Animas River

Animas River
Name	Animas River
Source	San Juan Mountains
Mouth	San Juan River
Country	United States
State	Colorado; New Mexico
Length	126mi
Basin	Colorado River Basin

Animas River is a tributary of the San Juan River that flows from the San Juan Mountains in Colorado through the city of Durango to join the San Juan River near Farmington. The river traverses alpine headwaters, steep canyons, and high-desert valleys, intersecting landscapes and jurisdictions including San Juan County, Colorado, La Plata County, and San Juan County, New Mexico. It is entwined with regional water management projects, historic mining districts, and contemporary conservation efforts involving federal, state, and tribal entities such as the United States Forest Service, Bureau of Land Management, and the Southern Ute Indian Tribe.

Course and Geography

The river originates in the Weminuche Wilderness and Needle Mountains of the San Juan Mountains, flowing southwest past Silverton, Colorado, then through the Animas Forks region, descending into the Animas Valley and entering Durango where it is joined by tributaries including the Florida River and the Hermosa Creek. From Durango it continues south into the high desert of the Colorado Plateau and crosses the Colorado–New Mexico border to join the San Juan River near Farmington and the Navajo Nation. Major geographic features along the course include Purgatory Creek, Coal Bank Pass, Vallecitos Creek, and the Animas La Plata Project reservoirs and diversions associated with the Bureau of Reclamation and the U.S. Department of the Interior. The watershed lies within the larger Colorado River Basin and connects to interstate water systems governed by agreements like the Colorado River Compact.

Hydrology and Water Quality

Flow regimes are influenced by snowmelt from the San Juan Mountains and contributions from alpine lakes such as those in the Weminuche Wilderness, producing seasonal discharge variability documented by gauges maintained by the United States Geological Survey. Historical and ongoing impacts from hard-rock mining in the Silverton and Idarado Mine districts have affected water chemistry, with legacy metals including copper, zinc, lead, and cadmium studied by agencies including the Environmental Protection Agency and the Colorado Department of Public Health and Environment. Water rights and allocation in the watershed intersect with legal frameworks such as the Winters Doctrine and compacts like the Colorado River Compact, and projects such as the Animas La Plata Project alter base flows for municipal and tribal water supplies. Floods, droughts, and anthropogenic alterations are monitored in coordination with the National Weather Service and the Bureau of Reclamation.

History and Human Use

Indigenous presence in the basin is associated with groups including the Ute Mountain Ute Tribe and the Southern Ute Indian Tribe, with traditional uses predating European exploration by centuries. Spanish explorers and settlers from New Spain traversed the region, later followed by Anglo-American miners during the Colorado Gold Rush and the development of silver and base-metal mining centered on Silverton, Colorado, Ouray, and the San Juan Mountain mining district. Transportation corridors such as the Durango and Silverton Narrow Gauge Railroad and highways like U.S. Route 550 and U.S. Route 160 trace the river corridor. Federal policies including the General Mining Act of 1872 and conservation initiatives by the National Park Service and the United States Forest Service affected land tenure, resource extraction, and recreation. Contemporary water projects, negotiations, and settlements have involved entities like the Animas-La Plata Project, U.S. Bureau of Reclamation, and tribal governments addressing water rights and supply.

Ecology and Wildlife

Riparian habitats along the river support assemblages of native flora such as Gambel oak stands and willow communities, and fauna including native trout populations like Colorado River cutthroat trout remnants and introduced species such as rainbow trout and brown trout. Amphibians, avian species including belted kingfisher and great blue heron, and mammals such as beaver and river otter are found in riparian corridors managed by agencies including the Colorado Parks and Wildlife and the New Mexico Department of Game and Fish. Aquatic invertebrate communities serve as indicators of ecological condition in studies by universities such as Colorado State University and University of Colorado Boulder. Habitat restoration projects have engaged conservation NGOs including The Nature Conservancy and regional watershed coalitions.

Recreation and Conservation

The river corridor provides recreation ranging from whitewater boating on runs near Durango and Silverton to fly-fishing celebrated by outfitters, and hiking in public lands such as the San Juan National Forest and Wilderness Areas including the Lizard Head Wilderness. Tourism hubs like Purgatory Resort and the historic Durango and Silverton Narrow Gauge Railroad contribute to the outdoor economy alongside outfitters, guides, and conservation groups like the San Juan Citizens Alliance. Conservation designations and land management plans involve the Bureau of Land Management, United States Forest Service, and state parks such as Pine River State Wildlife Area and collaboration with tribal partners like the Ute Mountain Ute Tribe. River stewardship initiatives address invasive species management, streamflow enhancement, and public education through entities such as the Animas River Stakeholders Group and regional watershed councils.

Environmental Incidents and Restoration

Notable contamination events include drainage from historic mines in the San Juan Mountains and the 2015 release of mine wastewater from the Gold King Mine, which mobilized metals and sediments downstream, prompting responses from the Environmental Protection Agency, the U.S. Department of the Interior, and state agencies including the Colorado Department of Public Health and Environment and the New Mexico Environment Department. Remediation and restoration efforts have included Superfund evaluations, work by the Environmental Protection Agency and the U.S. Forest Service, and cooperative cleanup and monitoring involving the State of Colorado, State of New Mexico, tribal governments, and nonprofit organizations like American Rivers. Long-term restoration emphasizes source control at mine sites such as Bonita Peak Mining District, passive treatment systems, engineered diversions, and watershed-scale planning coordinated with institutions like the U.S. Geological Survey and academic partners including University of New Mexico.

Category:Rivers of Colorado Category:Rivers of New Mexico Category:Tributaries of the San Juan River (Colorado River tributary)