Mark West Creek is a tributary to the Russian River, located in Sonoma County, California (see Mark West Creek map, page 2). The legal description at the confluence with laguna De Santa Rosa is T8N, R9W, S32. Its location is 38 29'30" N. latitude and 122 53'30" W. longitude. Mark West Creek and its tributaries drain a basin of approximately 40 square miles. Mark West Creek is a fourth order stream and has approximately 27 miles of blue line stream, according to the USGS Camp Meeker, Healdsburg, Sebastopol, and Mark West Springs 7.5 minute quadrangles. Major tributaries include Porter Creek and Humbug Creek both of which are described in separate stream reports. Elevations range from about 40 feet at the mouth of the creek to 1800 feet in the headwaters. The topography is mountainous in the headwaters, becoming a flat valley in the middle section and turning to low hills near the mouth. Most of the stream in the middle section is bordered by cultivated fields and housing developments. Vegetation near the mouth is typical Redwood Forest. The vegetation near the headwaters is characterized by oaks, bays, redwoods, Douglas-fir, maples, madrone, and manzanita.