3.16 WETLANDS

3.16.1 Existing Conditions

Due to the rural setting of the project, there are numerous wetlands in the study area. However, the wetlands are fairly limited in areal extent and diversity, and tend to be dominated by monocultures of cattails or reed canarygrass. Wetlands generally occur along Stevens Creek, Salt Creek and tributary streams, as well as in isolated depressions and impoundments throughout the watersheds. The wetlands and waterways are categorized into six major groups:

• Riverine wetlands within Salt Creek and Stevens Creek
• Forested wetlands along tributaries
• Scrub-Shrub wetlands along tributaries
• Emergent wetlands along tributaries
• Impounded wetlands along tributaries
• Emergent, Forested and Scrub-Shrub isolated wetlands in depressions

Additional information on wetlands in provided in the Wetlands Delineation Report in Appendix D.

3.16.2 Impacts of the Four Finalist Alternatives

Wetlands in the study area were delineated in July and August 1999 using the 1987 Corps of Engineers (Corps) Wetland Delineation Manual. The field survey included all potential wetland areas and stream crossings that had the potential to be affected by the four finalist beltway alternatives. Depending on the configuration and selection of an alignment, some of these wetlands will not be affected. Table 3.19 is a summary of the estimated wetlands impacts for each of the the project alternatives.

3.16.3 Proposed Mitigation

Mitigation has been proposed to replace the wetlands at a minimum ratio of 1:1 replacement-to-loss. Wetland mitigation sites may be located along the proposed project route at feasible sites, or may be located in the City of Lincoln's Wetland Mitigation Bank, currently under development.

3.16.4 No Build Alternative

The no build alternative will impact wetlands along all proposed roadway network improvements in the Future 1 and 20 Year Program.

3.16.5 Compliance with Executive Order 11990, Protection of Wetlands

The south and east beltways, a linear transportation project by definition, must provide expressway connectors in both east-west and north-south directions. Because of the location of Salt Creek in the south, and Stevens Creek in the east, there are no alternatives which completely avoid impacts to wetlands or waters of the United States. Although few wetlands remain in the study area and the wetlands have been avoided to the extent possible, the project will unavoidably impact some wetlands due to (1) the linear nature of the project, and (2) the project goal to follow half section lines to the extent possible to minimize impacts to agricultural production and landowners. With the proposed wetland mitigation, the project would conform to existing State (NDEQ) requirements for mitigation of wetland impacts. Since these wetlands would be mitigated in-kind at accepted replacement-to-loss ratios, there is minimal impact on the beneficial values of wetlands in the area.

3.17 WATER BODY MODIFICATION AND WILDLIFE

3.17.1 Existing Conditions

Water Bodies. The main bodies of water in the beltway study area are Salt Creek and Stevens Creek and their tributaries, along with the North Fork of the Little Nemaha River and an unnamed tributary of Wagon Train Lake. Other minor water features include scattered farm ponds.

Terrestrial Habitat. Typical mammals that utilize riparian habitat along the creeks include white-tailed deer, red fox, raccoon, muskrat, beaver, opossum, mink, cottontail rabbit, and fox squirrel. Common bird species are mallard, blue-winged teal, belted kingfisher, great blue-heron, ring-necked pheasant, bobwhite quail, blackbirds, sparrows and wrens. Typical reptiles and amphibians include snakes, turtles, salamanders, and frogs.

Aquatic Habitat. Typcial fish species in Salt Creek and Stevens Creek include bullheads, carp, sunfish, shiners, and minnows. Typical fish species in most of the smaller tributaries are limited to minnows and shiners.

SM-4 Alternative. SM-4 crosses the mainstem of Salt Creek between Saltillo Road and Bennet Road near 25^th Street. The floodplain is very broad at this location, nearly 1.6 km (1 mi) wide. The mainstem channel is deeply entrenched and has been subject to significant erosion. The channel overbanks are planted in commodity crops with a significant zone of riparian vegetation along each bank. SM-4 also crosses the Wagon Train tributary of Salt Creek between Saltillo Road and Bennet Road near 84^th Street. The floodplain at this location is narrow and the channel is incised. The channel overbanks are planted in commodity crops with riparian vegetation along the banks. The US 77 interchange also crosses a tributary of Salt Creek. The channel overbanks are planted in commodity crops with little to no zone of riparian vegetation along the banks.

EC-1 Alternative. EC-1 crosses the mainstem of Stevens Creek, two tributaries to Stevens Creek, and an unnamed tributary to Salt Creek. The mainstem crossing of Stevens Creek occurs between Adams Street and Holdrege Street. The floodplain is broad at this location and is generally perpendicular to the proposed route. The channel overbanks are planted in commodity crops with a significant zone of riparian vegetation along each bank. The tributary floodplains crossed by EC-1 are located in the upper and middle portions of the respective drainage basins. They are broad with incised channels generally varying from 0.6 to 0.9 m (2 or 3 ft) deep and twice as wide. The channel overbanks are planted in commodity crops with a narrow zone of riparian vegetation along each bank.

EM-1 Alternative. EM-1 crosses the mainstem of Stevens Creek in two locations, two tributaries to Stevens Creek, and two unnamed tributaries to Salt Creek. The two mainstem crossings of Stevens Creek occur near Yankee Hill Road and 120^th Streets, and between O and A Streets near the MoPac Trail bridge over Stevens Creek east of Walton. Near Yankee Hill Road, the channel is deep and narrow, approximately 2.4 m (8 ft) deep and wide, with near vertical slopes. Riparian vegetation occurs in a narrow strip along each bank. The floodplain is broad and parallel to the proposed route. Near Walton, the channel is deeply incised, approximately

4.9 to 5.5 m (16 to 18 ft) deep and about three times as wide with a bottom width of 3.7 to 4.3 m (12 to 14 ft). Riparian vegetation occurs along each bank varying from zero to 30 m (100 ft) wide. The flood plain is very flat and broad at this location and is crossed at approximately a 45-degree angle by the proposed route. The tributary floodplains crossed by EM-1 are located in the lower and middle reaches of the respective drainage basins. They are broad with deeply incised channels generally varying from 2.4 to 3.0 m (8 to 10 ft) deep and two to three times as wide. Some channels have developed intermediate benches. The channel overbanks are planted in commodity crops with a significant zone of riparian vegetation along each bank.

EF-1 Alternative. EF-1 crosses five tributaries to Stevens Creek and an unnamed tributary to Salt Creek; the route does not cross the Stevens Creek mainstem channel. The tributary floodplains crossed by EF-1 are located in the middle to lower reaches of the respective drainage basins. They are broad with incised channels generally varying from 1.5 to 1.8 m (5 to 6 ft) deep and two to three times as wide. The channel overbanks are planted in commodity crops with a significant zone of riparian vegetation along each bank.

3.17.2 Impacts of the Four Finalist Alternatives

The primary water body modifications will be construction of bridges and culverts at the stream crossings. In general, the structures would cause no adverse long-term modification of water bodies, and would have no adverse impacts on wildlife that utilize the waterbodies-other than a minor loss of riparian habitat where it is currently present. The primary negative impacts would be temporary disturbance of wildlife, and temporay impact to aquatic habitat from increases in turbidity and total suspended solids during bridge construction. Good construction practices should keep suspended sediments at acceptable levels. Temporary construction impacts to surface waters are considered minor and can be minimized through use of temporary and permanent erosion control. Any riprap that may be used in embankment and pier protection for the new bridges would provide a new stable substrate for periphyton and macroinvertebrate colonization, thereby increasing the availability of food for fish in the area.

A list of the structures for each beltway alternative is provided in Table 3.20. Major culverts were defined as those costing upwards of $250,000. Additional minor bridges or major culverts may be required to accommodate the emergency spillways from the LPSNRD dam sites near the beltway alignments.

3.17.3 Proposed Mitigation

Mitigation measures will be implemented for construction-related erosion and sedimentation control and include, as appropriate, dikes, dams, sediment basins, fiber mats, temporary and permanent seeding, straw mulch, plastic liners, slope drains, and other devices which would intercept and trap transported sediments during construction. In addition, the project will require a National Pollution Discharge Elimination System (NPDES) permit from NDEQ which is needed for all sites greater than 2 ha (5 ac) in size. The permit will require incorporation of erosion and sedimentation control measures during construction.

3.17.4 No Build Alternative

The no action alternative would avoid all temporary adverse impacts to waterbodies and associated wildlife from construction of bridges and culverts, other than that required for construction of the proposed future roadway network improvements.