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VII 1-3 There are three weirs of significant height and numerous small drops over concrete casing or steel piles driven to protect pipe crossings, Opposite Columbine Valley there is a gabion weir approximately 8 feet high at River Station 1967 + 00. Immediately downstream from West Union Drive, there is a concrete weir, approximately 11 feet high which diverts water to Englewood. The weir sits on the Denver Formation which is exposed immediately down- stream. The third weir protects the Denver Water Board's twin aqueducts where they cross under the South Platte River approximately 700 feet up- stream from the West Oxford Avenue bridge. This weir causes an 8-foot drop in the riverbed profile. The Corps of Engineers (1983) are in the process of channelizing the South Platte River from the south side of Columbine Valley to West Oxford Avenue to contain the river and to accommodate larger flows. The proposed project consists of enlarging the channel by lowering the bed and widening and straightening the existing channel. Sharp bends will be eliminated. The materials dredged from the channel will be used to raise the banklines. The width of the river bed varies greatly in this reach. The average is 160 feet. Where encroachments have been made by dumping fill on the low river- bank, the riverbed is only about 60 feet wide. The narrow section is from West Belleview Avenue to West Hampden Avenue, except through the Englewood Municipal Golf Course. Due to the high weirs and the encroachments and other works of man, the bank heights are also highly variable. Both banks will be blanketed with riprap. Three bed grade control struc- tures will be built to replace those weirs existing now. Other works are needed to protect old and relocated water, sewer and other utility lines crossing the river. Six inches of cobblestones will be added to the channel bottom and banks in selected areas to prevent excessive erosion. The local sponsor for the project is the Colorado Water Conservation Board. The South Platte River has been changing its alignment in this reach. Between West Union Drive and West Hampden Avenue, gravel miners have re- located the river various times in the last 25 years. Part of the Englewood Municipal Golf Course on the right side of the river was once a large gravel pit. A large pond formerly on the golf course site has been filled in. The fill material forms the right bank of the river and is highly erodible. This bank is more than 10 feet high. The river is wider than normal through the go If course. West Hampden Avenue to Sand Creek, This is the urban reach of the South Platte River. Over its length of 13.8 miles, the river falls 159 feet. One or both banks are stabilized with a variety of materials including rubble, riprap, concrete, concrete piles, and timber piles. Although there are local areas where the river is endeavoring to erode its banks, the urban reach of the South Platte River is essentially locked in place. When ero- sion occurs it is repaired before damage to expensive property happens. The river has been straightened so that its sinuosity is only 1.09. A sharp bend still remains immediately upstream from Sand Creek. At the Bowles Avenue bridge, bedrock is 37 feet below the riverbed. At Belleview, it is 9 feet below and immediately downstream from the weir at West Union Drive, the Denver Formation outcrops on the bed of the South Platte River. There are numerous drops in the riverbed level along the urban reach. Many are small one or two foot drops; others are substantial. Public Service Company of Colorado has a collapsible fabric dam at their Zuni Plant at Thirteenth Avenue in downtown Denver. The vertical drop across the dam is 8 feet. Of the total drop of 159 feet, approximately one-third (57 feet) occurs at the drop structures. Bear Creek enters the South Platte River approximately 1/4-mile upstream from West Hampden Avenue. A few hundred feet upstream from the mouth, Bear Creek flows over a rapids where the Denver Formation outcrops. Local sub-reaches which are very steep are from the Cherry Creek confluence to 23rd Street (20 feet per mile), and from 38th Street to the Burlington Northern Railroad Bridge (23 feet per mile). Here, bedrock is exposed which has been taken advantage of as a semi-whitewater area for boating. Overall the average slope between drops is only 8 feet per mile.