Botany and Wetlands Study Report - McMillen, LLC

Botany and Wetlands Study ReportSoutheast Alaska Power Agency4.3.2 Bog St. John’s‐wort (Hypericum anagalloides Cham. & Schltdl.)Bog St. John’s‐wort is a small, perennial herb in the St. John’s‐wort family with matted stems andtiny, orangish‐yellow flowers. Habitat for this species includes a variety of moist to wet habitats.It is widely distributed across western North America (USDA NRCS 2012). The most northernpopulation previously documented is on McCauley Island in British Columbia, approximately 160miles south of Swan Lake.In the analysis area, two populations of bog St. John’s‐wort were observed. One population wasgrowing on a large floating log mat on open water in Swan Lake. The other was in the vicinity ofLost Creek. Although this species was observed twice in the analysis area, it was not collected.Direct and Indirect ImpactsThe proposed project would likely have direct effects on the bog St. John’s‐wort population nearLost Creek because some of the plants would be inundated by the 15‐foot dam pool raise. Thepopulation on the floating log mat would likely keep floating amidst the 15‐foot dam pool raise.Indirect effects to plants not inundated are also possible, potentially occurring as a result of lightlevel changes or water table level changes resulting from inundation. The presence of additionalundetected populations in the analysis area is likely because suitable habitat for this species iscommon in the analysis area and the analysis area was not completely surveyed for this species.4.4 Management Requirements and Mitigation Measures for Sensitiveand Rare PlantsAs most populations of rare plants observed in the analysis area would likely be inundated withrising reservoir levels, avoidance of impacts to these populations is not feasible. The followingmeasures are suggested mitigation measures for the impacts to rare species in the analysis area.Final mitigation measures would be developed in collaboration with Forest Servicebotanist/ecologists.Conduct pre‐construction surveys for rare plants in areas of potential habitat in theanalysis area to obtain population estimates for each rare plant species observed.If feasible, populations of rare plants will be transplanted, or seeds will be collected andsown, in suitable areas above the inundation zone. These transplanted and/or seededpopulations will be monitored for 5 years to determine if they are successfully becomingestablished and to compare population estimates of transplanted populations withpopulation estimates of impacted populations.If transplantation or relocation is not possible, conserve and monitor existingpopulations, outside of the inundation zone, of the rare plant species that will beimpacted by inundation.Swan Lake Hydroelectric Project January 2013FERC Project No. 2911 Page 26 Version: Agency Review