FLOOD09102

• County: Logan
• Community: Sterling
• Basin: South Patte
• Title: Sterling Flood Control Interceptor Channel Project
• Date: 4/1/2002
• Prepared For: Sterling
• Prepared By: URS
• Floodplain - Doc Type: Project

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SEmOITHREE Affected Environments and Environmental Consequences

would affect more than 500 feet of a stream, more than 3 acres of wetlands, or the stream flow is
greater than 5 cfs, an individual permit would be required (R. Flecher, USACE, personnel
communication, 1999). If the proposed project would affect resources less than those listed
above, a General Permit 26 would be required.

Also, the United States Fish and Wildlife Service (USFWS) National Wetland Inventory (NWI)
map and the Soil Survey map for Logan County were examined to determine the presence of
known wetlands in the project area.

3.10.1.1 Alternative 1- No Action

Since the No Action Alternative does not include any construction activities, it would have no
impact on wetlands.

3.10.1.2 Alternative 2 - Sterling Flood Control Interceptor Channel (Proposed
Action)

A wetland survey ofthe project area was conducted on November 1, 2001 within the project area
for Alternative 2. One wetland area along a side channel to the South Platte River was
delineated (ERO 2001). The wetland on the outfall of the South Platte River was classified as
palustrine and forested, scrub/shrub and intermittently flooded with open water (USFWS 1977).

Construction of the outfall along the side channel of the South Platte River would encroach on
the wetland area ofthe South Platte River. Approximately 0.5 acre of wetland would be
impacted at this location. The City of Sterling is in the process of obtaining a Section 404 Permit
from the US ACE. As part of the application, the City has identified wetland mitigation measures
that would be used to mitigate the identified impacts. Their proposed mitigation includes the
creation of a wetland north and adjacent to the proposed channel at the confluence with the South
Platte River. This wetland would be approximately 0.51 acre in size and would be located within
an area adjacent to existing riparian wetlands. Vegetation within the wetland mitigation site is a
mixture of native grasses and annual weeds. The creation of this wetland would include
stockpiling the topsoil from the existing wetland, then placing the stockpiles of wetland soils
uniformly over the bottom of the excavation. Willow stakes would be placed throughout the
mitigation site to promote the reestablishment of wetland vegetation. In addition, two
groundwater monitoring wells would be installed in the proposed wetland to verify that the post-
project water level is sufficient to sustain the wetland vegetation.

A public notice was published on February 5, 2002 by the USACE stating that Sterling has
applied for a Section 404 Permit. The USACE, in consultation with the Colorado Department of
Health, would also be responsible for 401 Certification prior to issuing the 404 Permit.

3.10.1.3 Alternative 3 -Improve Routing of Pawnee Creek Flood Flows

The general project area of Alternative 3 includes a wetland on the South Platte River near the
location where the drop structure would be constructed, downstream from Riverside Cemetery.
This wetland was classified as palustrine and forested with open water (USFWS 1997).

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