Animas River

About the Animas River

• The Animas River is born from snowmelt high in the San Juan Mountains of southwestern Colorado, descending nearly 6,000 feet as it passes through Silverton and Durango, Colorado, then Aztec, New Mexico, before joining the San Juan River at Farmington.1
• On August 5, 2015, an EPA crew working at the Gold King Mine near Silverton breached a plug holding back contaminated water, releasing about three million gallons of acidic mine wastewater (by USGS stream-gauge calculation) that carried heavy metals down the Animas. The plume passed through Colorado, New Mexico and the Navajo Nation and into Utah.23
• In New Mexico the river runs past Aztec, where Aztec Ruins National Monument sits along its east bank on the site of an ancestral Puebloan community of multi-story structures, and where the Farmers Irrigation District draws Animas water for landowners between Aztec and Flora Vista.45

This report follows 123 miles (198 km) of the Animas River, all within the Animas watershed segment. At the lower end of the report the river drains about 1,347 square miles. Downstream of the mapped reach it flows into the San Juan River. Named tributaries joining it here include the Florida River, Hermosa Creek, Cascade Creek, Lightner Creek and Junction Creek. Largest urban areas near it: Farmington, Durango and Aztec. 10 gauges with at least 26 weeks of daily flow cover 1897 to 2026.

From the archive: NHDPlus river network, WBD watersheds, NHD waterbodies, TIGER urban areas and the report's gauges.

From the headwaters down

Each watershed segment in order, with last week's flow rated against the same week in 1991–2020.

1. 1

   Segment 1: Animas

   2,428 cfs last week much above normal.

   Towns: Farmington, Durango, Aztec.

   Water 3.7 °C at Animas River At Farmington, NM. Median conductance 608 µS/cm in the 2020s. Rain over the last 3 months: 228% of normal.

Culture

• Aztec Ruins National Monument, bounded on the east by the Animas River, preserves an extensive community of multi-story structures built by 11th- to 13th-century ancestors of today's Pueblo peoples, who used irrigation ditches drawing river water for crop cultivation.4
• The Lower Animas Ditch, a National Register-listed irrigation ditch put into service on the Animas River near Aztec in 1878, was built using earthen-ditch irrigation techniques that Anglo-American homesteaders learned from Hispanic-American settlers of southern Colorado, and its winding path helped shape Aztec's historic town plan.6

Habitat

• At Aztec Ruins National Monument, riparian vegetation of cottonwoods, willows and Russian olive lines the Animas River's lowest-elevation stretch and provides habitat for a variety of birds and other animals.4
• A four-mile stretch of the Animas through Durango, Colorado gained the state's Gold Medal trout-fishery designation in 1996, but a Colorado Parks and Wildlife biologist says heavy metals leaching from abandoned mines near Silverton, high water temperatures and sediment loading now keep the river's trout from reproducing naturally, so the fishery depends on stocking.7
• Five years after the Gold King Mine spill, the stretch of the Animas between Silverton and Bakers Bridge (about 15 miles above Durango) was virtually devoid of aquatic life, and fish in the river through Durango were still unable to reproduce because of ongoing heavy-metal contamination from inactive mines.8
• In New Mexico, fish sampled from the Animas and San Juan rivers after the 2015 spill included both trout and catfish.9

Reservoirs

From the archive: National Inventory of Dams (USACE) and the reservoir registry.

Water users

• The Farmers Irrigation District draws water from the Animas River north of Aztec to serve landowners down to Farmington Lake in Flora Vista, New Mexico, through a ditch system begun in 1892 and extended in 1907; San Juan County made it a special irrigation district with taxing authority in 1954.5
• The Bureau of Reclamation's Animas-La Plata Project, built to fulfill a 1986 Colorado Ute Indian water rights settlement, stores Animas River water at Lake Nighthorse behind Ridges Basin Dam and delivers it to the Colorado Ute Tribes (including the Southern Ute Indian Tribe), the Navajo Nation, the City of Farmington and other water users in southwestern Colorado and northwestern New Mexico, including through the Navajo Nation Municipal Pipeline.10
• The 2015 Gold King Mine spill sent an EPA-estimated one-to-three-million-gallon plume of acidic, metal-laden mine wastewater down the Animas and into the San Juan River, with EPA and other responders sampling water and sediment across Colorado, the Southern Ute and Ute Mountain Ute reservations, New Mexico, the Navajo Nation and Utah; the New Mexico Environment Department lifted its ban on private domestic wells on August 14, 2015, and on San Juan County's drinking water system supplied by the Animas and San Juan rivers on August 15.23
• EPA sampled water and sediment from the San Juan River in the Navajo Nation, and Navajo Nation President Russell Begaye directed that the Fruitland Irrigation canal — which delivers San Juan River water to three Navajo chapters — be reopened once the data showed water quality had returned to pre-spill conditions.11
• After the spill, New Mexico Game and Fish recommended catch-and-release fishing on the Animas and San Juan rivers, then lifted the recommendation after a Colorado lab tested tissue from 17 fish (5 catfish and 12 trout) and found metal levels within acceptable limits for human consumption, with the state committing to continued monitoring.9

Surface water withdrawn, 2020

In the counties this river crosses (San Juan): 412,312 acre-feet. County totals include other streams.

State Engineer, New Mexico Water Use by Categories 2020.

Irrigation districts and acequias

• Hammond Conservancy District (44,212 acres mapped)
• Farmers Irrigation District (5,072 acres mapped)

State Engineer's irrigation districts and acequia layers.

Public water systems beside the river

Northstar MDWCA, Farmington Water System, Flora Vista Mutual Domestic, Animas Valley Land & Water, Southside Mutual Domestic Water, Aztec Domestic Water System

State Engineer's public water systems layer (service areas within 2 km).