Wetland and Stream Study - Auburn, WA
This wetland and stream study conducted in Auburn, WA included several parcels which
have been impacted by diverted storm water.  Because the County's Municipal Separate
Storm Water System (MS4) had not been developed in the area where storm water was
being diverted, localized flooding was occurring.
The existing storm water
facilities in the area were old
agricultural drainage ditches
that had been classified as
streams sometime prior to
1990.  These ditches were not
designed for the increasing
flows of diverted storm water
and were not being
maintained as storm water
ditches due to the stream
classification that had been
The seasonal flooding impacted the forest vegetation, including Hemlock and Douglas fir
and encouraged the growth of red alder and other vegetation that would be considered to be
wetland vegetation.  However, the soils had not developed hydric soil characteristics and the
flooding in the area was technically a violation of the County's MS4 Phase II Municipal
Stormwater Permit.  SNR did not identify potential ratable wetland areas to be present on the
subject property due to the lack of naturally occurring wetland hydrology and the absence of
hydric soils.  King County and the City of Auburn are working on the MS4 system to eliminate
the localized flooding problems.