WSP06278

• File Number: 8040.970
• Description: Drought Preparedness
• State: CO
• Basin: Statewide
• Date: 6/1/2002
• Author: USDA
• Title: Colorado Basin Outlook Report
• Water Supply Pro - Doc Type: Report/Study

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COLORADO
WATER SUPPLY OUTLOOK REPORT
June 1, 2002

Summary

Water year 2002 will be one for the books for some time to come. Oue of the lowest
snowpack accumulations in decades, followed by one of the driest springs in many years, all
on the heels of several previous dry years, contributing to below average reservoir storage and
dry soils. With all these critical elements in place, the state has the ingredients for a water-
short year unseen by most of it's residence. This summer's monsoon moisture can help reduce
short-term needs, but the state will need an above average snowpack year in 2003 to recover
from these deficits.

Snowpack

Warm and dry weather allowed snowmelt to proceed unabated throughout the month of May."
By the end of the month, only two out of the state's 86. SNOTEL sites had any snow
remaining~ This left the state with a statewide snowpack of only 2% of average and 10% of
last year's totals on this date. The snowpack across most of the state had melted out during the
later half of May. This leaves only the Yampa and White, and North and South Platte basins
with any snowpack remaining. As a percent of average, they range from 15% in the North
Platte Basin, to only 1 % of average in the South Platte Basin. A1> a rule, the state's basins
melted out about two months earlier than normal this spring. In many parts of the state this
meager snowpack was sitting on very dry soils. As melting began, much of this moisture
simply soaked into the ground, before ever making it to the streams. Snowmelt during the
month was also hampered by many windy days with low humidities. these conditions can
result in a substantial loss of water to sublimation. In a dry year like this, these losses can: be
significant for many water users. Based on April 1 data, 2002 will be the 5th consecutive year
with a below average statewide snowpack.

Precipitation

Precipitation at Colorado's SNOTEL sites was well below average across the state during
May. This marks the ninth consecutive month with below average SNOTEL precipitation.
May's statewide totals were only 34% of average. These low percentages helped to decrease
the statewide water year (since October 1, 2002) percentage to only 56% of average.
Southwestern Colorado continued to report the lowe,st accumulations in May. Monthly totals
in the Rio Grande and combined San Juan, Animas, Dolores, and San Miguel basins were
only 16% and 10% of average, respectively. The Gunnison Basin only fared slightly better at

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