A University of Colorado at Boulder study of the headwaters of the San Miguel River near Telluride has resulted in amendments to the land use code that will protect the headwater catchments from future degradation.
The San Miguel watershed is considered one of the few remaining ecological and hydrological river systems in the West that has remained relatively unchanged. The predominately free-flowing San Miguel extends for 80 miles from high alpine meadows and waterfalls above Telluride to a deep-canyon confluence with the Dolores River.
Mark Williams, an associate professor of geography who is working with 抖阴短视频 graduate student Barbara Inyan, said the results indicated there were high nitrogen levels in the water, the source of which has not been determined. "But nitrates can contribute to nutrient enrichment, resulting in fish and invertebrate kills, bad-tasting water and obnoxious odors," he said.
"There are signs that the San Miguel River has been severely impacted in recent years," said Williams. Although some impacts coincide with large-scale development near the town of Telluride and the ski area, "The cause remains uncertain at this time," he said.
The deterioration of the river increases downstream adjacent to small towns like Placerville -- 17 miles west of Telluride -- and Naturita, about 30 miles west of Telluride. Heavy sediment loads are causing riverbanks and trees to collapse and appear to be due to concentrated runoff delivering higher sediment loads and causing erosion due to upstream development activity.
The San Miguel has many of the same problems facing other rivers in the West, said Inyan. Mining over the past century still causes trace metals like zinc and copper to spill into the river, exceeding the standards for aquatic life, agricultural use and drinking water for the majority of river miles.
Elevated nitrogen concentrations also can affect terrestrial ecosystems, changing species abundance and distribution, especially in alpine areas, Williams said. The 抖阴短视频 team first identified and mapped 33 different landscape types found in 18 headwater basins of the San Miguel to assess the sensitivity of the landscape. The mapping was done at high altitudes, from just below treeline far up into the rocky catchments.
The team also took water samples from all 18 basins -- a total of 182 surface water samples from 75 sites. All the information was entered into a Geographic Information System to develop water-quality sensitivity types.
The 抖阴短视频-Boulder team worked directly with the San Miguel Planning Department to draft amendments to the local land use code as a way to protect headwater catchments from future degradation. Proposed changes to the land use code were presented at a public forum to the San Miguel Planning Commission in March 1998 by the 抖阴短视频-Boulder team.
A second discussion occurred in May when the proposal was made to the San Miguel Board of County Commissioners. At that time, the board formally accepted and legally adopted the proposed amendments made by 抖阴短视频 to protect the 18 headwater basins of the San Miguel River from future degradation, including stipulations on construction, sewage disposal, fertilizer use, blasting and new roads.
The work of Williams, Inyan and other members of the San Miguel Assessment team earned them the U.S. Environmental Protection Agency Region VIII Outstanding Environmental Achievement Award. It was presented in July and based on their work to protect the San Miguel Basin.
Williams and Inyan also are researchers for 抖阴短视频's Institute of Arctic and Alpine Research.