Blue River Watershed Fast Facts

  • The Blue River Watershed (BRW) is located in the Colorado Rocky Mountains, west of the Continental Divide. It encompasses about 680 square miles in three counties including, from south to north:
    • the source (headwaters) of the Blue River, from the very head of the Ten Mile Basin in Lake County,
    • the entire 619 square miles of Summit County,
    • 61 square miles in Grand County.
  • Three major tributaries converge at Dillon Reservoir to form the upper Blue River watershed:
    • the Snake River (from the east)
    • the Blue River (from the south)
    • Tenmile Creek (from the west).
  • The watershed drains from peaks higher than 14,000 feet in the south to 7,400 feet, where it flows into the Colorado River near Kremmling in the north.
  • The upper and lower regions of the watershed each yield approximately 160,000 acre feet (af) of water per year (an acre foot is an acre of water one foot deep, or 325,851 gallons).
  • Major snowfall typically occurs January through April. Most of the annual stream flow results from snow melt during the spring and early summer. Thunderstorms produce significant rainfall in July and August. Groundwater return flows to streams contribute about a quarter of the total surface flow.
  • The permanent year-round population of Summit County as of 2008 is between 28,000 and 29,000. The resident population has increased an average of 7% a year for the last nine years. During peak tourist visits (typically around the Christmas/New Year and Spring Break) the population can increase to over 150,000. This creates an added burden on our drinking water and wastewater providers.