HYDROGEOLOGIC CHARACTERIZATION OF MOVING MOUNTAIN SPRING, DURANGO, COLORADO

Moving Mountain Spring is a non-thermal, cold-water spring located about 1.5 miles southeast of Durango, Colorado at the base of the Moving Mountain Landslide (UTM 4,124,625.8N, 245,490.6E, Zone 13S). The average discharge of the primary spring during the winter 2003 observation period was approximately one gallon per second. The spring issues from a construct of travertine into the Animas River near the contact between the Cretaceous Fruitland and Pictured Cliffs Formations. In the immediate vicinity of the spring, H₂S and CH₄ gas issue from the Animas River bed. The location of the spring is also significant because it may influence the stability of the landslide.

A study was launched to determine whether the source of the spring water was: 1) meteoric water from a local, upgradient source; 2) naturally diverted Animas River water reentering the river; or 3) connate or basin waters from the San Juan Basin. Physical and chemical characteristics of the spring water were compared to water samples from the Animas River and a deep well that tapped San Juan Basin water. All of the water samples were analyzed for TDS, pH, stable isotopes (dD and d¹⁸O), and selected dissolved ions (Fe, Mn, Mg). Chemical analyses were performed using Flame Emission, Atomic Absorption Spectrometry. Isotopic values were also compared to a previously established San Juan Basin data set, and the dissolved ion analyses were compared to a nearby coal-bed methane water data set.