Drought Basics

Drought Basics

Below are several common questions regarding Drought in Colorado. If you can't find an answer below, feel free to submit questions and comments on Twitter to @CO_H20 or email drought@state.co.us.

 

What is drought?

Drought is a normal, recurrent feature of Colorado’s climate but without adequate mitigation and response, it can be very destructive. Drought is a shortage of water associated with a lack of precipitation. It occurs when a normal amount of moisture is unavailable to satisfy an area’s usual water consumption. Drought can appear slowly and last for many years or it can be a short-lived event. It also can occur locally, regionally or statewide. Drought’s impact on society results from the interplay between a natural event, demands for water supply and the economic and environmental impacts that can result.

How is drought classified?

The United States Drought Monitor map, updated for the country every Thursday, identifies areas experiencing drought and labels them by intensity. D1 is the least intense level and D4 the most intense. Drought is defined as a moisture deficit bad enough to have social, environmental or economic effects

D0 areas are not in drought, but are experiencing abnormally dry conditions that could turn into drought or are recovering from drought but are not yet back to normal.

Chart of US Drought Monitor Categories with descriptions and numerical ranges

 

 

 

 

 

 

 

 

 

 

 

 

What is a drought declaration?

Drought declarations are traditionally made by public officials and may be made at the local, state and federal level. In Colorado, the Water Availability Task Force is responsible for assessing drought conditions and recommends to the governor when an official drought declaration should be made. Water providers can also officially declare a drought. Water restrictions and other drought response measures may be enforced following local drought declarations.

How does drought impact Colorado?

Drought is a prevalent natural phenomenon in Colorado. Single season droughts over some portion of the State are extremely common. Prolonged periods of drought develop slowly over several years and are cyclical in nature. With Colorado’s semiarid climate, there will always be a concern for water availability within the State.

There are many visual resources to help answer this question.

  • These new (May 2020) Storymap case studies review how drought impacts Colroado's outdoor recreation and agriculture industries.
  • The new (May 2020) Future Avoided Cost Explorer quantifies direct impacts of current and future droughts on select sectors of the Colorado economy.
  • The Drought Vulnerability Tool (March 2019) at the bottom of this page takes users through visual summaries of Colorado drought risk by sectors, based on Colorado’s 2018 Drought Plan
Does Colorado have a plan?

Yes! An advanced plan! The Colorado Drought Mitigation & Response Plan (2018) provides an effective means for the State to reduce the impacts of water shortages over the short and long term. The Plan outlines procedures for coordinated drought monitoring, impact assessment, response to emergency drought problems, and mitigation of long term drought impacts. There are three major components of the plan: mitigation, response and vulnerability assessments.

Full Plan (all appendices & annexes ~45 MB)

Am I required to have a state-approved Drought Mitigation Plan?

No, currently there is no statutory requirement that any entity have a State-approved Drought Mitigation Plan. However, the CWCB strongly recommends that water providers and state and local governmental entities develop a plan. Drought mitigation planning is critical to preserving essential public services and minimizing the adverse effects of a water supply emergency on public health and safety, economic activity, environmental resources and individual lifestyles.

What is the difference between Drought Mitigation Planning and Water Efficiency Planning?

It is common to confuse drought mitigation planning and water efficiency planning.

  • The goal of drought mitigation planning is to ensure an uninterrupted supply of water in an amount sufficient to satisfy essential needs. Drought response measures can include mandatory restrictions on certain water uses, water allocation or the temporary use of an alternative water supply. These measures are intended to be temporary responses to water supply shortages.
  • The goal of water efficiency planning is to achieve lasting, long-term improvements in water use efficiency. Water efficient measures can include managing landscape irrigation, implementing efficiency based water rate structures, replacing or retrofitting water fixtures and similar efforts.
How much rainfall does Colorado receive annually?

Annual precipitation in Colorado averages only 17 inches statewide, with the majority of the State receiving only 12 – 16 inches.

How often does drought occur?

Historical analysis of precipitation and other drought indices show that drought is a frequent occurrence in Colorado. Short duration drought as defined by the three-month Standardized Precipitation Index (SPI) occur somewhere in Colorado in nearly nine out of every ten years. However, severe, widespread multiyear droughts are much less common. Since the 1893, Colorado has experienced six droughts that are widely considered “severe.” These droughts affected most of the state, involved record-breaking dry spells, and/or lasted for multiple years.

What are drought triggers?

A drought trigger is the specific value of a drought indicator that activates a management response. For example, a drought trigger could be a reservoir decreasing below 50% of its storage capacity. In a drought contingency plan, trigger levels can be varied to alter the sensitivity of the response and the effectiveness of the plan. Defining drought triggers can be difficult. Trigger levels change over time, that is, an appropriate trigger level for a particular system may change dramatically if that system has an increase in available infrastructure or if water demands change dramatically. Urban water triggers are often quite different from agriculture drought triggers, as the urban infrastructure can often mitigate the impacts of short-term droughts.

Who monitors drought conditions?

The Water Availability Task Force  (WATF) monitors drought conditions at a statewide level. Local water providers also monitor drought conditions by using data provided by various agencies and also by monitoring conditions within their own watersheds.

The WATF meets once a month throughout the water year (October 1 - September 30) except in October & December. During the month of March, the WATF meets jointly with the Flood Task Force.

All meetings are open to the public and the public is encouraged to attend. To be email notified of upcoming meetings, please visit the DNR Portal to add your name to our email distribution list.

What factors and indices are monitored for possible drought conditions?

Drought indicators are any single observation or combinations of observations that contribute to identifying the onset and/or continuation of a drought. Drought indicators can include measures of streamflow, precipitation, reservoir storage, the Palmer Modified Drought Severity Index, which is a function of precipitation, temperature, and the available water content of the soil, and other similar measures. The effectiveness of drought indicators depends on the region and the resources. Often, the degree of infrastructure development in a region may define the most appropriate indicators.

 

Explore Colorado's Drought Vulnerability Visualization Tool to see how your community economies may be impacted.

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Point of Contact

Megan Holcomb