The CWCB administers Colorado’s Weather Modification (WM) Program, which issues WM permits, monitors WM activities and keeps the public informed about the state’s WM activities. Colorado has conducted weather modification operations and research since the 1950s, and a program to permit weather modification has existed since 1972. After the significant drought starting in early 2000, many new WM permits have been developed. Colorado is a strategic state with the headwaters of eight major river basins, and downstream states are reliant on the snowpack and stream flow generated in Colorado.
New rules are in effect as of July 1, 2012. The rules are listed under Additional Information.
What Is Weather Modification?
Cloud seeding is the primary weather modification activity recognized by the State of Colorado. Cloud seeding
is the process of burning silver iodide through an ice nucleus generator that is carried up into the clouds to stimulate the precipitation process. There are many types of weather modification, including ground-based snowpack augmentation, airplane-based snowpack augmentation, airplane rain augmentation, hail suppression and hail cannons.
Colorado’s Permitted WM Projects
A permit is required to modify the weather in Colorado. See the Permit Program
page for more information about applying for a weather modification permit and the permitting process.
Most of the permitted projects in Colorado are based around ground-based operations with the goal of snowpack augmentation. There also are permits in Weld County and the San Luis Valley for hail cannons for suppression, which uses sound cannons to disrupt cloud processes. More information is available on the Permit Areas
Suspension of Cloud Seeding Activities
The CWCB staff monitors snowpack, avalanche hazards, and other environmental conditions during winter. Using data from the Colorado Avalanche Information Center
and NRCS Snow Survey Program
maps, the CWCB will temporarily suspend or curtail cloud seeding activity in areas with high snowpack and high avalanche hazard levels when warranted. The additional snowpack is good for Colorado but thresholds are set on snow water equivalent to ensure that snowpack in a watershed stays within the realm of natural variability for the local climate. The triggers for snowpack are when snow readings at NRCS SNOTEL sites are at the high end of the 30-year average for that SNOTEL site.
Weather Modification Grants
The CWCB provides state grants to water providers and local governments to assist in funding ground-based wintertime operational cloud seeding programs. Weather modification programs like summertime hail cannons or aerial hail suppression and rain augmentation programs are currently not eligible for grants. More information is available on the wintertime Weather Modification Grants
In addition to CWCB resources, there is also regional funding that is leveraged for locally sponsored programs. Shortages in the Colorado River Basin and low levels at Lake Powell and Lake Meade led to meetings among the seven states along the Colorado River. The result was several agreements among the states to work collaboratively to resolve issues. One of those agreements was to pursue wintertime cloud seeding in the Upper Basin States of Colorado, Wyoming and Utah. Colorado’s agreement is between the CWCB and the Southern Nevada Water Authority, Central Arizona Water Conservation District and the California Six Agency Committee. Every year, agreements can be signed that provide funding to extend the length of time of operations, provide new equipment and conduct studies and evaluations.
The CWCB also has a similar agreement with the New Mexico Interstate Stream Commission to provide funding to programs in southwestern Colorado. The CWCB seeks to ensure there is an equitable division of resources and that well-designed and executed programs are operating in Colorado.