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I I I I I I I I I I 1\ I I I I I I I I OD25~5 Slough, a 30 acre backwater in the latter stages of succession, was dredged by Reclamation in 1979 and 1980 as a part of a cooperative study project aimed at fish and wildlife benefits. Topock Gorge Division The Topock Gorge Division extends from the upper end of Topock Gorge to the upper end of Lake Havasu. Minimal maintenance work has been conducted in this Division in the past, due to the natural channel configuration and substrate, which consists of a deep channel bounded by high canyon walls. These are broken to form various small backwater wetlands. This division is entirely within the Havasu National Wildlife Refuge. Havasu Division The Havasu Division includes all of Lake Havasu and the river between Parker and Headgate Rock Dams. The effects of the high flows on the,river are marked in this division by sediment deposition in the upper end of Lake Havasu. The high flows of 1983 and 1984 deposited 10 million cubic yards of river sediment and extended the existing delta. The water level in Lake Havasu fluctuates between 440 to 450 feet msl in accordance with the Parker Dam operating criteria, although for practical purposes, the lake elevation has been maintained above 445 feet msl for the last 15 years. During a flood, a potential surcharge to elevation 455 feet msl may develop. In the Parker Dam to Headgate Rock Dam reach, an area commonly known as the Parker Strip, water levels are determined by discharge from Parker Dam and the backwater effect from Headgate Rock Dam. General channel stabilization activities are minimal due to the channel and bankline substrate. Most stabilization activities in this reach are conducted by entities other than Reclamation to protect local facilities. This division is the most intensely developed area for recreation along the river. The Parker Strip has been heavily developed for recreation purposes, and in recent years thousands of people have visited Lake Havasu to boat and water ski. Flood releases of 40,000 cfs from Parker Dam in 1983 caused damage to homes and businesses with river frontage in the Parker Strip. Parker Division The Parker Division is located between Headgate Rock and Palo Verde diversion dams, and encompasses most of the lands of the Colorado River Indian Tribes' Reservation. It is divided into two sections, Parker I & II, for better administration of the division. Parker I begins at Headgate Rock Dam and ends 2 miles south of Agnes-Wilson Bridge. Parker II starts at River Mile (R.M.) 163.3 and extends to R.M. 133.8, at Palo Verde Diversion Dam. The channel improvement work in Parker I was completed by 1967. The major aspects of Appendix C - 6