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Wolverton Gulch is the western-most monitoring
site of the 11 sites that were used during the Van Duzen Watershed
Project. This stream is a tributary of Barber Creek, which drains
into the Van Duzen River near its convergence with the Eel River.
The Wolverton Gulch monitoring site is located in a very rural
area, but is nearest the town of Hydesville. Above this site is
a catchment area with approximately 4.65 miles of stream network.
Elevations in Wolverton Gulch range from 75 feet at its mouth
to over 1,550 feet in the upper reaches, and the monitoring site
itself is approximately 184 feet in elevation. The watershed is
completely in private ownership with considerable holdings by
Humboldt Redwood Company (formerly PALCO) in the upper reaches.
Vegetation is predominantly Coastal Redwood Forest, with abundant
hardwoods such as Red Alder within the riparian zone. The catchment
area of a monitoring site is important when considering upslope
factors that affect water quality in the stream. This area represents
the true watershed that lies above the point where water from
the stream is sampled, and from which all rainfall and sediment
are channeled into the stream down to the point where water is
withdrawn for turbidity and suspended sediment analysis.
Stream discharge is directly proportional to the
size of the catchment area - the greater the area, the more water
is carried by the stream during storm events. Wolverton Gulch
(actually a creek) itself is relatively small compared to other
streams within the project area, and the stream drains an area
of approximately 4.73 square kilometers which is equivalent to
1.83 square miles. During the first year of sampling (HY07) volunteers
recorded a maximum discharge of 201 cubic feet per second (CFS)
and an average discharge of 18 CFS, a maximum turbidity of 2,385
Nephlometric Units (NTU) and an average turbidity of 171 NTU.
In HY08, there was a maximum discharge of 101 CFS and an average
discharge of 17 CFS, a maximum turbidity of 2,496 NTU and an average
turbidity of 196 NTU over the winter sampling season. Over the
two seasons combined (HY07-HY08), the maximum discharge was in
HY07 at 201 CFS with an average of 17 CFS, maximum turbidity occurred
in HY08 at 2,496 NTU with an average of 183 NTU. This translates
to an average of 1,286 tons of suspended sediment per square mile
per year.
Wolverton Gulch runs year round and is therefore
referred to as a perennial stream (as opposed to an ephemeral
stream, which runs dry in the summer). Maximum weekly average
temperature (MWAT) in the summer of 2007 was 15.1 C, and in 2008
it was 14.2 C. Overall, temperatures are moderate compared to
some of the other streams sampled within the lower basin project
area. Wolverton Gulch has a road density of about 7.3 miles of
roads per square mile of watershed. As with all of the catchment
areas within the lower basin, this density of road networks receives
a rating of extremely high. In the 17-year period from 1991 through
2007, the proportion of the area harvested for timber equaled
82.8%, with clear cutting accounting for 32.3% of the total watershed
area.
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