Red Mountain Creek, Ouray County, Colorado

KNOW YOUR STREAMFLOW: Dissolved and total particles

Dissolved and total particles become suspended in a stream in a variety of ways such as natural erosion, acid rock drainage from mines, acid runoff over mine waste, and runoff from streets and highways. Other ways include effluent from sewage treatment plants, return flow from irrigation, and groundwater from springs and irrigation pumping. Both suspended solids and dissolved minerals can produce a variety of colors in the Uncompahgre River, most commonly browns (from soil), yellows, oranges, and reds (from metal compounds). 

In addition to visual impacts, metals, nutrients, and bacteria can have harmful effects on aquatic life and humans when they reach certain concentrations. Dissolved substances, like metals, can be present even when a stream looks clear and pristine. The concentration of a substance is the amount of its mass in a specified volume of water, so concentrations in a stream will change as the mass entering a stream changes and the volume of water (streamflow) changes.

Various water sources with dissolved and total particles: figure 1- Red Mountain mine adit; figure 2- Red Mountain Creek north of Crystal Reservoir; figure 3- Sneffels Creek in 2013, contaminated by mine tailings; figure 4- Ridgway Reservoir, after the Ouray Hydrodam sediment release.