ditches in pipe” to cut evaporation and farmers who flood irrigated for years are now trying sprinklers and drip irrigation. What Catlin observed parallels what Stratus’ Smith and others have already discovered. “The availability of water is shifting,” said Smith. Anecdotal evidence is abundant on the state’s river systems, but except for the Colorado River, extensive scientific information about climate change effects is slim. As a state, Colorado does have a couple advantages: a well-established water appropriation system and experienced
researchers say the West is warming at twice as fast as the global rate. What does that mean for Colorado’s other rivers? So far, climate researchers are not investigating Colorado’s other major rivers—the South Platte, Arkansas and Rio Grande. Denver Water has conducted some “crude” modeling on its water supply. With a 2 degree Fahrenheit increase the model showed a 7 percent decline in supply. With 5 degrees, the decline doubled to 14 percent. “We know we’re vulnerable to temperature changes,” said Marc Waage, Denver Water’s manager of water re-
The group plans to develop two hydrological models, Waage said, so researchers can compare variations. The project, conducted by consultants in collaboration with the ninemember group, is expected to take about a year. “As far as I know this is the first region in the U.S. to do this,” Waage said. One component of the project is to standardize scenarios through the models so water managers are all “on the same page.” The CWCB, he said, wants to learn whether hydrology models can be developed regionally, which would be more economical. The models un-
water managers. “Prior appropriation has kept the rivers alive,” Catlin said. And the knowledge water managers have about how to respond to supply fluctuations puts them in a position to deal with changes on the short and long term. But eventually, they’re going to need more. The Colorado River, on which an estimated 30 million people depend, is under intense study to forecast hydrologic and climate change effects. In 2006, the U.S. Bureau of Reclamation brought together a group of scientists. The results, “The Climate Technical Group Report,“ found detailed information is necessary to improve Reclamation’s “decision support framework,” which includes climate modeling and applying the data. The report is an appendix to the final Environmental Impact Statement for operating guidelines in the Colorado River’s Lower Basin. Other
source planners. “We need new models. We have a range of projections to look at, but no real agreement. Denver Water initiated a Front Range hydrology project to collect climate change information and adapt it to determine what the effects on water supply might be. Denver Water; the Northern Colorado Water Conservancy District; Colorado Water Conservation Board; the Water Research Foundation, formerly the American Water Works Association Research Foundation; the Western Water Assessment; and the cities of Aurora, Boulder, Colorado Springs and Fort Collins are collaborators on a Front Range hydrology project intended to determine the possible effects of climate change projections on streamflow. First, though, there’s one big hurdle: The models illustrate climate change scenarios, but “they don’t have a model to convert (that) data to projected streamflow changes,” said Waage.
der development will “have a range of projects to look at.” When the results are in, said Waage, the participants can plug the data into their own allocation models. “Once we have a model, we can plug information into a water allocation model and then into water rights.” Then water managers will face the task of incorporating “deep uncertainty into water planning.” Denver Water and others have taken pages from the oil and financial companies to learn how to weave a water resource plan from multiple sources of information and possibilities. That means revamping the way water planning has been done in the past. Still, climate change research competes for money with water managers’ day-to-day concerns, such as water quality and how to balance growth and resources. The key, Waage said, is to “keep options open and build in flexibility. Hydrology models are the key step.” q
Citizen’s Guide to Colorado Climate Change