24 September 2004

TO: Kent Doughty, EES Consulting

FROM: Devin Malkin, DTA

RE: Packwood Lake Project aquatic/emergent weed survey

Kent,

On 23 September 2004 I surveyed areas associated with the Packwood Lake Hydroelectric Project for aquatic and emergent noxious weeds. Per your request, this memo briefly describes the survey methods and results; a more detailed project report will follow before 30 November 2004.

The survey area included 1) Lake Creek from its confluence with the Cowlitz River upstream to the Forest Service property boundary at approximately RM 0.7; 2) the Packwood Lake Project tailrace and stilling basin. I defined target species as those plants listed as noxious by the Lewis County Noxious Weed Control Board that have also been assigned a Wetland Indicator Status rating of FACW or OBL by the US Fish and Wildlife Service. Although the focus of this work was aquatic and emergent target species, all plants listed as noxious weeds were noted, along with general habitat observations.

No target species were observed in the survey boundary. Most of the survey area represents poor habitat for aquatic and emergent plants, as neither Lake Creek nor the tailrace proper include ponded areas, slow-moving waters or low-gradient shorelines. However, at Hall Creek the tailrace includes a 360 foot flume that crosses substantial wetland and open water habitats. This area is dominated by Phalaris arundinacea (reed canarygrass), a class C weed in Washington that is not adopted by the Lewis County Noxious Weed Control Board, and not managed in the county. Small open water patches traversed by the tailrace flume support Elodea canadensis (Canadian waterweed), a native aquatic species. The tailrace flume crossing this area is largely devoid of vegetation.

The remainder of the tailrace is a concrete-lined channel supporting little vegetation, although the exotic upland grasses Dactylis glomerata (orchardgrass) and Phleum pretense (timothy) are common on its upper edges. Upland species along the constructed bank include noxious weeds typical of disturbed habitats, including Cytisus scoparius (Scotch broom), Hypochaeris radicata (cat’s ear), and Hypericum perforatum (St. John’s wort). In addition, a small (5 by 5 foot) patch of Polygonum cuspidatum (Japanese knotweed) occurs on the outside cutbank of the tailrace road, in an area disturbed by development. This target species is listed as Class B-Select in Lewis County, and is a high priority for management, but the occurrence is somewhat outside the study area boundary. Beyond the downstream end of the tailrace proper (i.e., the concrete channel), the banks of some riparian habitats support Geranium robertanium, a mesic upland species listed as Class B by the Washington State Noxious Weed Control Board but not adopted by Lewis County.

Lake Creek is a moderate-gradient stream supporting no aquatic macrophytes, few emergent plants, and no target species. (A reported occurrence of Polygonum cuspidatum at the confluence of Lake Creek and the Cowlitz River was not observed.) While in most respects typical of western Washington stream courses, the riparian zone of Lake Creek is notable for the overwhelming dominance of Geranium robertanium in the herbaceous layer. This plant appears to have undergone a dramatic expansion in recent years, likely to the detriment of native species.