'Big burst' plagued a Seattle dam decades ago

Seattle has had its own trouble with a dam that seeps water.

In 1915, as the city filled its new Masonry Dam on the Cedar River, water leaked through the rock, gravel and sand on its north side into nearby Rattlesnake Lake more than a mile away.

Water slowly rose until it flooded Moncton, also known as Cedar Falls, a company town for Milwaukee Railroad workers south of North Bend. The railroad relocated the town to higher ground.

A more violent episode occurred during a storm two days before Christmas in 1918. Water held behind the dam seeped through a ridge and saturated a hillside in a watershed nearly a mile away until, late at night, it gave way.

The torrent rushed down Snoqualmie River tributary Boxley Creek toward the mill town of Edgewick. When night watchman Charles Moore saw the creek rising, he sounded the mill whistle and banged on residents' doors.

Townspeople heard a huge roar as a mill dam lower on the creek collapsed. They ran for their lives before the shingle mill was swept away and homes were toppled.

Since the "Boxley Burst," Seattle never has filled the reservoir to capacity.

Two years ago, Seattle installed drains at West Boxley Springs to remove groundwater, which otherwise could cause another dangerous landslide in an earthquake.

"We are confident we will not have a big burst as we had before," Seattle Public Utilities dam-safety supervisor Daniel Huang said.

This report is based in part on reports from The Seattle Times, Seattle Post-Intelligencer

and History Link.