13.01.2013 Views

Dames & Moore, 1999 - USDA Forest Service

Dames & Moore, 1999 - USDA Forest Service

Dames & Moore, 1999 - USDA Forest Service

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

This reach is similar to Reach D adjacent to and immediately downstream from the mine because it is<br />

contiguous, drains to the same watershed, has a similar channel slope and is believed to have the same<br />

riparian and valley conditions as the reach near the Holden Mine.<br />

The reaches of Railroad Creek downstream from approximately Seven Mile Creek to Lake Chelan (Reaches<br />

C, B, and A) exhibit different characteristics compared to the reference reach at RC-1 and RC-6. In general<br />

the channel slope is steeper, the contributing watershed area is larger and the valley width is narrower than<br />

at the Site. The reference reaches for Railroad Creek downstream from Seven Mile Creek (reaches C, B,<br />

and A) were selected for conditions that may be generally comparable to natural conditions of the lower<br />

reaches of Railroad Creek (i.e., in the absence of the Holden Mine).<br />

The candidate reference reaches (including RC-6 and RC- 1) were compared to each of the Railroad Creek<br />

reaches (A through E) to identify the most representative reference reach for each Railroad Creek reach<br />

based solely on information obtained from topographic and geologic maps. Ten hydro- and geo-<br />

morphological parameters were considered pertinent to the identification of representative reference<br />

reaches. The ten parameters have varying influence on the quality of potential aquatic resources at each .<br />

reference site. Furthermore, other factors such as fishing pressure, and presence or absence of quality<br />

trout habitat also have influence on the quality and quantity of aquatic resources. The parameters<br />

considered during the selection of reference reaches are as follows:<br />

Channel slope<br />

Valley width<br />

Watershed area size<br />

Presence of glaciers within the watershed<br />

Lakes within the watershed<br />

Dominant geology<br />

Elevation<br />

Drainage network (stream order)<br />

Aspect<br />

Presence of downstream fish barriers<br />

Evaluation of these parameters resulted in the selection of those reference reaches that had seven or more<br />

parameters which matched within a particular Railroad Creek reach. Final selection of reference reaches<br />

was determined through field verification during early September 1997, and with USFS concurrence.<br />

As a result of the above process, the following reference locations and their comparable Railroad Creek<br />

reaches were selected:<br />

Reference Location comparable Railroad Creek Reach<br />

Railroad Creek (RC-6) D and E (RC-9 and RC-7)<br />

Railroad Creek (RC- 1) D and E (RC-9 and RC-7)<br />

Bridge Creek (near dmile camp) D (RC-5a and RC- 10)<br />

South Fork Agnes Creek (downstream from Swamp Creek) D (RC-Sa and RC- 10)<br />

The evaluation of potential reference sites failed to identify segments suitable fir comparing to Railroad<br />

Creek reaches "C" "B" and "A." Reaches "C" and "B" are relatively steep in gradient as the creek flows<br />

down through a deep canyon before entering reach "A." Various points within reaches "B" and "A" were<br />

G:\WPDATA\OOSREPORTSWOLDM-2W-O.DOC 4-95 DAMES & MOORE<br />

17693405419Uuly 19. <strong>1999</strong>;4:31 PM;DRAFT FINAL RI REPORT

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!