BOARD01283

• Board Meeting Date: 9/24/2001
• Description: Flood Section - Added Agenda Item: Drought Planning Survey Carryover Assessment Project
• Board Meetings - Doc Type: Memo

II. Backl!:round
Drought is a naturally occurring part of the clim:j.tic cycle in Colorado, Our unique topography and
geography contribute to variations in annual precipitation from seven inches to over fifty inches within a ...
linear range of about two hundred miles, The average precipitation along the Front Range, where the ..
majority of the state's population resides, is about sever)teen inches, The accurate prediction oflong-term
drought remains an elusive process, although improverJents are occurring with technological research and
communication advances. Our state's brief recorded hi~tory does indicate five dry periods in a range of
two to twelve years in duration since 1893, The last prQlonged drought period was from 1951 to 1957.
Currently, the state is in a prolonged wet perio~ that began in 1981, however, there have been short
term, regional dry situations around the state during tru;s time, hnpacts from drought have been regionally
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severe in 1976-77, 1980-81, 1989-90,1994, 1996,2009, and 2001. Due to the variability of climate it
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would be unusual, but not impossible, for the entire st~te to be in a long-term drought. Typically the
eastern plains, westem Colorado and the southwestern! Colorado are drought risk areas,
Colorado's water comes from various forms of precipitation, The vast majority of our state's water
comes from snowpack supplemented by rain events, ~nowmelt is either stored in reservoirs or diverted
from rivers and streams, Colorado droughts can be frdm either a lack of rain and/or a lack of snowpack in
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the mountains. Groundwater is also an important watllr source for residential and agricultural use
particularly in rural areas. e

What is a droul!:ht
A drought is a condition of abnormally dry weather within a geographic region where some rain
might usually be expected, A drought is different from a dry climate, which designates a region that is e
normally, or at least seasonally, dry, A drought typically c,an last from two years to several decades, The
severity ofthe drought is gauged by the degree of moisture deficiency, its duration, and the size of the area
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affected, Catastrophic droughts generally occur at latitudes of about 150_200, (Colorado is between 370-
410 north latitude) in areas bordering the permanently arid regions of the world, Severe but not
catastrophic drought have occurred relatively often in the United States, The statistics indicate that
roughly every 22 years a major drought occurs in the United States, most seriously affecting the Prairie
and mid-western states, Although drought cannot be reli~bly predicted, certain precautions can be taken in
drought-risk areas, These include construction of reserv6irs to hold emergency water supplies, education
and water conservation programs,

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