Chasing Snowflakes

By: Andie Hall

It’s not rocket science to understand Colorado relies on a steady water supply; it’s snow science. Most of Colorado is in either extreme or exceptional drought, the two highest possible rankings on the United States Drought Monitor. This drought is driving Colorado to focus on better understanding water content in the natural reservoirs of the snow pack. Snow is a less direct water source than rain because it sits longer where it falls, unless the wind picks it up and moves it. Rain, on the other hand, falls and flows much more directly by infiltrating into the groundwater table, percolating into a stream, or directly as surface runoff. The characteristics of snow make it difficult to measure, but quantification is needed for water supply planning.

For water planning purposes, snow is measured in Snow Water Equivalent, “SWE,” which translates to the amount of water contained in the snow. Having a quantifiable amount of water in the winter allows for spring and summer water supply planning, and is especially important during drought. As water supplies become more stressed in extreme drought, it is increasingly important to have accurate SWE measurements. To try to get a better idea of a substance that doesn’t fall uniformly across the landscape, researchers have created an airborne observatory that utilizes lidar to measure SWE and albedo in the snowpack.

Using these new technologies, researchers have been able to forecast future snow pack with more accuracy. Unfortunately, the forecast projects increased frequency of “snow droughts” across the west. Being aware of what the future holds is necessary for water suppliers, like Denver Water, to plan accordingly for shortages. That’s why a group of water providers created a council to fund cloud seeding programs. Cloud seeding is a weather modification technique used to increase snowfall. Silver iodide is burned through an ice nucleus generator and carried into the atmosphere to the clouds to stimulate precipitation. Weather modification has taken place in Colorado since the 1950s, but cloud seeding has gained recent importance in light of the current drought.

One of the biggest advancements is remote controlled seeding generators, which can be placed at higher elevations because humans don’t need to frequent them to ignite the process. The State Department of Natural resources has seven cloud seeding programs across the state that are funded by over forty organizations. The Council and other entities fund the operation and maintenance of cloud seeding equipment.

Cloud seeding requires specific climatic conditions in order to be effective. Surprisingly, it doesn’t make clouds. Rather, cloud seeding enables existing storms to produce more snow. Under the right conditions, cloud seeding can increase snowfall by five to fifteen percent. In these conditions, there is the possibility of an additional 60,000 acre feet of water added to the resource-strained Upper Colorado River Basin.

Front range cities like Denver and Aurora depend on a steady snowfall for water supply from regions like the Colorado River Basin. Likewise, ski resorts depend on snowfall for a successful and profitable season. That’s why entities like Vail Resorts invested in the cloud seeding programs in Colorado. Vail has invested in weather modification for forty-four years and its funding program produces about half of the seeded snow in the state. This year, due to budgetary constraints, Vail suspended cloud seeding funding. This will undoubtedly create new challenges for water managers and the state in water supply planning. There will likely be impacts across the water sheds where Vail’s cloudseeding has previously supported the water supply. Many junior water rights holders are unlikely receive their allocations if the drought patterns continue. Could they hold Vail liable for these losses because these water users have become reliant on them for so long? The legislature and the courts will not be able to force Vail to participate, but the Colorado water community certainly emphasizes collaboration, especially in times of drought. However, because it is so early in the season, some optimism remains that this winter will bring enough natural snowfall to make up for the seeding loss.