UNITED STATES DEPARTMENT OF THE INTERIOR BUREAU OF RECLAMATION REGION 3 A. B. West, Regional Director LOWER COLORADO RIVER MAPS COLORADO RIVER FRONT WORK AND LEVEE SYSTEM ARIZONA-CALIFORNIA-NEVADA October 1969 PLATE I Laguna Division Mohave Volley Division 1 Topock Havasu Division Parker Division Polo Verde Division Cibolo Division I Imperial Division Yuma I Limitrophe Gorge 1 Division Division Division I I ...---..... i 1 r MI 51515.4 IMPERIAL MI es kPALO VERDE DIVERSiON, DAM DAM,' LAW 657.2 DAM 444.0 10POCK O54D0 /1—L/ ----7 i,DAVIS • nbeill/. " : I l 42 / I ' 1.4ohave "Water MI. 619.9 _Taylor F.rry Cit Needles Wheel\ ) •Blythe Adobe Ruins o rtAv Pict:who Alma MI.460 MI so MI $942 / BM MEND ---., cl • MORELOs DA ( MI. 685.7 a./LF k;Afy,t. "Pot, PALO-- VE ce .erum DRAIN .0v.. our::: OF \ CALIF. / I \ '. MI 700 fra. of` Ine R. •••11111( UNITED STATES DEPARTMENT OF THE INTERIOR BUREAU OF RECLAMATION 10 0 1 0 20 REGION 3 SC ALE OF MILES OPERATIONAL DIVISIONS LOCATION MAP DRAWN _it - - - - - - - - - SUBMITTED - - - - - - - - - - - - - - - - - - - - TRACED - - - - - -RECOMMENDED ............... CHECKED AVM APPROVED ........................................... KEY MAP BOULDER CITY, NEV. SEPT. 5,1969 I 423-300-829 ABSTRACT This booklet of maps contains information on the Bureau of Reclamation's Colorado River Operation and Maintenance (O&M) Program. The program is being carried out under the authority of the Colorado River Front Work and Levee System Act of January 21, 1927, and subsequent amendments thereto. For administration purposes, the Colorado River below Davis Dam has been divided into ten operational Divisions as shown on the frontispiece map. The work which has been completed thus far, as well as future work which is in the advanced planning stage, is shown on the facility maps of the respective Divisions. To aid in reading these facility maps, a key to the symbols used is included. For information purposes, a brief introduction to the problems leading up to an active operation and maintenance program is provided. The goals to be achieved by the work are also set forth. This is followed by a more detailed discussion of the problems inherent to each Division, the steps which are being taken to successfully resolve them, and the benefits which accrue from project features. TABLE OF CONTENTS PAGE ABSTRACT COLORADO RIVER OPERATION AND MAINTENANCE (O&M) PROGRAM ....... 1 Introduction ........................................ 1 Mohave Valley Division ............................... 3 Topock Gorge Division ................................ 5 Havasu Division ...................................... 8 Parker Division ...................................... 9 Palo Verde Division .................................. 12 Cibola Division ...................................... 13 Imperial Division .................................... 14 Laguna Division ...................................... 17 Yuma Division ........................................ 18 Limitrophe Division .................................. 20 KEY TO SYMBOLS ........................................... 21 TABLE OF CONTENTS (CONTINUED) LIST OF DRAWINGS TITLE DRAWING NO. PLATE NO. Operational Divisions - Location Map 423-300-829 Plate 1 (Frontispiece) Mohave Valley Division - Facility Map 423-306-1185, 1186 Plate 2 Topock Gorge Division - Facility Map 423-306-1187 Plate 3 Havasu Division - 423-300-804, 805 Facility Map 806, 808 Plate 4 Parker Division - Facility Map 423-306-1188, 1189 Plate 5 Palo Verde Division - Facility Map 423-306-1190 Plate 6 Cibola Division - Facility Map 423-306-1191 Plate 7 Imperial Division - 423-306-1192, Facility Map 1193 Plate 8 Laguna Division - Facility Map 423-306-1194 Plate 9 Yuma Division - Facility Map 423-306-1195 Plate 10 Limitrophe Division - Facility Map 423-306-1196 Plate 11 COLORADO RIVER OPERATION AND MAINTENANCE (O&M) PROGRAM Introduction In its natural state, the Colorado River flowed unchecked from the snowcapped Rocky Mountains of Colorado to the Gulf of California in Mexico. In the early years of American history, it was considered a natural menace. It tore through desert lands, flooded agricultural fields, and inundated villages. The magnitude of the riverf lows alternated between ravaging floods in the spring to a mere trickle in late fall. Western water planners, particularly those in California, supported the Bureau of Reclamation in doing something to control and harness the energy of the river. Consequently, a series of dams were built; namely, Hoover, Imperial, Parker, and Davis. However, construction of these regulatory structures resulted in secondary problems which assumed great importance. While the flow of the river had been regulated, instability of the river channel itself had not. It was necessary for the river to undergo significant changes as it adjusted to its new environment. Each reservoir, acting as a sediment trap, cleared up the muddy water and released clear water which then picked up sediment that had been deposited by earlier floods. The silt thus picked up moved downstream and was deposited on the riverbed in the slow-moving water at the head of the next reservoir. Thus the reaches of river below the dams were scoured and deepened whereas other reaches such as in Topock Gorge and the reach of river above Imperial Dam were raised by extensive sediment deposits. The effects of the raised riverbed in Topock Gorge extended north to the City of Needles where a portion of the city became inundated. This emergency situation at Needles led to new legislation designed to deal with river problems along the entire lower river below Hoover Dam. Existing authority under the Colorado River Front Work and Levee System Act was expanded in 1946 to permit the Bureau of Reclamation to initiate an active Colorado River Operation and Maintenance (O&M) Program. The initial goal of the work was to prevent flooding and destruction of lands resulting from meander of the river and deposition of sediment in the river channel. It was soon apparent, however, that other objectives needed to be incorporated in project plans such as salvage of water, stabilizing and enhancing fish and wildlife habitat, and improving recreational opportunities. To meet these goals, comprehensive planning reports have been prepared using multiple-purpose planning concepts for attainment of maximum overall 2 project benefits. Such multiple-purpose planning sometimes limits the attainment of single-purpose objectives such as the accomplish- ment of the greatest possible water salvage or the greatest possible recreational value. In multiple-purpose planning, each single-purpose objective is given weighted consideration so that the overall public benefits may be maximized. For administration purposes, the lower Colorado River below Davis Dam has been divided into ten Divisions as shown on the frontispiece map. The status of the program in each Division of the Colorado River Front Work and Levee System is discussed below. Mohave Valley Division Scouring of the river channel below Hoover Dam by the clear water released from the reservoir, and subsequent deposition of the sediment thus eroded in the zone of backwater influence of Parker Dam, created a problem of severe aggradation in the lower Mohave Valley. Prior to 1946, aggradation of the channel in the lower valley caused a rise in average water levels until there was serious flooding near Needles and the threat of worsened conditions. Channel stabilization was initiated in 1949 with initial work consisting of dredging of an improved channel between Needles and Topock. 3 This work and associated levee construction eliminated the immediate threat to Needles. However, it did not, by itself, provide the river stability between Davis Dam and Topock which was needed to assure that the problem would not recur. Channel dredging, levee construction, and associated work were subsequently accomplished upstream from Needles to a point about 10 miles below Davis Dam to reduce the pickup and transport of sediment. A settling basin was also constructed in the river above Topock to trap the sediment arriving from upstream sources and prevent it from depositing in Topock Gorge. A 12-inch dredge has been used in the basin for removal of sediment deposition. As a result of this work, the needed stability of the channel was achieved and water levels at Needles were brought under control. Related work for the improvement of fish and wildlife habitat and recreational features has also been provided. Topock Marsh, which came into existence after the closure of Parker Dam and the filling of Lake Havasu in 1938, has been encompassed with a dike to maintain water levels at elevation 455 feet. At this water height, approximately 4,000 acres of open water are available for fisheries and wildlife manage- ment. Inlet and outlet structures were constructed to supply water apportioned to the Havasu National Wildlife Refuge. The Bureau of Reclamation participated in the development of Park Moabi Marina 4 below Needles. Popularity of the Marina has increased each year since its construction. Future work in this Division will pertain primarily to maintenance of constructed features. Other minor work which may be beneficial to channel stability or improvement of fish, wildlife, and recreation may be undertaken consistent with long-range plans. Aside from the benefits to fish and wildlife and recreation, the constructed features will reduce the sediment transport into Topock Gorge and Lake Havasu by about 121,000 tons per year. Water salvage