Introduction and History
The Valley Floor is a unique ecosystem in Southern Colorado. In spite of the impact of human activities, it has retained biological integrity. Its wetlands and riparian areas, in particular, provide important habitats and resources. These habitats are currently at risk from on-site and upstream activities and development.
The future of the Valley Floor and the future of the Telluride Region are intrinsically linked. In the interests of the best future for both, SEI and a group of Telluride citizens undertook a scientific evaluation of the San Miguel Headwaters and the Valley Floor. The approach was to move beyond polarized opinions and to provide scientific guidelines for sustainable land management.
Toward this end, SEI gathered and evaluated information to answer two central questions:
1. What is the biological value and health of the ecosystem?
2. What will it take to maintain and/or restore the natural habitat?
SEIís research into these questions included habitat, plant, and invertebrate surveys conducted in 2000-01 (these were conducted on the public but not the privately owned portion of the Valley Floor); review of existing scientific information; and analysis of new scientific data. SEI also studied proposed development plans and community land use reports to provide additional context for the study.
1. Biogeographically, the San Miguel mountains and river valley are unique. The region today is an island of biodiversity isolated by plains, mountains, and desert. It contains a mix of species that migrated across the Bering Sea from Siberia, the Himalayas, and elsewhere between glacial melts (1.6 through 6.8 million years ago).
2. The San Miguel River is one of the few remaining undammed rivers in Colorado, and its upper reaches are among the most pristine. [Willits, 2001] The meandering reaches of the Valley Floor contain its best fish habitat and supports cold water species such as trout.
3. Wetlands occupy most of the Valley Floor. Some of these wetlands are fens, an ancient and irreplaceable type of wetland that receives its water from groundwater and is usually dominated by sedges and grasses growing in peat. Fens take thousands of years to develop and are at risk globally.
4. The Valley Floor wetlands are the largest in the San Miguel river basin. They are a critical component of the ecosystem. They store and meter water flow derived from below-ground aquifers and spring floods, provide habitat for flora and fauna, and improve water quality for the river and for human consumption. Any changes to the Valley Floor and riparian areas associated with further development may compromise these benefits.
5. Plant life on the Valley Floor includes many relict species and a mix of species assemblages. Three of the six species considered at risk of extinction by the Colorado Natural Heritage Program are found in the vicinity of Telluride. A fourth occurs in fens and may be present in those on the Valley Floor.
6. Invertebrates, the foundation of aquatic and terrestrial food webs, are diverse on the Valley Floor. SEI focussed field surveys on butterflies and moths because of their importance as indicators of ecological health and biodiversity.
Surveys in 2000 and 2001 yielded at least five new moth species and a new genus, as well as several new county records for moths, butterflies, and other invertebrates. This was important news for science and for the community.
In 2001, SEI recorded 93 moth and 28 butterfly species. Mathematical calculations indicate that additional species remain to be found.
7. A comparison of the 2001 current moth survey with one carried out on the Valley Floor in 1976 indicates a strong overlap in species, which suggests that the Valley Floor has retained biological integrity and that these species may be restricted to this habitat.
8. The bog violet, Viola nephrophylla, is abundant on the Valley Floor. It is host to the rare Nokomis fritillary butterfly, first discovered on Mt. Sneffels and previous candidate for listing under the Federal Endangered Species Act (ESA). The Valley Floor, therefore, may provide an ideal habitat for this imperiled species. Multiple-year surveys are needed to establish if the species is present or could be reintroduced to the area.
9. The Valley Floor is also possible habitat for two threatened or endangered species, the Southwestern willow flycatcher and the boreal toad.
The Southwestern willow flycatcher (a bird species) breeds in riparian habitats generally characterized by willows or other shrubs. Only 109 breeding sites for the species are known in the US and one is in the San Miguel watershed. The discovery of an abandoned nest, identified by a bird biologist as a potential flycatcher nest, on public lands on the Valley Floor, and the suitability of the site for the willow flycatcher strengthen the likelihood of its presence.
The boreal toad is less likely to be present because of mining pollution, but the habitat provides a potential restoration/reintroduction site for the species.
10. Activities that change water flow and water quality could affect downstream fish populations, including the Colorado River cutthroat trout in the area and possibly the endangered Colorado River pikeminnow.
11. The Valley Floor retains strong biological integrity but has been degraded by human activities, some of which continue to have adverse impacts. Development, mine tailings, overgrazing, channelization of the river, water runoff, and recreational use all affect the ecosystem.
Conclusions and Recommendations
Overall, it is essential to take an ecosystem approach to issues surrounding the Valley Floor.
1. The conservation and restoration of sensitive river, riparian, willow, and wetland habitat is key. Development in these areas, particularly on the south side of the highway, is most likely to interrupt wetland and riverine habitats and processes. Development on the north side of the highway is less likely to have severe impacts, but subsurface flow must not be disrupted.
2. Despite human activities, the river is in good condition and has strong potential for restoration, especially for fish habitat. Gravel size, flow patterns, and riparian banks are ideal for trout. Restoring the riverís original pathway is recommended. Substrate and riparian restoration in adjacent stretches of the river appear to have been successful, which leads to optimism regarding our recommendation.
3. It is uncertain at this stage whether metal-contaminated sediments on the Valley Floor should be removed or left in place. Additional work is needed on the nature of the sediments and the potential to release more toxins into the river and wetlands if they are disturbed.
4. Although some grazing can be beneficial for biodiversity in that it maintains host plants for rare invertebrates, overgrazing reduces diversity. Any grazing activities must be managed and must include restoration; e.g., removal of invasive thistles spread by grazing.
5. Any future land use plans should consider impacts from recreational activities and must include refuge zones for plant and aquatic life.
6. The uniqueness of the Valley Floor ecosystem is an asset to the community not only because of its biological importance, but also because of historical and cultural connotations. The link with the writer and lepidopterist Vladimir Nabokov, who spent time in the area and considered it one of the four most important sites for butterflies in the U.S., should be explored for educational purposes and to promote the restoration of the habitat.
7. Ecosystems do not understand property lines. Habitats on the Valley Floor are affected by activities upstream and in adjacent areas as well as by those on the Valley Floor proper. Pollutant and sediment load from off-site activities damage the on-site habitat.
8. Several rare, threatened, or endangered species have been or may be found on the Valley Floor, and the Endangered Species Act has been frequently and successfully used to protect species and their habitats. The ESA prohibits any action that will harm, harass, or kill an endangered species.
If a listed species is found to occupy the habitat, then development requires negotiations between the landowner, US Fish and Wildlife, and the National Marine Fisheries Service. These negotiations may result in a Habitat Conservation Plan. This process, however, can be lengthy and costly and can polarize the community.
Therefore, ESA should not be taken lightly or misused in the effort to protect ecosystems and the region.
The solution to this issue will require the stakeholders to show openness and creativity. A landscape ecosystem approach based on biological relevance rather than ownership boundaries and that takes an incentive-based approach is preferable for successful long term conservation.
This report advocates using the scientific information to set priorities and parameters. An ideal next step is for the stakeholders to sit down at the table, review the existing scientific information, and evaluate the options in light of the effect on the ecosystem