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- 4 - DESCRIPTION OF THE WATERSHED r Physical Data ~;' ~. , i Location and Size.- The Franktown-Parker Tributaries of Cherry Creek Watershed, hereinafter referred to as the Franktown-Parker Watershed, is located in east-central Colorado and includes parts of Douglas, El Paso, and Elbert Counties. The watershed is about 38 miles in length and averages about 10 miles in width. The total watershed area is 176,640 acres (276 square miles), of which 154,500 acres are in Douglas County, 15,140 acres in El Paso County, and 7,000 acres in Elbert County. t I I ~ Cherry Creek is an intermittent northward-flowing stream, which joins the South Platte River within the Denver city limits approxi- mately 15 miles downstream from the lower limits of the Frankto1m- Parker Vlatershed boundary. The West Cherry Creek Watershed Project*, which is now under construction, embraces one of the principal upper tributaries of Cherry Creek. Physiography.- The watershed lies several miles east of the Front Range of the Rocky Mountains and is within the Colorado Piedmont section of the Great Plains physiographic province. Elevations range from 5,700 feet above mean sea level at the lower end of the watershed to 7,700 feet at the headwaters on the drainage divide between the Arkansas and South Platte River basins. ~ . A narrow belt across the central part of the watershed is characterized by topography of sharp relief, resulting from the presence of a very resistant rock layer, the Castle Rock conglomerate. Steep canyon walls and mesa fronts 200 to 400 feet high are common in this belt. Cherry Creek and some of its tributaries have cut narrow canyons through this belt. The remainder of the watershed has moderately to steeply rolling topography. Occasional steep-sided buttes and mesas occur in the upper area. I ~ I t - The drainage pattern is dendritic with the mainstem of Cherry Creek lying almost along the mid-line of the watershed through the lower area. In the lower part of the watershed the area subject to flood overflow along Cherry Creek averages about 1,200 feet wide. Between a point two miles south of Franktown and a point about eight miles upstream, Cherry Creek flows through a narrow canyon cut in the Castle Rock conglomerate. The area subject to overflow in the canyon section is negligible. Upstream from this canyon the Cherry Creek drainage is divided between three major tributaries: East Cherry Creek, vlest Cherry Creek, and Antelope Creek. Another major tributary, Lake Gulch, enters Cherry Creek from the west midway in the canyon section. The width of the overflow areas along these major upper tributaries averages about 700 feet, * Hest Cherry Creek is excluded from the work plan, A separAte plan. dated July 1958, has been surn.itted for West Cherry Creek.