Splash dams’ legacy is one of scars and damage, but a Lower Columbia group is trying to change that

KELSO — A legacy of obsolete logging practices popularized more than a century ago remains etched in the way the Coweeman River moves.

Long before rail lines and logging roads existed, massive tree stands were transported on waterways — like the Coweeman — throughout Western Oregon and Washington.

Fir trunks threaded through dense forestland that blanketed rolling hills. A stream’s natural flow successfully pushed logs downstream, but creating and controlling a reservoir expedited the journey, leading to the popular emergence of wooden splash dams.

This practice, spanning from the 1880s through the 1950s, was a spectacular feat – and one that readily fed a market hungry for timber, according to 1977 Cowlitz Historical Quarterly entries.

But, during its prime, splash damming could be explosive and, according to the U.S. Forest Service, is considered one of the earliest management disturbances to the Pacific Northwest’s rivers.

Watershed groups say the dams’ legacy can still be observed along the Coweeman main stem and its tributaries today – an influence they’re attempting to reverse, returning the waterway to its natural state.

“Every tree that was growing along the banks was scarred. Every pebble of gravel got flushed out. It was just terrible,” said Brice Crayne, restoration program manager for the Lower Columbia Fish Enhancement Group.

Lasting impacts

Historical documents point to the Coweeman River system hosting as many as five splash dams. The river was a prime pathway for pioneer loggers to make a living. Great fir stands, ready to be cut and sent to a sawmill, grew near the stream and its tributaries.

The Coweeman’s first splash dam appeared in 1880 on the confluence of the main stem and Baird Creek, with others later appearing in Moreland Creek, Mulholland Creek, Sam Smith Creek and Hill Creek.

As water pooled, logs would float and accumulate until timber companies opened a spillway, releasing an explosive flood. Loggers would stand along the water with pike poles, orienting logs so they would be straight when exiting. Downriver, they would be directed into the mill pond and held for processing.

Locals recollected seeing oxen haul logs from where they were cut and down to the river, they wrote in the quarterly. Eventually horses replaced the oxen, then came steam-powered engines followed by small tractors. Soon, the dams became obsolete as railways and roads became prominent means of transporting timber.

Today, when standing by the river, habitat loss may not look substantial to an untrained eye, Crayne said.

An intact floodplain is teeming with life – bugs, beavers and at-risk fish species. But the Coweeman isn’t intact, he said. Splash damming flushed out entire aquatic systems.

Loggers would remove boulders and fallen trees in rivers by blowing them to bits with dynamite, creating a clear path for logs. In doing so, they ruptured native habitat and transformed how water flowed, Crayne said.

Many sites have been reduced to bedrock, allowing water to slide across the land effortlessly and speedily. Cold pools of water, fine sediments and woody debris needed for salmon refuge and spawning waned. As a result, their flashy fish bellies are seldom seen in the Coweeman’s currents.

The Lower Columbia Fish Enhancement Group began addressing this “oversimplified” habitat and altered stream channel movement in 2016, the first of their many subsequent projects.

Rebuilding a natural habitat involves introducing bedrock, boulders and logs to a river channel. This will eventually develop an alluvial layer – or a thick underwater sheet of silt, sand and gravel mixed with other organic deposits — which is necessary to support fish migration.

Incrementally, the Lower Columbia Fish Enhancement Group has expanded its restoration work along the Coweeman main stem to surrounding creeks. The project, called Baird Creek Liberation, is an amalgamation of small pilot projects, which enabled the group to learn more about the watershed and balloon their approach based on results, Crayne said.

Scientists have already seen an improvement in fish populations.

Preliminary data indicates that juvenile and adult salmon and steelhead appeared in slightly larger numbers last fall in the Coweeman River, according to Cramer Fish Sciences, a consultant company involved in Baird Creek Liberation.

A fuller report of how wildlife is responding to restoration will be available this winter.

The Coweeman River’s response to habitat work is already “encouraging at its early stage,” said Hans Berge, a program manager with Cramer. As the site matures, its natural processes will return and, with it, a mosaic of life – as small as invertebrates and as large as beavers. If the river’s current trend continues, it will fully recover, which may take a couple of decades, he said.

Regional impacts

Legacy impacts aren’t isolated to Southwest Washington.

Dam remnants, archive searches and personal anecdotes point to the structures’ history throughout the region. Researchers identified 232 splash dams in Western Oregon, where most research is centered, but they existed as far north as southeastern Alaska, according to the U.S. Forest Service.

Although splash damming had far reaches, impacted rivers and estuaries can recover through minimal intervention, like that of the Baird Creek Liberation.

Each season water flows through the channels, sediment will find a place to stop among imported wood debris and rocks. But, for the most part, the water is doing all the work, Berge said.

“If you fight nature, you won’t get results,” he said. “If you use the river as a tool to complement restoration work, it almost always plays out.”