Drought 101

Editorial authored by Charlie Ester III, Director of Water Supply at SRP 

I will never forget the moment I stepped off a helicopter and onto the dry lakebed of Roosevelt Lake, less than one decade into our current drought. Unbelievably, a few years before that, and in “wet” years to come, the lake’s water level would be 50 feet above my head. 

That dry lakebed moment was in 2002. Since then, wet winters have abundantly refilled the largest lake in the SRP system, but drought continues to prevail in Arizona.  

Because more than 3 million residents depend on our water supply to live, work and play in the Valley, many have questions about the lack of rainfall and how it affects our lives.   

What is drought? How does it happen? 

Deserts are landscapes of sparse vegetation, extreme heat and low rainfall. Drought occurs when the small amount of expected rainfall is dramatically reduced. 

You may wonder how it’s possible to have periods of wet weather and flood-causing storms but still be in drought. It all comes down to two things: climate and definition.  

Drought is defined as a period of time with reduced precipitation. It can cause serious problems. Droughts do not have a defined start date. In fact, many believe our current drought began in the mid-1990s.   

Meteorologists determine drought based on things such as:

• Rainfall
• Soil conditions
• Streamflow, or lack thereof

If I hadn’t told you the Valley was currently in an extreme drought, would you have guessed it? According to the Arizona Department of Water Resources, Arizona has experienced three severe droughts in the last 120 years — one in the early 1900s, one in the 1950s and the current 24-year drought. 

Impacts of drought 

The impacts of drought can be immediate. Thankfully, our water storage system, dams and robust water management plans lessen the impact on residents. We make the most out of our “wet” years by storing water for the dry years.  

A century ago, the Phoenix area was mostly farmland. When a drought occurred, crops withered and died. Often, farmers lost everything but could regrow crops and make profits with the next season.  

A drought today has far more lasting impacts than ever before. It requires more significant planning to supply water for residents year after year.   

Arizona’s unique climate: Should we expect drought? 

Drought cycles spanning a few decades are normal for our arid region. We know this because we have access to tree ring study data dating back 1,000 years. This study clearly defines periods of drought and plentiful rainfall. 

For our region, extended drought periods also include “spike years.” For instance, in 2017, rainfall increased so much that SRP’s reservoir capacity climbed from 44% full to 76% full in one winter. That spike year was followed by 2018, the driest winter in SRP’s history with records dating back to 1898. 

Wet, dry, dry and wet again — history repeats itself. We never know when Arizona may enter the next wet or dry cycle, so we need to stay on our toes to meet the Valley’s water needs. 

Our watershed: How SRP plans for drought in the desert 

The Phoenix metropolitan area is well-positioned to survive extended droughts. This is due to the water supply from SRP, proactive planning and the Central Arizona Project (CAP). We assume every year is the beginning of the next drought period.  

In fact, SRP manages surface water and groundwater to last through 11 continuous dry years! Combine that planning and commitment to water conservation from SRP, its customers and our water partners across the state and supplies can stretch even further.  

SRP manages surface water and groundwater so the Valley will have supplies to last through 11 continuously dry years. Read about how we make the most out of every drop. 

SRP’s robust water system does not rely on just our seven reservoirs. It includes the flexibility to pull from an extensive network of groundwater wells. When necessary, SRP can supplement our surface water from the Salt and Verde reservoirs with groundwater pumped from our 270 wells in the Valley. 

This can supply about 50% of the water SRP delivers during a drought year.  We also work with many partners to restore groundwater levels so that when needed, the resource is available.  

How SRP reduces drought risks 

Because of the severely dry conditions, SRP increased pumping from 150,000 acre-feet to 200,000 acre-feet in 2018. In case the winter of 2018–19 remained in severe drought, we did that as insurance (so to speak). Fortunately, we had a “wet” winter last year and reduced pumping again. 

SRP’s water supplies are just one part of the region’s water mix. To plan for the region’s future water needs, we work closely with: 

• Valley municipalities
• The Central Arizona Project (CAP)
• Tribal nations
• The Arizona Department of Water Resources

Constant planning for drought 

As a water provider for more than a century, SRP has a great deal of historical knowledge that we use to our advantage. By planning as if every year is the start of the next 11-year drought, our hydrologists will never be surprised by a dry winter (A hydrologist is someone who studies water – a very important role at SRP! ).

For instance, think back to the much-advertised “Godzilla El Niño” drought-ending winter event four years ago. We planned for much lower-than-normal runoff and were proven correct.   

Thanks to our calculated modeling, SRP reservoirs remained in good shape at the end of the poor 2016 El Niño runoff season. They are still two-thirds fuller today compared to every year since 1950. We believe it is much wiser to constantly plan for drought than to be surprised by a dry winter.  

Research informs our future 

Climate change in Arizona doesn’t necessarily mean more drought. Twenty-four years into the current drought cycle, we are about due for an end to this extreme drought in Arizona. 

What comes next though may surprise you. For Arizona, climate change will mean even more dramatic highs and lows from year to year. 

At SRP, our meteorologists and hydrologists are conducting research with scientists from Arizona universities. This helps us to understand what climate models built across the world predict for our unique climate in Arizona.  

Climate models are important because they predict what changes may affect Arizona over the next 50 or more years. Among the models, the main theme is that we will be getting warmer. 

When it comes to precipitation and the future, Arizona will likely see repeated droughts and wet spells. That sounds a lot like our past. SRP is prepared to supply the necessary water resources for our vibrant area. 

Planning for the future 

Learn more about how SRP is conserving water.