RCMAP - Lake Fork at Gateview, Colorado

Science Center Objects

The U.S. Geological Survey was engaged in a program to monitor and assess the long-term geomorphic behavior of selected river and stream reaches that previously had undergone some physical modification.  These modifications included natural channel adjustments to floods as well as intentional channel reconfigurations to alter the function or appearance of a river reach.

Land use in the Lake Fork Valley is predominantly agricultural (hay meadows and livestock grazing). Aerial photography from 1977 and onsite reconnaissance in 1992 and 1998 indicated that segments of the river channel had been artificially straightened. Other segments were braided and prone to bank erosion and lateral shifting. Prior to reconfiguration, the reach near the Gateview gage was characterized by a wide, shallow channel with a streambed composed of gravel, cobbles, and boulders. Onsite reconnaissance and land-owner interviews in 1998 indicated that some segments of the channel were laterally restricted by an engineered levee and possibly dredged over a period of years.

Lake Fork at Gateview, August 2000

Looking upstream from bridge to constructed alternate bars. Discharge: 89 cfs

A 2-mile reach of the Lake Fork was reconfigured in late 1997 to mitigate past problems associated with flooding and gravel deposition on the flood plain, and to improve the trout fishery. The channel modifications included:

  1. deepening of the channel by streambed excavation,
  2. slight increases in sinuosity by constructing new cobble alternate bars within the former bank-to-bank channel area,
  3. reduction of flow width and creation of streambank protection through addition of coarse sediment and tree-root wads to formerly vertical banks
  4. addition of large boulders as streambed roughness elements to improve fish habitat, and
  5. construction of several grade-control and flow-directing structures composed of large boulders. The boulder structures placed in the stream were designed to re-direct high-velocity flow and to facilitate bedload transport through the reach.

A 2,500 ft. reach of the Lake Fork was monumented and surveyed by the USGS in September 1998 and again in August 2000. Permanent reference marks were installed for vertical and horizontal control. The reference-mark locations (latitude and longitude) were determined with a global positioning system (GPS) receiver to facilitate replication of the survey at a future date. The survey consisted of longitudinal profiles of the streambanks, terraces, and the water surface at a streamflows of approximately 220 and 88 ft3/s. Nine channel cross sections were surveyed in the study reach. Cross sections were selected that represented the range of channel geometry in the reach or that were in locations likely to exhibit change should future adjustments occur in cross-section dimensions. The cross section endpoints were established on a relatively stable surface, monumented with rebar, and located with a GPS receiver.

Location:

SE 1/4 of the NE 1/4 of Sec. 29, T47N, R3W, Gunnison County. Streamflow gaging station 09124500 Lake Fork at Gateview is in the monitoring reach, located at Lat 38o17' 56", Long 107o13' 46", on left bank 25 ft downstream from private bridge, 0.2 miles upstream from Indian Creek, elevation 7,519 ft.

Streamflow Data:

Current streamflow: USGS 09124500 Lake Fork at Gateview

View peak streamflow: USGS 09124500 Lake Fork at Gateview

 

Photographic History

Sediment Surveys

See Sediment Distribution Charts for Lake Fork at Gateview, Colorado

Channel Surveys

See Cross Section Data for sites on Lake Fork at Gateview, Colorado

Additional data regarding reference mark locations