Condit Dam Removal Condit Dam Removal - Access Washington

Condit Dam Hydroelectric Project
Final Supplemental EIS
and contain one edge that is lake fringe. Delta wetlands total 0.9 acre in area. Wetlands 5, 8,
and 10 are rated as Category II and Wetland 12 along Condit Creek is rated as Category III.
Wetland 26 was identified by URS staff during a May 30, 2005 site visit to review recent
changes in the proposed deconstruction plan. It is shown on Figure 4.4-2. This 4-foot-wide
by 45-foot-long (0.004 acre) roadside wetland is located about 1,000 feet southeast of Condit
Dam directly west of Powerhouse Road. This palustrine emergent slope wetland is watered
by a seep that appears to receive seasonal groundwater discharge fed by an irrigated orchard
about 100 feet upslope on the opposite side of Powerhouse Road. Water moves through the
small wetland and continues across the surface of the existing dam access road before
infiltrating underground further down the slope. In the winter there may be more flow
causing the downslope section to be an ephemeral stream for a short distance, but there are
no wetland characteristics beyond the area delineated as Wetland 26. Soils were saturated to
the surface with free water at 10 inches in the soil pit during the May 30, 2005 site visit. The
dark brown (10YR 3/3) A soil horizon to 9 inches over a deep dark grayish brown (10YR
3/2) B soil horizon generally matches the Hood loam soil series identified for this site in the
Natural Resources Conservation Service (NRCS) Soil Survey of Klickitat County (CH2M
Hill 2003, Haagen 1990). Soils are possibly relic disturbed or fill material from the adjacent
two roadways. Dominant vegetation includes the herbaceous giant horsetail (Equisetum
telmateia/FACW) and bluejoint reedgrass (Calamagrostis canadensis/FACW+). Other
species present include cleavers (Galium aparine/FACU), small fruited bulrush (Scirpus
microcarpus/OBL), and creeping bentgrass (Agrostis stolonifera/FAC). Wetland 26 is rated
as a Category IV wetland. The wetland data sheet is available in Appendix D.
4.4.2 Impacts
Pre-Dam Removal Activities
Wetland 12 would be partially filled for construction of a haul road between the eastern end
of the dam and the proposed concrete storage/disposal area. A culvert is anticipated to be
placed within the wetland at the Condit Creek crossing. At the probable crossing location,
the delta wetland is up to 25 feet wide on each side of the creek where it meets the lake.
Because the road would need to turn just past the crossing, it is presumed that a culvert 40
feet long would be required. Up to 1,000 square feet of wetland on each side of the Condit
Creek crossing could be filled.
At Wetland 21, a maximum of 875 square feet of wetland would be filled in order to
complete the concrete storage/disposal area haul road, if it follows the old road route at this
point. Since this would include the point of discharge of the seep that feeds the wetland, it is
presumed that the seep would be culverted to allow it to continue supplying water to the
downslope part of the wetland. It appears that the road could be rerouted at this location to
avoid part of the wetland and put the road farther from a cabin. If that is done, the wetland
impact is estimated to be about 440 square feet.
Wetland 26 would be filled during expansion of the access road from Powerhouse Road to
the lower side of the dam for construction vehicles and machinery. It is presumed that all of
Wetland 26 (180 square feet) would be excavated and/or filled in order to build the access
4.4-5