The Western United States has long considered its mountains, a hedge against drought and water shortage. Yet citizens in these areas are faced with accepting a new moisture norm. Many western communities have seen water supplies shrink, temperatures rise and precipitation patterns shift. The notion of Climate Change has become more palatable as the consequences of these changes have become apparent. A rise in severe weather along with changes in the timing and location of precipitation have made even staunch doubters wonder.
These shifting precipitation patterns are benefiting some regions with additional water, while reducing snow and rainfall in other areas. Southwestern states are experiencing the greatest decline in precipitation. While western snowmelt-dominated watersheds have been hit hard. Rising temperatures causes more precipitation to fall as rain rather than snow and which melts mountain snowpack earlier in the season, reducing the natural reservoir that has traditionally fed western rivers throughout drier summer months.
Across the country, warmer temperatures also increase evaporation from reservoirs and lakes, counteracting increases in precipitation in some regions and amplifying decreases in western areas. The ability of the Atmosphere to hold moisture increases exponentially as the temperature rises, leading to a greater capacity for heavy precipitation events and floods. Nationwide, the number of storms with extreme precipitation has increased 24 percent since 1948. This trend is expected to continue in the future. The resulting floods will claim lives and destroy property, especially in communities built in floodplains. While the expanding drought areas decrease water in our agricultural basins.
The federal Bureau of Reclamation, which manages much water in the West, reported in 2013 that average temperatures in the upper Rio Grande, in Colorado and New Mexico, rose almost 2.8 degrees during the 40 years ending in 2011 — and could rise an additional four to six degrees by 2100. (Marcott et al. 2013) This 40-year increase is twice the global average and is beyond anything seen in the last 11,300 years. Future warming “has the potential to cause significant environmental harm and change the region’s hydrology,” according to the repot. (West-Wide Climate Risk Assessment: Upper Rio Grande Impact Assessment, US Bureau of Reclamation Dec.2013)
In addition to shifting average temperatures, the increase in weather extremes is a serious threat to water supply. Precipitation is becoming more variable and more uncertain, leading to more frequent and more intense floods and droughts.
The bottom line is that in the Upper Rio Grande Basin the water management challenges presented by a variable and exceptionally limited water supply have been intensified by sustained drought. Water managers have had to consider if the hot and dry conditions experienced in the Upper Rio Grande Basin in the past several years are connected to climate change, and if they are how should water management planning should include the possibility of a hotter, drier, and more variable future.
Projections regarding the future of the Upper Rio Grande show changing hydrology that has significant implications for water management, human infrastructure, and ecosystems. Although there are uncertainties in the details, current observations seem to present some alarming trends.
- Decreases in overall water availability. Supplies of all native sources to the Rio Grande are projected to decrease on average by about one third.
- Changes in the timing of flows. The anticipated changes mean the extension of changes that we are already experiencing. Such as, earlier snowmelt runoffs that include increased variability in the magnitude, timing, and distribution of streamflow’s. This indicates basin wide decreases in summertime flows and lesser decrease (or potentially even an increase) in wintertime flows.
- Increases in the variability of flows, which means substantial variability in the month-to-month and inter-annual variability of flows through the remainder of the century. Specifically, the frequency, intensity, and duration of both droughts and floods are projected to increase.
The consequences of these shifting weather patterns depends in large part upon choices that communities have made in the past and are making now. These choices hinge upon the quality of natural infrastructure – forests, watersheds, wetlands, streams and rivers – that have fewer defenses as the landscape dries out. The quality of these natural structures is directly tied to manmade infrastructure such as dams, reservoirs, ditches and wells. The tough part is that our economy and way of life are indelibly tied to the harmonious interaction of the two.
Enter the Rio Grande Basin and Colorado Water Plans. These plans offers a strategic vision: a productive economy that supports sustainable communities, productive and sustainable agriculture, a strong environment, and a resilient recreation industry. The Rio Grande Basin Plan outlines the strategies, policies, and actions by which the Rio Grande Basin can address its proposed future needs in a manner consistent with this vision. This plan, is the first of its kind for the Rio Grande Basin and Colorado and was achieved through the collaboration of the Rio Grande Basin roundtable, local governments, water providers, and other stakeholders. Both plans represent a set of collaboratively developed guidelines and actions that all Rio Grande Basin residents and Coloradans can support and to which they can move forward with better understanding of the challenges and opportunities that lie ahead.
The Rio Grande Basin, along with the other eight basins, are in the process of finalizing their Basin plans. The Colorado Water Plan (CWP) is wrapping up the public comment period for the first draft. The comments will them be reviewed and assimilated into the second draft which is expected out by July 15, 2015. The review and comment process will begin immediately upon release of the second draft CWP and that comment period will close September 17, 2015. To review the Rio Grande Basin Plan go to www.riograndewaterplan.com or to review the Colorado Water Plan go to www.coloradowaterplan.com.