Wolverton Gulch Catchment Area

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is sampled, and from which all rainfall and sediment are channeled into the stream down to the point where water is withdrawn for turbidity and suspended sediment analysis.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.

Wolverton Gulch photo 1
Wolverton Gulch monitoring site after a moderate storm event. (Photo by K. Bromley)
Wolverton Gulch photo 2
A calm pool in Wolverton Gulch after a particularly large storm event. (Photo by K. Bromley)

Wolverton Gulch photo 3
Wolverton Gulch monitoring site during an especially heavy storm event. Note the staff plate in the lower left of the photo.
(Photo by K. Bromley)

Wolverton Gulch photo 4 Wolverton Gulch monitoring site on a peaceful day in late spring. (Photo by P. Trichilo)

Friends of the Van Duzen River
PO Box 315
Carlotta, CA 95528