One of the benefits of living in Steamboat Springs is its clean mountain air. But it hasn't always been this clean.
Fifteen years ago, Steamboat had its own brown cloud, and the city was named one of the seven worst air-quality cities in Colorado. The federal government told Steamboat it had to clean up its act. And the city responded.
The small municipal street sweepers that prowl Steam-boat's streets this time of year are on pollution patrol. They sweep up the dust left when cars and trucks pulverize the crushed rock that provides traction on snow-covered roads. Street sanding was a big contributor to Steamboat's air pollution problems in the late 1980s and early 1990s.
"The city of Steamboat is doing a fantastic job," said Mike Zopf, director of the Routt County Environmental Health Department. "They went beyond what they were required to do."
Zopf and his staff check the city's four air pollution-monitoring devices every day and file reports with the Colorado Department of Health.
"The last time there was a violation was in 1996," Zopf said Wednesday. "Back in 1990, we had a few bad episodes."
Zopf was referring to the period between 1989 and 1990, when Steamboat violated federal air quality standards on three occasions.
Steamboat Public Works Director Jim Weber said the city cannot afford to be complacent when it comes to air pollution.
"We have reached attainment status as far as the state is concerned," Weber said. "We do still need to monitor air quality, because a failure of a particulate level would create the city falling back into a non-attainment category. So, we still have to be very cognizant of that. The state is still keeping an eye on this area."
The PM-10 problem
The air pollution that once plagued Steamboat and other mountain towns such as Aspen, Crested Butte and Telluride is referred to by environmental scientists as "PM-10." The acronym refers to particles of 10 microns or less that are suspended in the air. Ten microns is about the width of a human hair.
Steamboat uses crushed volcanic rock to "sand" its streets. The small rocks have sharp edges -- good for making streets safer. However, the rock also breaks down quickly under truck and car tires. Vehicles kick the dust into the air, where it is suspended.
The city's Public Works Dep-artment has two street sweepers that remove the volcanic dust from roads.
But street sanding wasn't the only source of Steamboat's PM-10 pollution. Residents also depended heavily on wood-burning stoves and fireplaces for domestic heating. Many of the city's resort condominium projects were built to include fireplaces and wood-burning stoves.
Gazing down Lincoln Avenue from the ski slopes on a late-March afternoon in 1990, it was possible to see a brown haze over Old Town Steamboat.
In Colorado's mountain valleys, cold winter nights often cause a phenomenon known as a temperature inversion -- a layer of warm air traps cold air near the ground. During the 1980s in places such as Steamboat, smoke from burning wood was trapped at ground level with the cold air. A motorist driving on Walton Creek Road could see the smoke layer hovering above the street.
In 1987, the city began addressing the problem. Some of those steps were taken before Steamboat was found in violation of federal clean air standards. City officials passed an ordinance requiring multi-family residential projects to convert wood burners, including fireplaces, to cleaner natural gas. Open-hearth fireplaces in single-family homes and duplexes were exempt. However, owners of wood-burning stoves were required to retrofit their appliances with catalytic converters.
Zopf said the air quality in the upper Yampa Vall-ey also has benefited from the retrofit of the coal-burning Hayden Station power plant with pollution control equipment. When combined with the city's efforts, the results are notable, Zopf said.
A year's worth of readings from pollution-monitoring dev-ices on the roof of the Routt County Courthouse Annex show particulate levels are about half of what is allowable under federal standards, Zopf said.
"I think some people probably take it for granted, but people who were here back then know the difference," Zopf said. "It's a great success story."