Wildfires can impact our water

Published Jul 08, 2024

Higher temperatures in our dry climate naturally increase the chances of wildfires in our state, which is currently evident as a number of fires burn around our state. That is why this time of year, it is important to remember that we need to use extreme caution because we all play a part in preventing wildfires and limiting the damage protects the diverse landscape across our state and the watersheds that provide water to the Valley.

We know that wildfires devastate forest vegetation. They leave behind large amounts of ash, heavy metals, organic materials, and sediments that flow into the rivers and accumulate in reservoirs. That impacts the watersheds significantly and affects the quality and sustainability of the water.

Outside the Valley is the 8.3 million-acre watershed that channels the snowmelt and rainfall into streams, creeks, and the Salt and Verde Rivers that then flow into Lake Roosevelt and other Salt River Project (SRP)  reservoirs, which is one of the AMWUA cities’ sources of water .

The health of these watersheds is critical to life in the desert. Not only do we face challenges due to our long-standing drought, but forest fires also impact the quality and sustainability of our water supply. And Arizona’s forests are no stranger to fire. 

Since 2000, 1.8 million acres have burned on the Salt and Verde watersheds  in seven mega-fires. The 2015 Sunflower fire in the Verde River watershed, which took place during the monsoon season, lasted for 16 days, resulting in highly turbid water coming down the River and entering water treatment plants here in the Valley. As a result, those treatment plants had to increase chemical use to clean the water by more than 50 percent for over two months. SRP had to divert ash- and debris-laden water into the rivers as it was untreatable by the water treatment plants at the time.

A healthy forest acts as a storage and filtration system. In the winter, the canopy prevents the snowpack from melting too fast. Slowing the rate at which the snow melts provides the Valley with a steady water supply- in spring and summer when we need it the most. Scorched forests expose snow to excessive sunlight, causing it to melt more quickly and increasing the likelihood of floods. Waste from runoff settles at the base of the dams, reducing reservoir capacity and affecting water quality.

With good levels of precipitation and snowpack from this past winter, you would think it would greatly help our forests and minimize the danger of fires as the temperatures rise. In some ways, that is true, as wet winters can hold off the immediate impact of escalating desert temperatures. Still, a wet winter also brings increased vegetation, such as grass and wildflowers, which turns into fuel once dried by our scorching sun. So, although the forests may look good after a wet winter, hot temperatures increase the danger of wildfires, and we are already seeing examples across our state as over a dozen fires have already occurred this season.

The AMWUA cities have long recognized the critical connection between the watersheds and the Valley’s water supply. They have contributed funding for continuing efforts by SRP, the Nature Conservancy, and others to protect the watersheds and reduce the risk of catastrophic fires.

While those efforts are essential to keeping our forests healthy, we all must do our part  to protect our diverse topography by practicing care in our State Parks , during outdoor recreation, and even at home in our own backyards. Please enjoy Arizona’s great outdoors, but use extreme caution with fire, and be aware that equipment and all-terrain vehicles can create sparks that are very dangerous in our arid landscape. Our diligence will protect our valuable forest areas and will ensure the sustainability of our quality water supplies.

Currently, SRP is partnering with several entities to look for additional ways to prevent fires and further protect the watershed. Recently, it was announced that SRP is collaborating with ASU  to determine the water benefits of forest thinning projects.

For 55 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 .