Watering the West: Growth Stops When the Water Runs Out

A recent issue of National Geographic featured a compelling story on the double-barreled threat facing western states: rapid population growth and climate change. "The American West was won by water management," proclaims the article. "What happens when there's no water left to manage?"

This question vexes more than water managers. It may seem absurd to approve development without reliable water supplies, but that is exactly what has happened in many communities -- leaving homeowners and other taxpayers holding the bill when extravagant measures become necessary to gain access to water.

Just as homeowners demand, and building codes require, safe wiring and solid foundations for their dwellings, they also deserve to know that their drinking water taps will deliver clean, reliable water for decades to come. Moreover, states are currently reckoning with the question of what happens when there is little water left to manage -- two weeks ago, California Governor Arnold Schwarzenegger declared a statewide drought.

Historically, land-use decisions and water planning have been treated as entirely separate issues. Water is allocated by state agencies, and land-use planning falls under the authority of local officials. Water resource managers juggle many competing demands within a watershed, and they tend to focus on facilitating economic development. In turn, local land-use authorities have safely assumed that water would be available to satisfy continued growth.

Increasingly, however, local land-use decisions run headlong into water supply concerns. Planning for growth is important in all communities, and planning for sustainable water supplies to support that growth should be an integral part of that planning process. Although water itself seldom provides a hard barrier to growth, the failure to connect land-use and water planning may have far-reaching and increasingly unacceptable consequences.

In some cases, existing uses are depleting finite water supplies, raising questions about their future reliability. For example, in some fast-growing rural areas of Arizona, recently constructed houses draw water from wells that the state engineer's office has certified as "not reliable" due to insufficient underground supplies. Some new homeowners did not realize the tenuous nature of their water supplies and have been forced to deepen their wells or construct cisterns and pay for trucked-in water.

Elsewhere, officials are beginning to face the high social, environmental, and economic costs of obtaining water to meet rising urban demands. Urban growth around Phoenix, Denver, and Boise has been fueled by voluntary, market-based reallocation of water from farms to cities. But public outcry over Las Vegas' long reach into rural Nevada may indicate renewed concerns over the impacts of large-scale water transfers, both on the rural communities from which the water is taken and on the pocketbooks of the consumers receiving it.

With the recently enacted H.B. 1141, the Colorado General Assembly took an important first step in ensuring such reliable water supplies for new development. This law creates a new tool for local governments to determine whether development projects can demonstrate that the proposed water supply is adequate to meet the project's water supply demands. It gives local governments the authority to deny developments without adequate water supplies, but the local governments retain discretion to decide whether to authorize development.

In addition to the steps prescribed by the Colorado legislature, a number of other policy levers could be employed to provide a better handle for water-conscious land use decisions. The Colorado bill does not, for example, assign any time horizon to the supply requirement, but simply looks at the possible peak daily, monthly and yearly demands at projected build-out levels of development. Other states, including Arizona and California, require such "assured supplies" for 50- to 100-year planning horizons, although each state has significant exceptions built into the requirements.