Government officials regulating the reservoirs of the Colorado River are facing an unusual problem: how to keep the swelling desert river from creating the worst flooding in the Southwest since the first dam was built on the Colorado in 1935.
Late winter storms, followed by an early heat spell, have sent the snow pack from the western slope of the Rockies into the swelling tributaries of the Colorado River. Downstream, Lake Powell, the reservoir of Glen Canyon Dam on the Arizona-Utah border, is approaching capacity.
Consequently, US Bureau of Reclamation officials must ''spill'' water from the dam toward the Grand Canyon and into the lower Colorado's three reservoirs downstream. The bureau is releasing 61,000 cubic feet per second (CFS) - more than 27 million gallons a minute - through the dam. Of that, 28,000 CFS is used by the eight generators in the dam's power plant. The rest is ''wasted'' water, shooting out in jet streams from steel valves or through concrete spillways that carry the excess water around the 700-foot-high dam.
Despite the record flows coming from Lake Powell, the 76,000 CFS coming into the lake is making the water level on the dam creep higher. Bureau officials may increase the dam's releases to 70,000 CFS.
''I don't perceive that the fact we're spilling water is something for me to get all that alarmed about,'' said Tom Gamble, Glen Canyon power plant operations manager. ''You give us the flows and we'll manage them.''
Downstream, where commercial and private river tours make the 280-mile trip through the Grand Canyon, the high water is making its mark. Commercial boatmen are floating over campsites where they once slept, and dodging trees instead of rocks.
''The major hazard with the high flows is (that) boats may be unable to reach people thrown into the cold water,'' said National Park Service river ranger Kim Crumbo. On Saturday, a 37-foot, five-ton motorized raft owned by Western River Expeditions was flipped in Crystal Rapid, injuring six passengers, spilling out equipment, and requiring helicopter evacuation of the crew and passengers.
So far, a handful of trips, mostly private, have been canceled because of the high, swift water. But the National Park Service's Grand Canyon River Unit is leaving such decisions up to the private trips and commercial tours after warning them of the added risks.
Farther south, below the reservoirs of the lower Colorado, increased releases from the Parker Dam are flooding homes, docks, and businesses in the Parker Strip directly below the dam. Arizona Gov. Bruce Babbitt declared a state of emergency in a three-county area along the lower Colorado.
Earlier this week, officials from Needles, Calif.; Mohave County, Ariz.; and the Fort Yuma Indian Tribe won a temporary restraining order limiting the Bureau of Reclamations discharges from the Hoover Dam to 31,000 CFS. The order was dissolved the next day, and releases from Hoover returned to 39,000 CFS. But a hearing is scheduled for Friday at a US district court in Los Angeles to determine how much the bureau will be allowed to release.
''This is controlled,'' Alden Briggs, engineer at the Bureau of Reclamation's Hoover Dam, said of the flooding. ''We're controlling the magnitude of the flood.''
Flood control is the bureau's top priority. Officially, state and federal reclamation officials say the late snows and hot weather are to blame for the current flooding. There were already surplus water supplies before the snows, and some excess water had been released earlier this year.
But privately, several officials acknowledged pressure from the states to keep the Colorado's reservoirs full, and thus not allow a margin of safety to accommodate the current high flows.
''The bureau is walking a tenuous line,'' said an official from California's Colorado River Board. ''They were under intense pressure from the states to keep as much water as possible in Lake Powell to protect against future droughts. The bureau said by reducing the water level in Lake Powell, it'll be prepared for floods such as this. The answer Upper Basin states have given the bureau: That is the problem of those encroached on the flood plain (downstream in the Lower Basin).''
''They want to keep the lake (Powell) high,'' an official in the bureau's Upper Colorado Basin office in Salt Lake City said of the Upper Basin states. ''The fuller the lake is, the better off they are.''
The reason the Upper Basin states want to keep Lake Powell full, say these officials, is their requirement to deliver, because of the 1922 Colorado River Compact and a subsequent treaty with Mexico, 8.3 million acre-feet per year to the Lower Basin states (Arizona, California, and Nevada) and Mexico.
''You've got to have some storage there to meet the commitment to the Lower Basin,'' said the bureau's Salt Lake City official. Therefore, he added, ''we're not in the storing mode. We're full.''
''The Bureau of Reclamation should have drawn down the lake,'' says Rob Elliott, owner of Arizona Raft Adventures, a boat company that runs regular trips through the Grand Canyon. ''No matter how fluky the weather patterns were in April, May, and June, they should have had a room for error - had a contingency margin of capacity left in that lake to accept a hundred-year flood if they had to.''
Although the runoff coming into the lake is down more than 50,000 CFS from its peak of three weeks ago, power plant manager Gamble said the flows will not be back to normal until late July.