The Siletz River flows through two divisions of the Coast Range topography, the flat coastal margin and the mountainous uplands.

The coastal margin consists of flat marine terraces at elevations of 15-60 m. These terraces average about 1.6 km in width and they are repeatedly broken by basaltic headlands extending seaward from the mountains.

The uplands are composed of moderate slopes (150-210 meters) near the terraces, but quickly become steep and rugged to the east.

Typical elevations near the crest of the Coast Range reach 455-610 m, and higher peaks up to 1015 m about (e.g. Fanno Ridge, Stott Mountain, Laurel Mountain, Euchere Mountain).

Ridges occur randomly, but tend to follow a slight northwest to southeast trend. Igneous rocks underlie the highest peaks in the range.

Just over 117 km (73 mi.) long, the Siletz River drops 884 m (2900 ft.) and drains a watershed of 955 km2 (373 mi2) during its journey to the Pacific Ocean (Wisely and Ham, Inc. 1974).

Starting as a trickle deep within the Coast Range in Polk County, the Siletz flows through two counties and the Siuslaw National Forest before emptying into the Pacific in a small tidal estuary.

Tidal flow from the ocean extends 22.5 river miles inland, to just below Jack Morgan State Park.

The Siletz Watershed Council meets the third Tuesday of each month at 7 pm (except for July and August) at the Siletz Library, 255 S. Gaither St. Siletz, Oregon. Check our calendar for monthly meeting information or subscribe to have monthly reminders emailed to you. Email Greg Harlow for more information at siletzwatershedcouncil@gmail.com.

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