Dames & Moore, 1999 - USDA Forest Service

4.1 PHYSICAL SETTING
4.0 PHYSICAL CHARACTERISTICS OF THE SITE
4.1.1 Geographic Setting and Topography
4.1.1.1 Lake Chelan Basin
Referring to Figure 4.1-1, the Lake Chelan basin is a glaciated valley situated in nortti-central Washington
State, on the east slope of the Cascade Mountains. The lake is the second deepest lake in the United
States, and the largest and deepest lake in Washington. The deepest portion of the lake is near its center;
the depth of the lake at this point based on sonar is 1,486 feet, or 453 meters. The length of the lake along
its principal axis is approximately 50 miles. During the summer months, the water level in the lake is
approximately 1,100 feet above sea level. The original elevation of the lake was reportedly raised 21 feet
in 1928 by a dam, which is still in place, at the southernmost end of the lake at the town of Chelan. There
are a number of tributaries entering the lake; the major drainages are Railroad Creek on the west, Prince
Creek on the east, and the Stehekin River on the north at the head of the lake. The elevations within the
u-shaped valley of the lake ranges from lake level to more than 8,000 feet above sea level (Darvill, 1996).
4.1.1.2 Railroad Creek Watershed
Referring to Figures 4.1-1 and 4.1-2, the Railroad Creek watershed is situated approximately three quarters
of the way up the west side of Lake Chelan. The watershed is generally oriented in an east-west direction, I
and is approximately 20 miles in length. The Railroad Creek drainage was also glacially carved and is'
generally u-shaped, with steep side slopes. The portion of the drainage near ~ ake Chelan is gently sloping .
at the mouth for approximately one-half mile, becoming relatively steep, with several waterfalls for the first
few miles. The drainage then transitions to a more moderate gradient past the Site. The western portion of
the drainage again steepens before reaching Lyman Lake and Lyman Glacier.
Topographic coverage of the Site and vicinity is indicated in the United States Geological Survey, 7.5
minute Quadrangle for Holden, Washington, dated 1944 &d corrected in 1968. The elevations within the
watershed range from the level of Lake Chelan to more than 9,500 feet above sea level (Bonanza Peak)
several miles west and north of Holden Village. Elevations of Railroad Creek range from 1,100 feet above
sea level at Lucerne, which is located on Lake Chelan, to 6,500 feet above sea level at the headwaters near
Lyman Glacier. The Site is situated approximately mid-way up the Railroad Creek drainage.
4.1.1.3 Holden Mine Site
The Site is located in Section 7, Township 31 North, Range 17 East in Chelan County. Referring to
Figure 4.1-3, most of the abandoned mine facilities and tailings are between the 3,200 and 3,400 feet above
sea level which is up to approximately 200 feet above Railroad Creek and Holden Village. The original
mine workings are situated above the main Site vicinity in the area noted as Honeymoon Heights, which
ranges in elevation up to approximately 4,600 feet above sea level.
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17693-005-019Uuly 19. 1999;4:51 PM;DRAFT FINAL RI REPORT