May 17 2021Share

How Drought and Shortage Differ

By AMWUA Staff

The terms drought and shortage are routinely used together when talking about Arizona's hot and arid climate. While both drought and shortage involve a lack of water, their circumstances, impacts, and the challenges they bring differ.

DROUGHT is a prolonged period of less than average precipitation - meaning we are accumulating less moisture. It's weather-related and can occur in virtually all climates but happens more frequently in arid places like Arizona. Drought can have a far-reaching impact on our State's forests, agriculture, environmental quality, wildlife, as well as surface water and groundwater.

Arizona has been in a state of drought for over 20 years, surpassing the worst drought in more than 110 years of record keeping. Unfortunately, there is no single action we can take to end a drought. And even if we get some much-needed precipitation this monsoon season and next winter, it would still require multiple years of greater-than-average snow and rain to begin to heal the wounds left by the current drought.

To determine our drought status in Arizona, the Governor's Drought Interagency Coordinating Group, which includes experts on water, weather, climate, forests, and wildlife, collectively offer insight into recent weather events and analysis of what the near-term weather future may hold. The group meets twice a year to analyze Arizona's climate conditions and decide whether to recommend to the Governor that the ongoing drought declaration be continued or not. After meeting last week and considering all factors, the group will recommend to the Governor that the drought declaration in Arizona remains in place – a finding that was expected.

Before we explain shortage, it's important to note that drought does not necessarily result in a water shortage. Yet, a shortage can result from drought conditions, such as when precipitation levels are low, and those drought conditions directly impact a specific water source.

SHORTAGE occurs when there is an inadequate amount of water or a cut in water availability. A shortage may impact one water source while others are not affected. Additionally, shortage does not mean the collective supply from all water sources is insufficient to meet the overall water demands of customers.

A water shortage is not necessarily tied to the weather, but often it is. A pending shortage on the Colorado River system is the most relevant example. Suffering the consequences of a historic drought combined with over-allocation, water levels at Lake Mead have dropped to a historic low, which will trigger a shortage in the operation of the Colorado River. This shows how unfavorable conditions can impact the availability of water, thus creating a shortage and bringing a cut in water.

A shortage can also have different levels or tiers. Under the Drought Contingency Plan (DCP), Lake Mead's elevations determine the level of shortage and cuts in Colorado River operations. It is anticipated that in 2022, the River will be in a Tier 1 shortage, meaning Arizona will receive less of its Colorado River water that the Central Arizona Project (CAP) delivers, which will negatively impact agricultural users in Central Arizona. However, Colorado River water will still be available to municipalities. In the following years, we could enter different tiers of shortage and see more significant supply cuts.

The AMWUA cities are prepared for this situation and continue to prepare for further cuts to Colorado River water if deeper shortages occur. This is demonstrated by each AMWUA city having a 100-year designation of Assured Water Supply, which is possible because of their investing in different water supplies, infrastructure, and underground storage to ensure long-term sustainability. Additionally, the cities have created a variety of conservation programs that exceed the State's conservation requirements. This forward-thinking mindset allows our municipalities to weather decade-long droughts and minimize the impact of a shortage. Our communities have been developed with a keen awareness of the need to plan for extended periods of drought, capture and store all the water we can, and manage it as efficiently as possible to stretch those supplies. These extensive efforts help ensure we are ready regardless of whether a shortage is declared or not.

To learn more about our current drought status, visit ADWR's Interactive Drought Dashboard, which shows drought conditions in Arizona from 2000 to the present.

To learn more about the pending Colorado River Shortage, visit CAP's Know Your Water News.

For over 50 years, Arizona Municipal Water Users Association has worked to protect our member cities' ability to provide assured, safe, and sustainable water supplies to their communities. For more water information, visit

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