Information on this page was provided by our friends at the Blue River Watershed Group.
What is a watershed?A watershed is a basin-like landform defined by highpoints and ridgelines that descend into lower elevations and stream valleys. A watershed carries water “shed” from the land after rain falls and snow melts. Drop by drop, water is channeled into soils, groundwaters, creeks, and streams, making its way to larger rivers and eventually the sea. The important thing about watersheds is: what we do on the land affects water quality for all communities living downstream. Click here for interactive watershed activities.
Information on watersheds provided by Watershed Atlas.
What makes up the Blue River Watershed?The Blue River drains an area of about 680 square miles in the central Rocky Mountains, west of the continental divide in Colorado. The watershed drains northward, from elevations reaching 14,270 feet along the southeastern perimeter, to where it flows into the Colorado River south of Kremmling at an elevation of 7,400 feet.
Three major tributaries in the Blue River watershed come together at Dillon Reservoir forming the Upper Blue River watershed. These are the Snake River, the Blue River, and Ten Mile Creek. The lower Blue River watershed is approximately the same size as the upper Blue River watershed, and contributes approximately the same virgin yields, which average approximately 160,000 acre feet (af) per year. An acre foot is an acre of water one foot deep or 326,000 gallons.
Most of the total annual stream flow results from snow melt during the spring and early summer. Major snowfall typically occurs January through April. Thunderstorm activity produces significant, though short-lived, rainfall events in July and August. Stream flows above major water storage facilities have marked seasonal variability. Discharges from groundwater systems contribute about a quarter of the total surface water flow.
The Blue River watershed includes all of Summit County, which encompasses approximately 619 square miles. An additional 61 square miles lie within Grand County, and the very head of the Ten Mile basin lies within Lake County.
The major population centers within the Blue River watershed are the towns and unincorporated areas of Blue River, Breckenridge, Copper Mountain, Frisco, Keystone, Dillon and Silverthorne. The permanent resident population of Summit County in 2000 was 20,946 and the peak seasonal population was 121,496!
Generally, water in the Blue River watershed is of high quality. A portion of the Blue River below Dillon Reservoir has been designated as a gold medal fishery by the Division of Wildlife. Four segments have significantly impaired water quality due to impacts associated with historical hard rock mining.
The major water quality challenges include runoff from old mining areas, urban areas and construction activities, trans-basin diversions (which reduce dilution and flushing flows), nutrients from septic systems, and, to a smaller degree, municipal treatment systems.
How is the Blue River part of the Colorado River Basin?
Blue River FAQsThe 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 2013 is between 27,000 and 28,000. 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.
Dillon ReservoirFilm courtesy of Denver Water September 30, 2013
Green Mountain Reservoir