This polygon shapefile shows the riparian extent of the Russian River main stem, Alexander Valley Reach, Sonoma County, California in 2000. The Alexander Valley Reach extent is defined by the Jimtown Bridge and Cloverdale, Sonoma Co. Riparian habitat is defined as the river channel and all areas covered by riparian vegetation along the Russian River's "main stem", including the wetted channel, active channel, vegetated channel, channel banks, and that portion of the floodplain between the top of the channel bank and the outer limit of "typical" riparian vegetation. This habitat supports various seral stages of riparian vegetation, and it is assumed to be subject to relatively frequent flooding wherever there are no artificial flood control structures.The mainstem Russian River riparian habitat boundaries were interpreted from Sonoma County Water Agency (SCWA) Aggregate Resources Management (ARM) Plan aerial photos. Some areas of the SCWA aerial photos were missing and limited the extent of the riparian habitat. Aerials from the County of Sonoma Information Systems Department / GIS Group were used to complete the riparian extent.The intended use of this layer is to support watershed analysis and planning.