FS0018X Feasibility Study 11/01

• Contract/PO #: FS0018X
• Contractor Name: Sterling, City of
• Contract Type: Loan
• Loan Projects - Doc Type: Feasibility Study

HWY 6 and the BNRR/UPRR embankments are major obstructions, which divert
Pawnee Creek flood flows from the main channel towards the City of Sterling. The
Town of Atwood is located near the natural floodplain of Pawnee Creek; however, the
City of Sterling is not. The flood flows from Pawnee Creek into Sterling are mainly due
to the manmade embankments, which act as diversion structures, since flood flows on
Pawnee Creek are not entirely able to pass directly to the South Platte River through the
existing bridges or over the embankments. When flows are high enough, a portion of the
flow is diverted to Sterling along the northwest side of the highway and railroad
embankments. This situation is known as the "Pawnee Overflow". Reference is made to
Figure 2,which presents a vicinity map of the area.
City of Sterling Contacts:
Mayor Bill Finch
City Manager Randy Gustafson
Director of Public Works Joe Kiolbasa
City of Sterling
421 North 4th Street
Box 4000
Sterling, CO 80751
Phone: [phone]
Fax: [phone]
III PROJECT SERVICE AREA
Study Area
The project area is located in northeastern Colorado. The City of Sterling and the project
area are within Logan County, which is approximately 120 miles northeast of Denver.
The watershed of interest is the Pawnee Creek Basin, which is within the South Platte
River Basin. The basin is a left bank tributary with its confluence with the South Platte
River located upstream of the City limits of Sterling, Colorado. Major tributaries to
Pawnee Creek include: Raymer Creek; South Pawnee Creek with its tributary Wildhorse
Creek; North Pawnee Creek with its tributary Igo Creek; Cottonwood Creek; Horsetail
Creek; and Spring Creek. These creeks are basically intermittent with running water in
the lower reaches.
Predominate topographic features of the basin include the Pawnee Buttes in the upper
reaches of the basin. The basin's drainage area is approximately 645 square miles.
Elevations in the basin range from approximately 5,400 feet to 3,980 feet. The watershed
is mainly native grass with localized regions of cultivated agriculture. Soils are
predominately barns and clay loams, with sandstone, shale and siltstone outcroppings.
Hydrologic curve numbers are in the range of 77 to 79 with the primary vegetation being
native range with some winter wheat and a significant amount of irrigated cropland in the
lower part of the basin.
4