Climate change could make state more vulnerable to dry spells
By Summit Voice
SUMMIT COUNTY — Colorado’s recently completed drought response plan considers impacts like crop and livestock losses, insect and pest issues and even things like the cost of highway closures from blowing dust.
The plan outlines factors like big snowpack deficits during the ski season and reduced streamflows reservoir levels in key fishing and boating areas, as well as high wildfire danger that could result in forest closures — all amounting to significant economic impacts for the state through reduced visitation, a loss of sales tax revenues and cuts in employment in various economic sectors affected by drought.
According to the executive summary, the plan outlines a mechanism for coordinated drought monitoring, impact assessment, response to emergency drought problems, and mitigation of long term drought impacts. There are three major components of the plan: mitigation, response and vulnerability assessment. Click here for links to all documents relating to the drought response plan.
One task force would assess impacts to Colorado wildlife and recommend mitigation and response actions. The impact assessment would include:
- Wildlife losses on DOW-controlled properties and public lands such as fish hatcheries, reservoirs, streams, terrestrial wildlife habitats, and associated recreational areas.
- Estimate potential short-term wildlife losses and long-term projections for losses over the assessment periods.
- Evaluate impact on DOW-held water rights on reservoirs, streams, hatcheries, etc. Assess impacts to fish/fishery resources for threatened and endangered and priority species, including streams/lakes/reservoirs with potential for significant fish mortality and/or areas where angling restrictions might be necessary.
- Assess overall health condition and distribution of key game species and populations.
- Assess condition of critical winter ranges for key game species including identification of areas with new or expanding weed infestations.
- Assess impacts to bird production, nesting success, and brood rearing for upland game birds and waterfowl species.
- Assess impacts to water levels and wetland dependent vegetation for priority wetlands and riparian corridors.
- Identify wildfires and/or areas with drought-related forest health issues that have potential for direct or indirect impacts to wildlife.
- Economic impacts from wildlife including loss of revenue from decrease fishing and hunting license sales, water rights transfers.
Colorado has experienced several serious droughts since the state was settled in the late 1880s. The most serious droughts came in the 1930s dustbowl era, and again in the 1950s, when another multi-year dry spell hit the state.
Adding up all the dry years, state water planners say that, simply put, there’s about a one-in-three chance of experiencing drought conditions in any given year. — and climate change is expected to increase the frequency and severity of drought events, according to state water planners.
Here’s an excerpt on potential climate change impacts, taken from an earlier draft version of the plan:
• “Warmer temperatures will likely result in precipitation occurring as rain rather than snow, an earlier spring melt, more intense precipitation events, and increased evapotranspiration (CWCB 2008, CWCB 2010, Knowles et al 2006, Mote 2006, Saunders 2005, Udall 2007). . Consequently, runoff will start earlier and end earlier. Reservoirs will fill earlier, and what cannot be stored in the spring and early summer will be spilled when agricultural demands are not as great as they are later in the summer. Decreased runoff in the summer will result in additional reservoir drawdown and many studies agree that higher temperatures and lower precipitation during summer months will further increase agricultural demands, thus causing even more stress on reservoir storage (CWCB 2008, CWCB 2010).”
One of the most interesting chapters in the draft plan is the history of droughts in Colorado. The dust bowl drought came in three waves: 1934, 1936 and 1939-1940. The last of those droughts saw excessive heat even into the high country, with many July all-time high temperature records in Frisco set in the summer of 1939.
The 1950s drought hit the Great Plains and the Southwest especially hard, with a string of five dry years. Part of that time, drought stretched nearly from coast to coast. By the time the dry spell ended in 1957, many counties in the hardest-hit areas had been declared federal disaster zones.
The next major drought came in 1976-1977, when two-thirds of the state’s streams set all-time record low streamflows that held until 2002. The 1970s drought also gave ski areas the impetus to start thinking about making their own snow, a move that was reinforced a few years later during the short but intense drought that started in the fall of 1980 and continued to the spring of 1981. The early 1980s drought also triggered formulation of the state’s first formal drought response plan.
The state’s worst drought on record was in 2002, when the Rio Grande nearly ceased flowing. Based on tree-ring studies, the 2002 event may have been the worst-ever dry spell in Colorado. If global warming causes recurrences of 2002 conditions, it could stretch the state’s water resources close to the breaking point — hence the need for an up-to-date response plan.
The draft plan goes on to rank counties based on their susceptibility to drought in different sectors, including agriculture, recreation and energy, as well as important aquatic habitat.