FLOOD03617

• County: Summit
• Community: Silverthorne
• Basin: Colorado Mainstem
• Title: FIS - Silverthorne
• Date: 8/9/2001
• Prepared For: Silverthorne
• Prepared By: FEMA
• Floodplain - Doc Type: Current FEMA Regulatory Floodplain Information

For the restudy, community base map selection and the identification of streams requiring
detailed study was accomplished in a meeting attended by representatives from FEMA, the
study contractor, the Colorado Water Conservation Board, and the Town of Silverthorne
on February 6, 1997. Summit county also provided assistance in gathering information
for this report.

During the course of the study, hydrologic procedures, flood elevations, flood boundaries,
and floodway delineations were reviewed with officials of the Colorado Water
Conservation Board (Reference I) and FEMA.

The results of the restudy were reviewed at the final Consultation Coordination Officer
meeting held on June 22, 2000, and attended by representatives of FEMA, the State of
Colorado, and the community. All problems raised at that meeting have been addressed
in this study.

2,0 AREA STUDIED

2.1 Scope of Study

This Flood Insurance Study covers the unincorporated areas of the Town of Silverthorne,
Summit County, Colorado.

For the original study, the following steams were studied in detail: Blue River within the
corporate limits; Straight Creek, from the upstream corporate limits to its confluence with
the Blue River; and, Willow Creek, from west of the upstream corporate limits to its
confluence with the Blue River (beyond the downstream corporate limits).

For the restudy, all of the flooding sources described above were entirely restudied by
detailed methods.

The areas studied by detailed methods were selected with priority given to all known flood
hazards and areas of projected development or proposed construction through 1998.

2.2 Community Description

The Town of Silverthorne is in the center of Summit County, in north-central Colorado,
approximately 70 miles west of Denver, on Interstate Highway 70. Silverthorne lies at an
elevation of 8,790 feet, just downstream of the Dillon Reservoir on the Blue River.
Incorporated in 1961, Silverthorne began as a residential area approximately 2 miles north
of the old Town of Dillon. State Highway 9 generally parallels the Blue River and
provides access to Interstate Highway 70; U.S. Route 6, just south of the town; and Green
Mountain Reservoir and Kremmling to the north.

The Blue River flows north through the town and is the principal river in Summit County,
having a drainage area of 377 square miles near the north end of town at Willow Creek.
The discharge of the river through Silverthorne is regulated by the Dillon Reservoir. The
average annual peak discharge downstream of the reservoir is approximately 1,103 cubic
feet per second (cfs) (Reference 2).

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