New Waddell Dam - Design and Operation

Design and Operation

The New Waddell Dam is 300 ft (91 m) high from the riverbed and 440 ft (134 m) high from its bedrock foundation. It is a zoned earth-fill type and is 4,700 ft (1,433 m) long; containing 16,200,000 cu yd (12,385,789 m3) of material. The dam has a crest width of 35 ft (11 m) and a base width of 1,514 ft (461 m). The reservoir created by the dam, Lake Pleasant, has a capacity of 1,108,600 acre·ft (1.367437965×109 m3) at its maximum elevation above sea level: 1,725 ft (526 m). At maximum elevation, its surface area is 12,040 acres (4,870 ha). The maximum conservation storage level of the reservoir is 1,702 ft (519 m) when the reservoir has a surface area of 9,970 acres (4,030 ha). Conservation storage for the reservoir is 812,100 acre·ft (1.001710600×109 m3) and minimum storage 40,500 acre·ft (49,956,014 m3). The dam sits at the head of a 1,459 sq mi (3,779 km2) catchment area. Located 1.25 mi (2 km) northwest of the dam and serving excess water levels are two different spillways; a 590 ft (180 m) long un-gated free flow with a crest elevation of 1,706.5 ft (520 m) and a 370 ft (113 m) long fuse plug embankment with an elevation of 1,711 ft (522 m). The free flow spillway has a discharge capacity of 187,000 cu ft/s (5,295 m3/s) and the fuse plug 129,000 cu ft/s (3,653 m3/s). At at elevation of 1,728 ft (527 m), both spillways would have a combined capacity of 316,000 cu ft/s (8,948 m3/s).

Water from the dam's reservoir is released through its outlet works or power plant to either the Waddell Canal or into Hank Raymond Lake which is formed just downstream of the dam by the Camp Dryer Diversion Dam. The diversion dam is a composite concrete and masonry dam with a height of 79 ft (24 m) and length of 872 ft (266 m). It can store up to 590 acre·ft (727,754 m3) at an elevation of 1,445 ft (440 m). Water from Hank Raymond lake is diverted into the Beardsely Canal which has a main extension 33 mi (53 km) long to serve 60 sq mi (155 km2) of the Maricopa Water District (MWD). The Beardesly Canal also has an interconnection 4.5 mi (7 km) south of the dam at 33°46′48″N 112°16′54″W / 33.78°N 112.28167°W / 33.78; -112.28167 (Beardesly Canal and CAP interconnection) with the CAP aqueduct which allows it to receive additional water from that source. Water released into the 4.7 mi (8 km) long Waddell Canal first travels under the Agua Fria River via a 2,440 ft (744 m) long siphon before being returned to the surface canal where it continues south to meet the CAP aqueduct just west of Arizona State Route 303. The capacity of the pump-generating plant, Waddall Canal and siphon is 3,000 cu ft/s (85 m3/s) while the outlet works for the diversion dam and Beardsely Canal are 5,600 cu ft/s (159 m3/s) but only 4,300 cu ft/s (122 m3/s) can be diverted to the canals at a time. Water from the New Waddell Dam reservoir augments supply in the CAP and helps deliver 15% more CAP water to Arizona. Water in Lake Pleasant is divided between the CAP (658,300 acre·ft (812,001,094 m3)) and MWD (162,142 acre·ft (199,999,212 m3)). Water from the CAP aqueduct is also drawn into Lake Pleasant via the New Waddell Dam's pump-generating station. During the winter months, when energy rates are low, additional water in the aqueduct is pumped a maximum of 192 ft (59 m) up into the lake for storage. During the summer months, when energy rates are higher, water is released back down through the generators for hydroelectric power production. Sale of this electricity is being used to pay part of the dam's cost. The pump-generating plant contains eight pump-generators and has an installed capacity of 45 MW.