Mattole River - Ecology and Conservation

Ecology and Conservation

The Mattole River has been declared a 303(d) impaired waterbody that flows into a Marine Protected Area (Punta Gorda State Marine Reserve). Areas in the Mattole River watershed are undergoing restoration to restore habitat that was degraded by a combination of early industrial-style timber harvest techniques and associated road construction, naturally erosive geology, and two 100-year floods which occurred in 1955 and 1964. The Mattole River and Range Partnership, consisting of the Mattole Restoration Council, Mattole Salmon Group, and Sanctuary Forest, undertakes this work with the collaboration of watershed landowners and multiple private and agency funders.

The river is used for recreation and agricultural, municipal and industrial water supply. It also provides wildlife habitat including cold freshwater habitat for fish migration and spawning. The Mattole River is home to three salmonid species: Chinook salmon (Oncorhynchus tshawytscha), Coho salmon Oncorhynchus kisutch), and Steelhead trout (Oncorhynchus mykiss). All three are listed as threatened under the Federal Endangered Species Act. Coho salmon are additionally listed as threatened under the California State Endangered Species Act. The Mattole Salmon Group counted just three adult Coho salmon in the river this past 2009-2010 winter (and only one redd) which is the lowest number of coho counted since the group began surveys in 2004, and far below the historical estimates of thousands of 17,000-20,000 adults, or even 1950s and 1960s estimates of 8,000 and 5,000, respectively. Mattole Salmon Group Executive Director Keytra Meyer explained that even though the recent salmon surveys don't span the entire watershed, it is unlikely that the teams missed even 50 adult fish. Efforts to locate juvenile coho found them only in Thompson and Ancestor creeks, among the uppermost tributaries to the Mattole. In 2010-2011 ten coho were counted and five redds, but these numbers are still 95% lower than 2006-2007. Each salmon run is on a three year cycle.

The Mattole Restoration Council, the Mattole Salmon Group, Sanctuary Forest, the Mill Creek Watershed Conservancy, the Upper Mattole River and Forest Cooperative and the Mattole River and Range Partnership fosters the Mattole River habitat restoration work and serves as a model for other communitees who wish to work cooperatively to repair anadromous salmonid habitat. Recently the group is planning a pilot project to decrease winter runoff and increase summer flows using a beaver dam model. Ecosystem analyst Michael Pollock, from the Northwest Fisheries Science Center of NOAA Fisheries, is assisting with the project. His research has shown that salmon smolt production per beaver dam ranges from 527 to 1,174 fish, whereas production in a pool formed by large woody debris is only 6 to 15 fish. This suggests that re-establishment of beaver populations would be 80 times more effective in salmonid recovery efforts than large woody debris placement alone.

The common plant associations within the Mattole include the following: (1) Coast redwood forest (Sequoia sempervirens) (in the southern headwaters), (2) mixed Coast Douglas-fir (Pseudotsuga menziesii var. menziesii) and hardwood (primarily Tanoak (Lithocarpus densiflorus) and Pacific madrone (Arbutus menziesii) forest, (3) mixed chaparral (primarily manzanita Arctostaphylos spp., mountain whitethorn Ceanothus cordu-latus, scrub oak Quercus berberidifolia, and Coyote brush (Baccharis pilularis)), and (4) grasslands. Riparian zones of the Mattole, in addition to the above, also contain Bigleaf maple (Acer macrophyllum), Red alder (Alnus rubra), cottonwood (Populus fremontii), Oregon ash (Fraxinus latifolia), and Willow (Salix spp).