Only small tributaries of the Gualala River have water cold enough to be optimal for salmonids and particularly coho salmon. As shown in Figure 2, minor tributaries of Rockpile Creek and the Wheatfield Fork alone have are optimal. Little Creek water temperatures may be cool and provide important salmonid refugia, but no temperature data are supplied. THP 1-04-030SON/TCP #530 must deal with the question of the importance of Little Creek to ecosystem function of Buckeye Creek and its ability to support salmonids and more genuinely with the potential impacts to water temperature of the project. The plan acknowledges that water temperatures may be increased if base flows decrease, but then fails to deal with potential effects of the project on base flows and temperatures (see below).
Sediment
Documents associated with THP 1-04-030SON/TCP #530 portray Buckeye Creek and its tributaries as being in advanced recovery from past timber harvest with regard to sediment impacts, but there is substantial information available to refute that assertion. The Gualala River watershed is listed as impaired for sediment under section 303(d) of the Federal Clean Water Act, which precipitated the Technical Support Document for the Gualala River Watershed Water Quality Attainment Action Plan for Sediment (CWQCB, 2001). This study found that human caused sediment delivery rates are approximately 200% above the natural background rates in the Buckeye Creek basin (Figure 3). Two tributaries of Buckeye Creek upstream of Little Creek, Franchini and Grasshopper creeks have recognized problems with sediment.
North Coast Regional Water Quality Control Board staff observed a significant amount of sediment in transport in Franchini Creek (Figure 4). The small particle size distribution and concave nature of the stream indicate very recent contributions of sediment (Dietrich et al., 1989), not advanced recovery.
Figure 3. The Buckeye Creek basin sources of sediment estimated
by the CWRCB (2001). Road sources had the highest sediment yield
in combination. Estimated sediment yield is shown as tons of sediment yielded
per square mile per year. From CWRCB (2001).
Figure 4. Franchini Creek and NCRWQCB staff during 2001 survey indicating
major sediment problems and recent active contributions.