courtesy of AgNews - CSU Agriculture News
What is drought?
The government officially defines drought as "a period of
insufficient rainfall for normal plant growth, which begins when
soil moisture is so diminished that vegetation roots cannot absorb
enough water to replace that lost by transpiration."
This is a good definition for areas that depend on rainfall for
their moisture, but, in Colorado, 80 percent of our surface water
supplies come from melting snowpack. A better definition of drought
for Colorado might read: "A period of insufficient snowpack
and reservoir storage to provide adequate water to urban and rural
What is snowpack?
Snowpack in Colorado refers to the accumulation of snow that gradually
adds up over the course of the winter, mostly in the mountains.
The water content of snowpack is what water officials monitor closely
because it directly relates to the amount of water that will end
up in Colorado's rivers, streams, reservoirs and irrigation canals
during the late spring and summer.
The water content in mountain snowpack normally reaches its greatest
amount in mid-April but sometimes does not peak until late April
or early May. Based on average measurements of more than 70 monitoring
locations in high and moderately high snow accumulation areas in
Colorado's mountains, the average snowpack water content is about
18 inches at its peak.
What is a river basin?
A river basin is simply the land area that could contribute water
to a particular river by natural gravity. The South Platte River
Basin, for example, consists of all the areas from the crest of
the mountains (the Continental Divide in this case) to the river
itself, where all water that flows naturally by gravity without
evaporating would end up in the South Platte River. Thus, Castle
Rock is in the South Platte River Basin as is Cheyenne, Wyoming
and Estes Park, as well as the cities of Denver, Greeley, Fort Morgan
and others that are immediately along the river.
What is stream flow and what does it measure?
Stream flow is the volume of water passing a specified point along
a river or stream. Stream flow is typically measured in units of
cubic feet per second to define instantaneous flow rates, or in
acre-feet to define the total volume of water over longer periods
Scientists have long established useful relationships between measured
snow pack levels and ensuing stream flow volumes so that winter
and spring snowpack measurements result in reasonably accurate predictions
of spring and summer stream flow from Colorado's mountain rivers
In Colorado's water law system, accurate measurements of stream
flow are critical for determining how much water is available to
each water owner. Hydrologists and engineers also track stream flow
carefully in order to determine how large to build structures such
as bridges, culverts, canals, dams and spillways to safely convey
water from snowmelt and from heavy rains.
How will this drought affect the average Colorado
The water shortage affects many industries, including farmers,
vegetable growers and greenhouses, as well as implications for individuals
in urban and rural areas and how they'll use water. Some water users
will be impacted more than others. For example, people who own land
with junior water rights will be impacted by the low snowpack and
runoff levels expected this summer.
Food producers, including farmers and ranchers, may be the most
affected by the drought, but urban water users also will experience
consequences. Water conservation is an important tool that can help
preserve water during a dry year. Some strategies that all citizens
can use to contribute to water conservation are to reduce their
personal water use at home and on their landscapes. For more information
about water conservation in the home and on landscapes, contact
the local Cooperative Extension office, usually listed under the
county government section of the local phone book. Information also
is available at www.agnews.colostate.edu and will continue to be
updated throughout the summer