Forest fire, water quality and the incident at Buffalo Creek

Forest fire, water quality and the incident at Buffalo Creek

Gordon Illg

When the rains began to fall, few realized what would result from a problem that started with wildfire strategies and ended with. Denver’s water supply. “Wait until you see the devastation,” Lt. Fritz Day of the Jefferson County, Colorado, sheriff’s department warned. “It’s one click short of nuclear.”The road in front of us was strewn with overturned cars and trucks, uprooted old trees, and giant sections of asphalt. Visitors and residents alike say they find it hard to believe tiny Buffalo Creek could devastate an entire valley.

As a matter of fact, had heavy rains been the sole cause of the July 12, 1996, flash flood, Buffalo Creek’s floodplain probably would have suffered little damage. But the disaster began almost two months before the first fateful raindrop fell, when an unattended campfire in nearby Pike National Forest ignited the surrounding woodlands. Spurred on by hot, windy weather and a drier-than-normal spring, the fire blackened 11,900 acres before it was brought under control.

Forest fires coat surrounding soil with an organic patina that makes it almost waterproof, studies show. So when the torrential July rainstorm drenched the charred slopes, “it was just like dumping water over concrete,” said volunteer fireman Scott Melvin. In 45 minutes, more than 2.5 inches of rain fell on an area that gets only 13 inches a year. The town was demolished.

“We were still counting ourselves as pretty lucky for saving our home from the fire when the creek washed everything away,” one Buffalo Creek resident said.

Before the fire, that much rain would merely have made the creek a hazardous place. Afterward, not only did an increased amount of water flow into the creek, the burned slopes themselves literally poured down every drainage.

“I’ve been here every summer since 1921. I’ve seen this gully flooded many times, but this is the worst,” said Katherine Ramus, 86, owner/manager of Buffalo Ridge’s Blue Jay Inn. “I’ve seen floods bring down trees and beds, and one time a dead cow. But never anything like this.”

A mountain of sediment

Few residents of the watershed had seen anything like it before. Sediment piled up in the North Fork of the South Platte River, forming a natural sand dam that backed up more than eight feet of water. When it gave way, water and sediment it loosed swamped the primary source of Denver’s water, Strontia Springs Reservoir. It took a 12- member crew more than two months to clear the reservoir of logs, propane tanks, refrigerators, tires and other objects in the flood’s path.

The reservoir feeds water to the nearby Foothills Water Treatment Plant. Sediment deposits there nearly equaled the plant’s total after 13 years in operation. It shut down for several days. Buffalo Creek residents went without running water from several days to several weeks, depending on where they were located on the delivery system. Although there was nothing harmful in the water, hundreds complained about the appearance and taste, said Bob Weir, deputy director of operations and maintenance for Denver Water.

And the problem didn’t stop with the receding water: Mountains of sediment now line the creek, a problem water systems will contend with for years.

Coors Brewing Company trucked in bottled water daily, and retailer Eddie Bauer donated 5 percent of opening-day revenues from a new store to replant the burned area through AMERICAN FORESTS’ Global ReLeaf Forests program (see “The Story in the Stores,” page 30).

Lessons learned

The 11,900-acre fire that started the devastation was just a small symptom of a huge problem along Colorado’s Front Range. Buffalo Creek is part of an almost continuous 2,500-square mile swath of ponderosa pine forest that’s primed for catastrophic fires. And this disaster-in-the-making can be attributed primarily to the Smokey Bear mentality – that all fire be supressed, although the decrease in logging has also contributed.

Some Buffalo Creek residents feel the Forest Service could have done more to discourage fires before this incident, but a state forester argues that this landscape evolved because of fire. “Fires are going to occur here regardless of the rules and regulations,” said Ron Zeleny, of the Colorado State Forest Service. “In fact, discouraging fires is part of what created this problem in the first place.”

In pre-settlement times, fire would sweep through the forest every five to 15 years, keeping the forest open and the underbrush from becoming too dense, rejuvenating the soil with nutrients from the burned vegetation, and keeping the amount of “fuel” low, which meant fires rarely burned hot enough to harm mature trees. Then this area would have had 15-20 stems per acre; on May 17, 1996, there were 120-plus.

Preventative measures too late

For more than a decade, the Forest Service has realized that ponderosa pine forests require fire to stay healthy, and the first prescribed burns in the South Platte District were conducted in 1980. Ironically, preventive measures, including thinning trees and controlled burns, had been initiated in the Buffalo Creek area just shortly before the fire. The South Platte Ranger District is more restricted than most in its controlled burns. Because of the district’s proximity to Denver, and because fires detract considerably from air quality, they can only carry out controlled burns when Denver’s air quality is relatively good. This severely limits the times these burns can be conducted in this forest.

There are other problems, too. Zeleny said, “Part of the difficulty in keeping these forests thinned is the market for wood products is diminishing. The trees we want cut are the young, small-diameter trees. Ponderosa pine don’t make good Christmas trees, and the market for firewood has been heavily impacted by the mandate for cleaner air.”

If the preventive measures had been carried out before the fire erupted, undoubtedly the effect on the surrounding forest would’ve been considerably reduced. It’s impossible to know how that would have affected the flood, but one interesting aspect is now being studied.

Scientists are looking into the possibility that the amount of rain that fell that day actually may have increased because of the fire. In studying the effects of four major storms to hit the area last year, Bob Jarrett, a U.S. Geological Survey research hydrologist, found that each reached its greatest intensity over the burned region, then dissipated over unburned forest.

“It’s still too soon to say with any certainty whether burned areas trigger more precipitation from storms,” Jarrett said, “but it’s definitely worth studying because of the future potential for flooding in communities near forest fires.”

The area may have been doomed to flood regardless of the effect the fire had. The Buffalo Creek area is composed of Pike’s Peak granite, and this granitic soil is infertile, poorly structured, and erodes easily. “If you look at these slopes wrong, they start to erode,” lamented Gary Shaffer, a fire management officer with the South Platte Ranger District.

“It appears,” said Deborah Martin, a researcher with the U.S. Geological Survey team that analyzed the erosion and deposition from the flood, “that this area has flooded and suffered severe erosion after fires many times in the past. This kind of occurrence may be a normal reaction to fire in this watershed.”

Whether post-fire flooding is a normal occurrence here or not, a healthier, more open ponderosa pine forest would probably have endured the fire. And officials are taking a hard look at the fact that the cost of restoration after the fire just about matched the $3 million it took to fight the fire. Another potential expense: the water department still is considering a series of small dams to trap sediment that remains above Strontia Springs Reservoir and poses a problem for years to come.

Due to the aridity of this area and the quality of the soil, it will be at least a century before the new forest approaches the level of maturity of the one that was lost.

“We’re beginning to question traditional funding priorities,” Shaffer said. “Perhaps the millions of dollars (in cleanup costs) would’ve been better spent on preventive measures, such as thinning the forest and controlled burns, rather than applying Band-Aids to a black landscape.”

Cathy and Gordon Illg are freelance writers in Lakewood, Colorado.

COPYRIGHT 1997 American Forests

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