Understanding the difference between a drought and a water shortage

The terms drought and shortage are often used interchangeably when discussing water in the West. While both drought and shortage involve a lack of water, their circumstances, impacts, and challenges differ. Understanding the distinction between a drought and a water shortage is helpful for understanding the complexities of our water resources here in Arizona.

DROUGHT is a prolonged period of significantly reduced rainfall, leading to a lack of moisture in the environment. It is linked to weather patterns and can occur in various climates, but it is more common in dry regions like Arizona, where high temperatures exacerbate the situation. Drought affects more than just the water supply; it can damage state forests, diminish agricultural productivity, and negatively impact environmental health and wildlife habitats. It can also strain surface water and groundwater, resulting in long-lasting ecological issues. There is no simple solution for drought. Even if it rains heavily during one monsoon season or the following winter, it typically requires several years of above-average rainfall to restore the ecological balance disrupted by an exceptionally lengthy drought.

Arizona has a long-standing history of drought, presenting a persistent challenge for the state. Since June 1999, Arizona has been under a Drought Emergency Declaration, with a formal Drought Declaration in effect since May 2007. To assess the state's drought status, the Governor’s Drought Interagency Coordinating Group , composed of experts in water management, weather, climate, forests, and wildlife, reviews recent weather events and forecasts to evaluate near-term weather patterns. This group meets twice a year, in spring and fall, to analyze Arizona's climate conditions and determine whether to recommend the continuation of the ongoing drought declaration to the governor. They are scheduled to meet later in May. Based on current conditions, the group is expected to recommend that the drought declaration in Arizona remain in effect, a conclusion that would not be surprising given the circumstances.

A WATER SHORTAGE occurs when the water demand exceeds the available supply, regardless of weather conditions. While droughts can exacerbate water shortages, they are not the sole cause. Shortages may also arise from temporary issues like broken infrastructure or operational problems. These situations often necessitate water restrictions until the issue is resolved. Water shortages can have a localized impact, affecting specific sources such as rivers, reservoirs, wells, or aquifers, while leaving other sources unaffected. This distinction is important, especially in regions like Arizona, where diverse water supplies  are crucial for ensuring reliable water services.

Though a water shortage is not necessarily linked to weather, it can be influenced by it. The current Colorado River shortage  is the most relevant example. Experiencing the effects of a historic drought coupled with over-allocation, water levels at Lake Mead plummeted to a historic low, triggering the first Tier 1 Shortage in the operation of the Colorado River in 2021, which has continued into this year. This illustrates how unfavorable conditions can affect water availability, leading to a shortage and subsequent reductions in supply. A shortage can also have different levels or tiers, as demonstrated by the Colorado River shortage. We are anticipating that shortages will continue  on the Colorado River due to the overall hydrologic conditions affecting the river. 

While there is a difference between drought and a water 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 low precipitation levels, and those drought conditions directly impact a specific water source. 

The AMWUA cities recognize the ongoing cycle of drought and the challenges of living in an arid climate, which can affect their water sources in various ways. They continue to plan and invest in their water systems to withstand drought and to proactively prepare for potential shortages.   The cities are consistently working to ensure a reliable water supply , which is essential for our desert communities and our state's overall economy.

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.

For 56 years, the 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 www.amwua.org .