BALANCING RESERVOIR IN THE GRAND COULEE

SIZE AND CAPACITY

By means of two earth dams about 100 feet high, one 2 miles from the Grand Coulee Dam and the other near Coulee City, a balancing reservoir 27 miles long and covering an area of about 27,000 acres, or 43 square miles, will be formed in the upper Grand Coulee, its high-water level being 280 feet above that of the storage reservoir behind the Grand Coulee Dam. The maximum capacity of the balancing reservoir will be approximately 1,150,000 acre-feet, of which about one-half million acre-feet will be useful in regulating pumping and water consumption.

Only a part of the irregular coulee floor will be flooded, but practically all of the railroad and much of the highway in the coulee will be inundated.

"Modified" cement of five brands, blended here, is pumped by compressed air through a 6,200-foot pipe line to the concrete mixing plant

CANALS AND DISTRIBUTING SYSTEM

Through a canal of 15,000 second-feet capacity, water will be carried about 10 miles southwesterly from the balancing reservoir to the heads of the 150-mile east-side canal and the 100-mile west-side canal, from which it will be distributed to farms through numerous laterals. Several large tunnels, siphons, wasteways, headgate structures, and bridges, and a drainage system for collecting and using seepage water will be required.

A record of 9,290 yards of concrete in a single day was established by this mixing plant

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