The Mattole Landscape

The Mattole watershed landscape is continually reshaped and defined by both geological processes and human activity.  Located within the junction of three tectonic plates -- North American, Pacific, and Gorda plates -- the watershed experiences frequent seismic activity.  High rates of coastal uplift have left the river coursing through "soft" geological terrain prone to landslides and sedimentation.  Biologically, historical logging during the 1950s and 60s led to the establishment of second growth conifer forests.  The areas around the headwaters are populated with primarily mixed conifer forests and smaller pockets of hardwood forests.  Annual grasslands begin to emerge further downstream closer to the northern river basin.

Winters in the Mattole are characterized by cool and wet winters with high rates of runoff while summers are very dry and warm.  Temperatures in the watershed range from below freezing in the winter to above 100F during the summers.  Annual rainfall averages to 80 inches per year with the mainstem around Honeydew receiivng the most amount of rainfall.  The "Mediterranean" climate of the Mattole watershed cause substantial fluctuations in the rivers flow which can range from 12 cubic feet per second (cfs) to an astonishing 90,000 cfs during one of the greatest flooding events in the Mattole valley.  Both flashy flows and seismic activity have shaped the Mattole with steep slopes at higher elevations and flat alluvial basins lower in the valley.