051218 historic flood.jpg

June of 1908 brought Missoula's biggest flood in recorded history. Two spans of the Higgins Avenue bridge that survived were moved upstream to make what's now the Van Buren Street footbridge.

Try as we might, Missoula and the Clark Fork River won’t make it through the spring any higher than No. 2 on the flood charts of history.

But let the record show we blew 1947 out of the water.

The U.S. Geological Survey’s gauge across the river at Canyon River golf course bumped up to a height of 13.75 feet between 12:30 p.m. and 12:45 p.m. Friday, equaling the second-highest flow of all (measured) time on June 21, 1975.

As the afternoon wore on, the river dropped slightly but was still expected to claim No. 2 for its own and keep rising toward 14.3 feet or more by Saturday night. And it could get even higher next weekend if snow that fell again Friday in the high country keeps filling the streams feeding the river.

It’s still a long way from the 17.4 feet of the famous flood of 1908, when houses, chicken coops, railroad grades and the middle of the Higgins Avenue bridge went sailing toward the Pacific.

A remnant of that flood is the Van Buren Street footbridge. The two surviving spans of the Higgins Avenue bridge were moved upstream to build a connection to and from the then-10-year-old University of Montana campus.

What sets the flood of 2018 apart is how early in May it’s happening. In a National Weather Service list of historic crests of the Clark Fork through Missoula, six of the top nine occurred in June, and none before May 18. The devastating flood of 1964 peaked in Missoula on June 10. 

The flood of '47 was a notable exception, though it ranks only 11th on the all-time chart. It peaked at 11.1 feet on May 9 and set daily maximum records for cubic feet per second each of the first 10 days of May that stood until 2018.

This year’s waters climbed from 20,000 cfs on Sunday to more than 32,000 on Friday, drowning the previous highs of 1947 each day, usually by 6,000 or more.

As is the case in 2018, the '47 flood followed a winter of record snowfall up high and a spate of hot May days. They were followed by heavy rains in the Missoula region on May 9 and 10.

The timber top of the dam at the Bonner lumber mill went out on May 5 (the day, by the way, Juliet Gregory assumed duties as Missoula’s first and so far only woman mayor). Manager W.C. Lubrecht announced operations would shut down at the mill until the water went down.

A mile or so downstream at the Milltown power dam, “cubic second feet” were measured at 20,500 on May 9. All four headgates were opened to release the pressing muddy water behind it, according to Montana Power Co. employees. When the first two 9-by-14-foot gates were opened and 6 feet of flashboards removed from the top of the dam, the river reportedly rose 14 inches.

The Bitterroot River lapped to the oil surface of Highway 93 at Buckhouse Bridge, and highway officials closed the road to all but local traffic.

Similar flood scenes were repeated with some frequency throughout the 20th century and beyond as railroad and interstate construction above town pushed the Clark Fork channels here and there.

But never so early in May. And rarely if ever for so long a period as forecasters predict in 2018.

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Mineral County, veterans issues

Outlying communities, transportation, history and general assignment reporter at the Missoulian