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Landmark day • Thursday, June 22, 1972

June 22, 1972: The Flood That Sold the Greenbelt

Nearly four inches of rain in eighty minutes, seventeen houses gone, and a city finally convinced that the wash needed to be a park.

Illustrated plaque for June 22, 1972 in Scottsdale history SALOON TRADING POST MOTEL JUNE 22 1972 BOOMTOWN

What happened

On the evening of June 22, 1972, a stalled thunderstorm dropped 3.85 inches of rain over the north half of the Phoenix metro in about eighty minutes. Indian Bend Wash, the twelve-mile drainage that runs through the middle of Scottsdale, ran bank to bank through neighborhoods that had been built across it; seventeen homes were destroyed and hundreds in Phoenix and Scottsdale were flooded. Engineers called it a seventy-year flood.

Why it matters

The 1972 flood ended the argument. The Army Corps of Engineers had proposed a concrete channel 170 feet wide and 23 feet deep in 1961; citizens had countered with a turfed floodway of parks and golf courses; the Labor Day flood of 1970 had made the danger real. After June 22 the council put a $10 million general-obligation bond for the greenbelt on the April 1973 ballot and voters passed it seven to one. The Indian Bend Wash Greenbelt, finished in 1985, became the national model for green flood control.

The argument before the storm

For a decade Scottsdale had been arguing about a ditch. Indian Bend Wash runs twelve miles through the middle of the city, dry eleven months of the year and a river the twelfth, and the subdivisions of the 1950s and 1960s had been built straight across it. The Army Corps of Engineers’ answer, in 1961, was a concrete channel 170 feet wide and 23 feet deep — the Los Angeles River treatment. The council endorsed it in 1962. Then Bill Walton, the Progress publisher, wrote a 1964 editorial proposing a turfed floodway instead — parks, lakes and golf courses that would carry the water and be worth something the other 364 days — and the city’s STEP committees took the idea up. Voters rejected the county’s channel bond three to one in March 1966, and Eldorado Park, the first piece of a green wash, was built in 1966–68. The Corps, after the Labor Day flood of 1970, agreed in 1971 to accept a greenbelt if the city would build it. Nobody had voted the money.

Eighty minutes

On the evening of June 22, 1972 a thunderstorm stalled over the north half of the Valley and dropped 3.85 inches of rain in about eighty minutes. Indian Bend Wash did what it had done for ten thousand years and what the maps had forgotten: it ran bank to bank, through backyards and living rooms and the cross streets that had no bridges, from the McCormick Ranch land south to the Salt. Seventeen homes were destroyed in Scottsdale and hundreds were flooded across the two cities. The National Weather Service still lists it among the Valley’s historic storms; the engineers rated it a seventy-year flood, twenty-one months after the last one.

Seven to one

The flood turned a planning debate into a mandate. The council put a $10 million general-obligation bond for the greenbelt on the ballot in April 1973, and voters approved it seven to one. The Corps issued its design memorandum the next spring; Chaparral Lake filled in July 1973; Vista del Camino and Chaparral Parks were built in 1974, Indian School Park in 1980; and in 1985 the eleven-mile Indian Bend Wash Greenbelt was declared complete — grass, lakes, golf and bike paths where the concrete would have been. It has carried every flood since, and it is the thing other cities send delegations to see. The Greenbelt guide covers the parks; the 1970s chapter covers the decade the gamble defined.