Watershed Management Plan - Mason County

Appendix
A Sub-basin Summaries
Four applications for groundwater are pending in the Duckabush sub-basin;
no applications for surface water are pending (Golder Associates, 2003).
WATER QUALITY
The Department of Ecology considers the Duckabush River to be impaired
based on water temperature exceedances measured in 2002 at river mile 4.5.
HABITAT
The Duckabush sub-basin provides habitat for chinook, coho, chum, and
pink salmon, as well as steelhead and cutthroat trout. Steep river walls,
impassable falls, and cascades limit anadromous fish populations to the
lower 7.5 miles of the Duckabush River (May and Peterson, 2003).
The lower reaches of the Duckabush are in relatively good condition,
although much like the Dosewallips, development in the Duckabush has
limited habitat by decreasing channel complexity and contributing to
degradation of the estuary and riparian areas.
In general, habitat above (west) of the estuary is in good condition due to
the management practices of the Olympic National Park and Olympic
National Forest (May and Peterson, 2003). The main factor that has limited
habitat quality in the middle and upper reaches is excess sediment
delivery to stream channels in the sub-basin is caused by mass wasting
events resulting from road construction, logging and clearcuts, and fire
(natural and human-caused) (May and Peterson, 2003). Above-normal
levels of suspended and deposited sediment can be harmful to fish health
and can negatively impact water and habitat quality. Few artificial barriers
exist – most are natural cascades or waterfalls.
KEY ISSUES IN THE DUCKABUSH SUB-BASIN
Based on the existing technical information in the Duckabush sub-basin,
the following key issues emerge:
• Limited available water temperature and pH measurements have led
the Department of Ecology to consider the Duckabush River a
“water body of concern.” More temperature and pH data are needed
to discern whether or not a problem exists.
• Roads and residential development have degraded and limited fish
access to habitat in the estuary and in riparian areas;
• The construction of dikes, channeling of the stream, and removal of
large woody debris have led to decreased habitat quality;
• Streams suffer from excess sediment loads due to a variety of factors,
including road building, poor forest management practices, and fire;
and
• Population growth and future development may place further strain
on water resources in the sub-basin.
page 70 Final Plan for County Adoption – May 11, 2006