Watershed Management Plan - Mason County

Sub-basin Summaries
Appendix
A
Creek and Mulberg Creek, but not in Alderbrook Creek, the “Unnamed
Creek”, Twanoh Falls Creek, Happy Hollow Creek, Holyoke Creek,
Deveraux Creek, or Shady Beach drainage. Measurements in Twanoh
Creek were “borderline” (Envirovision, 2005). Given the discrepancy
between this more recent data and past measurements, further study is
needed to determine to what extent water quality (particularly fecal
coliform) is a concern in the South Shore sub-basin.
According to the 303(d) list, the Great Bend and Lynch Cove marine waters
are also impaired due to pH fluctuations and low dissolved oxygen.
Saltwater intrusion may impact water quality in the sub-basin’s wells.
HABITAT
The South Shore sub-basin provides habitat for several fish species
including chum and coho (Golder Associates, 2003), as well as cutthroat
trout and steelhead (Skokomish Tribe, personal communication, December
23, 2004).
Fish habitat in the sub-basin is limited by residential development along the
shore of Hood Canal and State Route 106. In addition, culverts and other
barriers are a particular concern in Devereaux Creek, Springbrook Creek,
Twanoh Falls Creek, and Dalby Creek (WCC, 2003a).
INSTREAM FLOW
Unlike any sub-basin in WRIA 16, the South Shore sub-basin (technically
part of WRIA 14) contains two streams that are closed to further
appropriation during certain parts of the year. In 1984, WAC 173-514
closed many streams in WRIA 14 to further consumption, including
Alderbrook Creek and Twanoh Creek. Minimum instream flows, however,
were not set in these creeks.
KEY ISSUES
Based on the existing technical information in the South Shore sub-basin,
the following key issues emerge:
• Water quantity may be a concern in the South Shore sub-basin in the
near future; wells in the sub-basin may be at risk for saltwater
intrusion, water allocation is higher (as a percentage of supply) than
in any other WRIA 16 sub-basin, several applications for
groundwater rights are in outstanding, and the sub-basin is subject to
high development pressure;
• Fecal coliform measurements exceed state standards in several creeks
and in Great Bend and Lynch Cove, and have led to commercial and
recreational shellfish harvesting closures;
Final Plan for County Adoption – May 11, 2006 page 89