Recommendations

What watershed and habitat improvement activities would most likely lead toward more desirable conditions in a timely, cost effective manner?

Consider migration barrier removal in Palmer Canyon and McKenzie creeks;

Consider careful planning of land uses that could exacerbate mass wasting, since the relative potential of landsliding is high to very high in 50 percent of the subbasin;

Decommission and revegetate streamside roads, focusing on those where channel braiding and/or aggradation are persistent today, such as the central and upper reaches of McKenzie Creek, and the lower reaches of Marshall, Palmer Canyon, and Wild Hog creeks;

Continue to incorporate mitigation elements into Timber Harvest Plans for decommissioning legacy streamside roads and upgrading road drainage facilities in the lower subbasin, including Little and Big Pepperwood creeks;

At stream bank erosion sites, encourage cooperative efforts to reduce sediment yield to streams;

Reduce livestock and feral pig access and subsequent impacts to the riparian zone to encourage stabilization of stream banks and re-vegetation. This problem is most common on Marshall Creek;

Improvement of riparian canopy is the third priority restoration recommendation. Ensure that adequate streamside protection zones are used to reduce solar radiation and moderate air temperatures;

Retain, plant, and protect trees to achieve denser riparian canopy cover where current canopy is inadequate, particularly in the Upper South Fork and its tributaries, McKenzie, Wild Hog, and Palmer Canyon creeks;

Encourage the addition of large organic debris and shelter structures in order to improve sediment metering, channel structure, channel function, habitat complexity, and habitat diversity for salmonids;

Conduct both instream and hillslope monitoring to determine whether current land use practices are allowing for recovery and protection of the salmonid habitat in the subbasin. Improve baseline information on habitat conditions by conducting inventory surveys in the South Fork and major tributaries upstream of the confluence with the Wheatfield Fork;

Encourage more habitat inventory surveys and biological surveys of tributaries as only 31 percent of the subbasin has been completed;

Expand continuous temperature monitoring efforts into the upper subbasin and tributaries. Consider canopy composition, air and water temperature monitoring to examine canopy, temperature, and other microclimate effects on water temperatures.

Conclusions

The Mainstem-South Fork Subbasin is characterized by a confined narrow valley thought to have been formed by the San Andreas Fault. This valley contains the twelve-mile long flood plain of the South Fork Gualala River. The entire subbasin is near the coast and influenced by summer fog. About half of the subbasin has high to very high potential for landsliding, and landslides represent a major source for stream sediment. The limited data available also show that historically logged areas have contributed sediment to the streams.

Historic and current accounts show that coho salmon and steelhead trout inhabit the subbasin. Although relatively high instream sediment levels, simplified salmonid habitat, and a lack of appropriately sized spawning substrate are observed in the subbasin, available data and air photos indicate that present conditions are suitable for salmonids and instream and near stream conditions have improved since 1984.

The salmonid populations are thought to be currently constrained by a lack of instream complexity, such as that formed by in-channel large woody debris. Elevated water temperatures found along the South Fork mainstem are exacerbated by low canopy cover in some locations. Elevated levels of sediment yield are thought to contribute to some negative stream impacts. The unstable and erosive terrain should be considered during project planning and design. Caution and appropriate best management practices should be followed during implementation to minimize erosion and sediment delivery to streams.

Current landowners and managers interested and motivated to improve watershed conditions and re-establish suitable conditions for salmonids are encouraged to do so through improved land use practices. They are encouraged to enlist the aid and support of Gualala Basin restoration groups and agency technology, experience, and funding opportunities.