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U.S. GEOLOGICAL SURVEY
Scientific Investigations Report 2006–5323

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Description of Study Area

The City and Borough of Juneau, along Gastineau Channel in southeast Alaska (fig. 1), is Alaska’s capital and the largest population center in the southeastern part of the state. Duck and Jordan Creeks flow through the eastern side of Juneau’s Mendenhall Valley (fig. 2). Mendenhall Valley originates at the Mendenhall Glacier about 10 mi northwest of downtown Juneau. East Mendenhall Valley is a developed residential and commercial area with a population of 12,122 in 2001 (City and Borough of Juneau, Alaska, 2001, accessed March 2, 2006), or more than one-third of the City and Borough of Juneau population.

Duck and Jordan Creeks occupy adjacent drainage basins of 1.3 and 2.6 mi², respectively, east of the Mendenhall River and south of the Mendenhall Glacier. The streams’ headwaters lie along the forested eastern flanks of the valley, which rise abruptly to an elevation of over 2,900 ft at the summit of Thunder Mountain. Duck Creek first becomes channelized within the developed valley floor, where surrounding land elevations are about 60 ft. Jordan Creek originates on the east flank of the valley wall and flows through a narrow strip of undeveloped muskeg and spruce forest within the Tongass National Forest before emerging into developed areas upstream from Egan Drive.

The study area consists of channel and flood plain areas along Duck Creek and along the reaches of Jordan Creek where the two streams’ flood plains could merge. Specifically, the study area consists of the main stem of Duck Creek (fig. 3A), a short tributary to Duck Creek, termed Unnamed Tributary to Duck Creek in this report (fig. 3B), and the main stem of Jordan Creek (fig. 3C). The modeled reach of Duck Creek is 3.4 mi long, extending from 40 ft upstream from Taku Boulevard to 40 ft downstream from Radcliffe Road at the end of the Juneau International Airport runway. The modeled reach of Unnamed Tributary to Duck Creek is 0.3 mi long, extending from 220 ft downstream from Valley Boulevard to a pond upstream from McGinnis Drive. The modeled reach of Jordan Creek is 1.1 mi long, extending from 370 ft upstream from Egan Drive to 50 ft downstream from Crest Street, within the perimeter of the Juneau International Airport. An additional, unnamed tributary to Duck Creek near Nancy Street was included in the previous FIS as East Fork Duck Creek, but was omitted from the study area for this report. This tributary drains a highly engineered environment dominated by a series of ponds formed in former gravel pits.

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