The study’s first task was to identify municipal demand, and in doing so, the analysis provided population projection ranges for Archuleta County. Using a variety of sources, the ranges project that, in 2050, the population could be at 16,623 (low), 21,652 (medium) or 24,979 (high). In 2050, these ranges put municipal water demand at 4,208 acre-feet (low), 5,481 acre-feet (medium) or 6,323 acre-feet, calculated using a constant of 226 gallons per capita per day, which reflects the current demand.
[Wilson Water Group] also calculated demand needs in agriculture, environmental and recreation, using a variety of sources and data. Cumulatively, all of these demands (including municipal needs) were used to calculate different shortage scenarios and, ultimately, explore solutions for meeting these potential shortages. This included calculating potential reservoir sizes, which was met with contention at the event. The limiting factors in reservoir sizing are the legally and physically available water to fill the reservoir, the 50 cubic feet per second (cfs) filling constraint, and the demands driving reservoir releases, the analysis explains. The 50 cfs limit is based on the Dry Gulch Reservoir water right, and that the Dry Gulch environmental flow stipulations had to be met when the reservoir was filling, [Erin] Wilson explained…The recommendations for the reservoir size were 1,600 acre- feet to meet low demand and 10,000 acre-feet to meet mid-range demand. Wilson clarified these calculations are usable volume numbers, not the total volume of the reservoir…
Other highlights of the report include:
• Municipal water demands could more than double if the pace of population growth in Pagosa Area Water and Sanitation District’s area continues at current rates.
• Under historical climate conditions, agricultural demands are not expected to increase and may actually decrease due to urbanization.
• The two largest concerns affecting current and future water uses are earlier runoff and the potential for a catastrophic fire. Having storage to help capture earlier runoff could continue to be important in the future, and additional storage could provide redundancy and help mitigate the effects of a fire.
• Other alternatives, including stream restoration, fallowing and forest health, have the potential to improve streamflow and the SJWCD should continue to monitor on-going projects to see how the results could be applicable in the Upper San Juan Basin.
The public comment period is open until Aug. 31. Comments can be sent to comment.sjwcd@ gmail.com.