water Trust, donate water to the CWCB for this purpose. Owners of water rights can also loan water to the CWCB for instream flows. Communities are also appropriating in-channel diversions to meet recreational demands.

Cooperation is another proven approach. An annual interagency agreement between the Fryingpan-Arkansas agencies and the Colorado Division ofWildlife ensures up to 400 cfs for the Browns Canyon stretch of the Arkansas River. A long-term agreement between Denver Water and the Farmers Reservoir and Irrigation Company provides 150 cfs of water to the South Platte River through Denver. On a longer-term basis, Eagle Park Reservoir provides water for instream flows, in addition to water for headwaters communities and ski areas. These examples are especially significant because they involve municipal suppliers addressing recreational and environmental needs.
Growth and drought place Colorado at a crossroads. New on-stream reservoirs, trans-mountain diversions, and transfers of water from agriculture are unlikely to meet the needs of Front Range growth due to opposition from basins where the water would originate and concerns over diminishing supplies for their own domestic, agricultural, recreational, and aquatic ecosystem needs.

However, moderate changes in historical water supply practices offer the possibility to better balance the environmental and social trade-offs required to support new growth. These strategies include small trans-mountain diversions that benefit both the basins-of-origin and the Front Range, reconceived agricultural to municipal transfers that provide water for growth and preserve water for irrigation, municipal demand reduction, more efficient use of existing water supply infrastructure, and projects that incorporate recreational and environmental flows.

Editor's Note: Peter Nichols currently practices law with the Denver firm of Trout, Witwer & Freeman P.C. He is the principal co-author of ‘Water and Growth in Colorado, A Review of Legal and Policy Issues’ published by the Natural Resources Law Center, University of Colorado School of Law (2001), and other articles on water issues.

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