What is Drought?

City Council adopted the Water Supply and Demand Management Policy (PDF 185KB) in September of 2003. (Detailed report available - 111 page PDF 3.8MB) The policy states, "The reliability of the Fort Collins water supply should be maintained to meet at least the 1-in-50 drought event in the Cache la Poudre River Basin."

Fort Collins Utilities defines a drought as below-average runoff from the Cache la Poudre River. Droughts are measured by:

• duration (or run length),
• cumulative deficit below the average, and
• average annual water shortage.

Through statistical analysis, City officials determined the worst drought that could occur every 50 years in the region. This "design drought":

• lasts six years;
• has a run-off that's 550,000 acre-feet below average; and
• has annual river volumes about 70% of the Poudre River's long-term average.

Utilities staff use this design drought to determine Fort Collins' current and future water supply needs.

Fort Collins Drought History

The graph below shows annual virgin (or native) flows of the Poudre River since 1884. Flows vary significantly from year to year. The green line on the graph denotes the long-term average.