Five Things You Need To Know Right Now About Drought

By Warren Tenney

Ongoing headlines about drought in the southwest are confusing and often seem contradictory. Two weeks ago, a panel of experts advised the Governor’s Office that Arizona’s drought is not over and will last, at least, another year. After a rainy winter, that’s a surprise for many people who follow the state’s drought status maps. These monthly drought maps show no portion of Arizona remaining in “extreme” or “severe” drought. Then there is the conundrum created by the decline of Lake Mead, the Colorado River reservoir critical to Arizona’s water supplies. This winter’s heavy snow in the Rocky Mountains of Colorado and Wyoming means Lake Mead will receive enough water to avoid a shortage declaration. Yet, the Lake’s levels remain a source of great concern among water professionals. Oh, and why has California, but not Arizona, declared its drought over?

Here are five questions and the answers you need to know about drought to help you cut through the confusion.

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Here is where to follow Arizona’s monthly drought conditions: http://www.azwater.gov/AzDWR/StatewidePlanning/Drought/DroughtStatus2.htm

1. What is drought?

A drought is not a moment in time. Drought is a cycle. Research shows that drought cycles and wet cycles in Arizona run 20 to 30 years. That’s why you hear water experts say: One rainy winter doesn’t end a drought. One rainy winter can temporarily ease “drought conditions” in some areas of the state. The current drought cycle began around 1996. If rainfall and snowfall continue to be above average over the next several years then Arizona’s climate experts would be more likely to call this drought finished. These same experts say there is a 50 percent chance of that happening. The wild card is climate change.

2. Why is Lake Mead still at worrisome low levels?

Lake Mead is a reservoir that contains Colorado River water behind Hoover Dam. The legal allotments of Lake Mead water given to states and communities outstrip the average amount of Colorado River water entering the Lake. Even without a drought, normal withdrawals of water from Lake Mead would cause it to fall an average of 12 feet every year.  The drought on the Colorado River Basin has exacerbated the situation.  Voluntary efforts by states that depend on Lake Mead have kept it from falling to a level where the federal government would declare a shortage. A shortage declaration would mean less Colorado River water would be delivered to Arizona. It would affect farmers first, but if Lake Mead levels fall farther, Colorado River water supplies to cities would eventually be cut.  So far, the Colorado River has been able to keep delivering, but living on the edge of shortage is unacceptable to water managers. The Arizona Department of Water Resources is working with the state’s cities, Native American communities, farmers and industries to voluntarily cut back on water taken from Mead. Once Arizona reaches an internal agreement it can finish negotiations with California, Nevada and Mexico to voluntarily reduce legal allotments of Colorado River water to match the reality of what the river can supply. Right now, Lake Mead is only 10 feet higher than it was this time last year.

Lake Mead NO CREDIT required

Lake Mead

3. After 20 years of drought, why are Arizona’s water supplies not critically low?

Drought is a normal occurrence in our arid environment. Central Arizona has built, planned, and managed water supplies to ensure reliability during drought cycles.  Massive reservoirs capture water during wet periods for times when precipitation is scarce. The Arizona Groundwater Act of 1980 requires cities and farmers in the most populated areas of the state to implement conservation programs, protect the groundwater from over pumping and rely on renewable surface (river) water instead. The majority of the state’s water supply comes from the Colorado River via the Central Arizona Project (CAP) and the Salt River via Salt River Project (SRP).  Virtually all wastewater is recycled and put to use, and water is stored underground for use in shortage.  A limited amount of groundwater is pumped from the aquifers for use, as well. Multiple sources of water allow cities to offset reductions in one or more supplies. For example, Arizona’s drought has reduced the amount of water in SRP reservoirs in the mountains east of Phoenix, but SRP has been able to offset possible shortages by pumping from its numerous wells. Arizona law requires Valley cities to offset every acre-foot of groundwater SRP pumps by recharging (or returning water to) the aquifers from their renewable water supplies, such as extra Colorado River water (ordered but not immediately needed) or recycled wastewater. This keeps the Valley’s aquifers in good condition and hedges against shortages.

Aerial shots of GRUSP

Granite Reef Underground Storage Project   Photo: Mark Durben

4. So, if we’re in good shape, do we still need to conserve water?

We live in a desert. Long-term, ongoing conservation efforts are something AMWUA member cities promote tirelessly, and for good reason. Drought is an uncontrollable weather phenomenon and the impact of climate change is unknown. Our groundwater supplies are finite. Once used, aquifers replenish over decades, not years, and usually not to previous capacity. Using less water on a daily basis means leaving more water in the ground and storing more water for a time when river water supplies are short. If shortages were to prevent cities from meeting normal, everyday demands for water, all AMWUA cities, by law, have shortage-preparedness plans ready to go. These plans are designed to incrementally reduce water use to bring demand in line with available supplies while protecting our quality of life and the economy. Despite that, no city wants to declare a water shortage. So for now, keep taking those short showers, keep watering those shade trees efficiently, and keep using water wisely. Your city will let you know when it needs more help.

5. Why is Arizona’s drought continuing while California has declared that its drought is over?

California has declared an end to the drought’s State of Emergency, but that doesn’t mean it is entirely out of the drought that has gripped the state since 2012. Due to the economic impacts of ongoing drought, record low reservoir levels, and snowpack at 20 percent of normal levels, California’s governor declared in January 2014 a State of Emergency. In January 2015, with no end to drought in site, cities and towns across the state were required to reduce water use by 25 percent. Recent record-breaking precipitation freed the northern part of the state from drought and refilled the majority of reservoirs, allowing the state to rescind the mandatory water use reductions and lift the emergency declaration for all but four counties. However, almost half the state remains in severe drought.

Arizona’s current drought began around 1996.  Arizona’s Drought Emergency Declaration has been in effect since June 1999 and still remains in effect. We haven’t yet seen enough wet weather across the state to lift either the drought or the declaration. 

For 48 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 www.amwua.org.

Drought: Five Things You Need To Know About This Rainy Winter

By Warren Tenney

Many people are wondering what this rainy, snowy winter means for Arizona after more than two decades of drought. Here are five things we know right now.

1. It’s raining and snowing in the right places. So far, it has been raining and snowing in locations that have the potential to increase water in two major reservoirs, Roosevelt Lake and Lake Mead. These reservoirs are key to drinking water supplies for the majority of Arizona’s population.

  • Lake Mead relies on runoff from snow pack in the Upper Colorado River Basin, primarily from two main tributaries: the Green River in southwestern Wyoming and the Upper Colorado River in western Colorado. December snowpack in the Colorado River Basin has ranged from 50 percent to three times above normal.  The result of this above normal precipitation will likely boost the reservoir levels of Lake Mead.
  • Roosevelt Lake relies on rain and snow in the watershed that feeds the Salt River. This watershed reaches into the high country northeast of Phoenix. So far, the watershed has received about 45 percent more precipitation than normal. As of January 25th, 211,000 acre-feet of water had flowed into Roosevelt Lake. (One acre-foot of water is enough to serve three average Arizona households for a year.)

2. This is a good start. Weather in February and March must remain cold and wet to hold and increase the gains and potential gains in both reservoirs. Water resource managers are pleased with rain but prefer snow accompanied by extended weeks of cold temperatures. Low temperatures keep the snow on the ground longer, which stops the water in the ground from evaporating and helps to reduce the threat of summer wildfires. The slow flow from melting snow also delivers cleaner water and is easier to manage in a water delivery system. So while it has already been a good winter, we will have to wait until April to know if it has been a great season.

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This is a map of the  watershed where the springs, creeks and rivers originate that feed into Roosevelt Lake, a key drinking water reservoir for the Phoenix Metro area.

3. The drought is not over. Research shows that drought cycles and wet cycles in Arizona run 20 to 30 years. A drought cycle has fewer wet years than dry and a wet cycle has a greater number of above average rainy years. The current record-breaking drought cycle began around 1996. The last six years have been the driest on record in the Salt and Verde rivers’ watersheds. If the weather follows historical trends, the current drought could be coming to a close within the next several years, but there’s no certainty and it does not factor in climate change. It would take a few years of greater than average snow and rain to begin to heal the wounds left by the current drought. This includes helping to replenish local aquifers used to back up water available in dams and reservoirs. Plus, two or three years of well above-average precipitation on the watersheds that feed the Salt and Verde rivers would help to re-establish depleted wildlife, such as quail and deer. That much precipitation would help to restore overgrazed grasslands and begin to create a healthier forest, with trees not as susceptible to diseases and bark beetle infestation.

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4. AMWUA cities are built for drought. Sunshine is the norm in Central Arizona and rain is an event. We have never denied that we live in an arid part of the country and we plan for drought cycles. AMWUA cities save water underground for future use, keep leaks within their water distribution systems to some of the lowest rates in the country, and re-use 99 percent of their wastewater. Salt River Project (SRP) operates the system of reservoirs and canals that store water from the Salt and Verde rivers. After a rare rainy year in 2010, SRP has faced six dry years on the rivers’ watersheds. Despite record low precipitation, Roosevelt Lake has remained half full and SRP has been able to fill water orders for farmers, industries and cities. SRP was forced to limit water orders by 33 percent in 2002, the driest year in the Southwest in 1,200 years. That year, the SRP system was only 25 percent full and Roosevelt Lake alone was down to 10 percent full. It was the first reduction since the 1950s.

Central Arizona Project (CAP) operates the canal that brings Colorado River water released from Lake Mead to Arizona. CAP has not yet had to reduce water supplies due to a Colorado River shortage. The state’s cities, farmers and industries currently are working together to maintain and increase the level of water stored in Lake Mead and prevent a water shortage declaration next year. The recent increase in winter precipitation and snowpack in the Colorado River Basin decreases the chances that a shortage would be declared in 2018. So, while we regularly face metrological droughts, our water supply droughts are rare.

5. You can make the rain count. Homeowners, apartment managers and businesses make a contribution to our reservoirs when they turn off their irrigation systems and auto-fills on their pools each time it rains. More homeowners and communities also are harvesting the rain by contouring their landscapes to hold storm runoff. Swales built around trees and plants help rainwater stay in place longer so the water soaks deep into the landscape and stays available to plants and trees longer. All of this reduces the need to irrigate and the demand on city water supplies, which in turn saves more drinking water for drinking.

For 48 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 http://www.amwua.org.