A healthy watershed in the Spring Mountains is important, but wildfires can cause long-term damage that creates devastating flooding conditions for the residents of Las Vegas
On July 1st, 2013 the Carpenter 1 Fire erupted and over weeks burned 27,881 acres of the Spring Mountains National Recreation Area, otherwise known as Mount Charleston. The Carpenter 1 Fire engulfed the majority of the Harris Springs Canyon Watershed and the resulting damage changed how the water flowed downhill. The Harris Springs Canyon Watershed sits above Las Vegas. The steep hillsides of the canyon funnel flowing water downhill into the Kyle Canyon Detention Basin, and then downward to the northern end of Las Vegas and into the Las Vegas Valley Watershed. Before the fire, plants, roots, and soil held in rainwater, and slowed rainfall flows downhill. The water slowly filtered downhill through washes, eventually seeping into the ground as part of the natural water cycle. The fire changed this process. After the fire, burned plants and soil were unable to slow the flow of water on the hillsides. Plants and leaves were burned away and high flows of water cleared the washes. Rain flowed down the steep slopes, building in great amounts and force, and down through the canyon and to the Las Vegas valley below.
The fire changed how water flowed through the canyon. The fire burned not only plant material like trees, bushes, flowers, and grass, but also burned the soil itself. Some burned soil becomes water-repellent, referred to as hydrophobic, making the ground unable to soak up rainfall. Areas where leaves, twigs, and dirt could hold back normal water flow were washed away. After the fire, rainfall flowed over the soil and down the steep hillsides rapidly, collecting into large amounts of water with a lot of speed. This massive force of water took soil, trees, and debris with it as it flowed downhill towards Las Vegas.
After the Carpenter 1 Fire, rain drops in the Harris Springs Canyon Watershed created damaging floods down in the Las Vegas Valley. As rain fell in 2013 and 2014, any measurable rainfall swiftly washed soil and the burned trees and debris downhill to the Kyle Canyon Detention Basin, and often overflowed into the northwest portion of the Las Vegas valley. Rainfall also washed some of the fire retardant, dropped by firefighting planes and helicopters into the canyon during the fire, and mixed into the mud filled debris flowing into town creating a bubbled mess of mud, fire retardant, water, and burned material. Significant rainfall in the Spring Mountains would typically eventually flow downhill through the valley's system of natural and manmade washes to reach Lake Mead and the Colorado River. However, the mud and debris filled water clogged sewer drains and narrow flow points, causing roads to turn into rivers and caused massive problems on roads and highways (LINK to Las Vegas Sun article with a gallery of flood images in Las Vegas).
The heavy rainfall on the recently-burned hillsides washed away valuable soil and native seeds that would have grown into new plant life and habitat for animals, altering the canyon’s ability to recover on its own. The Forest Service BAER Team assessed the damages in summer of 2013, making recommendations and plans for any restoration work that was necessary. One significant addition to the area during the recovery process was the installation of rain gauges. These gauges alert local authorities if enough rain has fallen in Harris Springs Canyon to potentially create a flooding event that could cause problems for residents below. Valley residents have seen the billboards warning people to stay out of a flood and stay alive, with slogans like "Turn around, don't drown", because these floods can carry away and submerge humans, cars, and the roads themselves. Restoring the Harris Springs Canyon Watershed helps alleviate these sorts of post-fire massive debris-filled flooding events, and help keep nearby communities safe.
Healthy watersheds provide many natural benefits to both the immediate area and nearby cities. Homes and businesses are in the area where flood damage occurred, roads and highways were destroyed, and people evacuated. Since 2013, even more homes and businesses have been built closer to the Spring Mountains. A healthy watershed means safe habitat for animals that live in the area, like the threatened desert tortoise, as well as the large population of Las Vegas valley residents below the watershed. A well-functioning watershed in the Harris Springs area lowers the chance of a dangerous debris-filled flood for Kyle Canyon and Las Vegas residents below. A watershed can naturally filter out pollutants and recharge groundwater, reducing water waste by keeping the water in the natural water cycle, some of it eventually available for people to use in their homes. A healthy watershed will reduce the occurance of mud-filled floods that can devastate homes and businesses, helping the Las Vegas economy. And if the watershed is healthy enough, it can be open for recreation like hiking, biking, and off-roading, providing the much needed outdoor experience.