Colorado water managers plan for climate change

What do we know about climate change and the effects on Colorado's future water supplies? Actually that's a trick question. We cannot know with anything with certainty because climate is just too complex. Water managers around the state are focused on planning for the future. That's the nature of their job. For most, the planning has included an analysis of past precipitation and runoff statistics paired with forecasts for population and other uses. Precipitation, runoff dates and stream flow are measurable with pretty good accuracy. According to dictionary.com a synonym for forecast is prescience or the ability to predict the future so there is much uncertainty in climate science. However on a macro scale trends can be identified from models.

Climate scientists know this and continually measure their models against past and current data. They've predicted many of the events we are currently witnessing, including the melting at the poles. They're the first to concede that the models cannot forecast specifics, just trends.

Back to Colorado water supplies and climate change.

I read a great book last fall Six Degrees: Our Future on a Hotter Planet. I was captivated by the section of the book that dealt with the southwestern U.S. The author, Mark Lynas, used the fall of the Native Puebloan culture in and around Mesa Verde to tell the story of a 1 degree celsius rise in global average temperature. Most Coloradans are familiar with the story. The Native Puebloans left the area after a period of time where they abandoned their farms in lower areas and moved up to the mesa tops and along the canyons, both for better water sources and defense.

We are already past the threshold where greenhouse gases will cause the 1 degree celsius rise in the global average temperature so Colorado water managers can look at the fossil and achaeological record from 1200 - 1350 A.D. for trends in water supply. Lynas documents the evidence of extended drought in the Colorado River Basin, some as long a 50 years. The Sand Hills of Nebraska were around at that time. From the Wikipedia entry, "At several times in the past 10,000 years, during periods of extreme drought, the Sand Hills have been active sand dunes; however, this has not happened since around 1400 A.D."

So what can we expect from climate change (with high probability)?

Colorado will likely see longer and more intense droughts. While much of this will occur in the Colorado River Basin it will effect the eastern part of the state since most municipalities there depend on transmountain or transbasin diverions.

Some pests will prosper with warmer temperatures. The pine beetle destruction up in Grand County is an example. Drought and warm temperatures fueled beetle kill a few years ago, in and around Montezuma County, which led to the loss of much of the piñon tree canopy.

Runoff will occur earlier in the year along with higher losses from sublimation [pdf]. Bottom line: The snowpack may be gone before it's needed or stored.

More precipitation will fall as rain rather than snow. For the last couple of years the North American Monsoon has brought needed water to Colorado, New Mexico and Arizona. Some predict a strengthening of the monsoon with climate change.

So what are Colorado water managers planning?

Storage is #1 on the minds of most water providers. The Northern Integrated Supply Project has been in the news a lot lately, owing to the release of the draft environmental impact statement. The centerpiece of the project is Glade Reservoir, off the main stem of the Poudre, to be filled during years of plentiful runoff and by transfers of agricultural water. Another Front Range reservoir in the planning stage is Chimney Hollow. There are projects on the drawing board to expand Lake Pueblo and Clear Creek Reservoir along the Arkansas River. Pagosa Springs is breaking the backs of their rate payers buying land and water for their proposed Dry Gulch Reservoir. Old Lake Dillon is getting a face lift and Denver Water is looking at expanding Gross Reservoir. There are many other projects but you get the idea. In the last two years the Colorado Water Conservation Board has funded and encouraged studies of the potential of using groundwater recharge for new storage.

The unbridled growth along the Front Range keeps managers looking at new water supplies from the West Slope. The proposed Yampa Straw would move water from a new reservoir near Maybell through a new pipeline to the dry side of Colorado. An entrepreneur, Aaron Million, hopes to get water and permits to build a privately financed pipeline from Flaming Gorge Reservoir to northern Colorado and points south. Colorado Springs is proposing their Southern Delivery System to develop their water rights and meet their growth needs. This project also includes two new reservoirs in the Fountain Creek drainage.

I've sort of beaten the conservation drum enough in this space. However, conservation is a huge piece of the puzzle for water managers. Denver, Fort Collins, Boulder, and most cities on the eastern plains have active conservation programs in place. Denver Water's Sara Duncan says that the utility is attempting to, "grow supplies from what we already have," using conservation and reuse. Output from the DWD reuse plant will double in 10 years. Aurora is going to introduce reclaimed water into their drinking water system when their "Prairie Waters Project," comes on line.