Renton has always had an uneasy relationship with the Cedar River, even after its wrath was controlled by the dam built by the City of Seattle above Landsburg.

But there was one Great Flood, when the Cedar, the Black and the Duwamish rivers joined forces to wreak havoc on Renton and up toward Kent.

It was a Sunday morning, nearly 100 years ago, on Nov. 11, 1911. Church bells tolled at about 8:30 a.m., nothing unusual for a Sunday.

But as Tom Monahan writes in his essay for the Renton Historical Society and Museum Quarterly, “A River Ran Through It: The Great Flood of 1911,” those bells weren’t a call to Sunday worship.

“Instead, the bells heralded a potentially lethal situation – announcing a day of terror for Rentonians living in the lower parts of the city,” wrote Monahan, who was a museum researcher.

The weather that day wasn’t anything unusual for a turbulent fall. Rain in the lowlands, heavy snow in the mountains and a warm wind, Monahan explains. All that water was headed down those three rivers, to the bottom of the basin – Renton. The dam on the Cedar hadn’t failed Renton yet.

But the city was gripped in fear.

Sentries were posted, with binoculars trained on the river. A system of signals was set up for the Denny-Renton brick plant siren. One was an all clear; the other would signal a dam failure – a constant 30-minute blast. The dam held, but false alarms had already created a panic and rightly so.

Water still rushed toward Renton, bringing with it logs and debris, which piled up against the bridges in the city. Even after 100 years, that scenario still plays out in Renton during major floods on the Cedar.

The raging water spread across Renton, forcing residents to flee to higher ground. Eventually, the waters receded and clean up began. Mud and debris filled basements and every street in town. No one died, Monahan reports, and the injuries were mostly minor.

But the Cedar River wasn’t finished with Renton.

As public works director, Gregg Zimmerman is responsible for much of the city’s flood control and response today. He, like almost everyone else alive today, wasn’t around for the 1911 flood. But he worked for the city in 1990, when the Cedar River struck a major blow to Renton.

Many of the apochrophal stories about flooding of the Cedar in Renton stem from that November storm. The National Weather Service ranks it as No. 10 in its top 10 list of the state’s major weather events in the 1900s.

That year, sandbags were stacked to prevent flooding of what was then the Renton City Hall next to Liberty Park. The Cedar nearly overtopped the sandbags. Prisoners in the city jail in the basement were evacuated because water was flowing up through the floor drains.

City officials feared the Houser Way bridge would give way from the force of logs and debris stacked up against it. The Renton airport and golf course suffered significant flooding. Boeing aircraft stored at the airport suffered some damage.

“After this flood event, we knew that steps needed to be taken to better protect the city from flooding of the Cedar River,” Zimmerman said.

Part of that effort was to work with Seattle Public Utilities to change the procedures for operating the Seattle-owned Masonry Dam on the Cedar to “more closely accommodate watershed conditions,” he said.

The Masonry Dam created the Chester Morse Reservoir, which supplies water to Seattle and the city’s water customers.

“These improved operating procedures at the Masonry Dam were one of the largest contributing factors to reduced flooding in Renton,” he said.

Renton has taken a number of others steps, too, (see the breakout box) that together have “dramatically decreased” flooding along the river in Renton, he said.

“Cedar River flooding is much less severe in Renton and causes far less damage than was the case in 1990,” he said. The airport no longer floods and a berm has reduced the severity of flooding on the golf course.

Flooding of the Cedar may not create vivid new memories, but old memories still make for dramatic stories.

Karen Curtis Knudsen lives in downtown Renton. She has lived through the the major floods in the city and heard family stories of earlier ones. Interestingly, she once heard a story from a friend about the flood of 1911, but she didn’t write it down because she thought it was the product of the woman’s illness.

She suggests checking out some of the homes in North Renton, on Park, Pelly  or Wells. Look for homes with four or five steps to the porch. They were trying to get to “high ground.”

Parts of Renton also were flooded by the Green River.

As a child in the late 1940s, Knudsen lived on a hill on what is now Valley Medical Center, so was above the flooding. But she watched as neighbors rowed to work. The rowers would tie up their boats to a telephone pole, then take another one to dry land. “They would do this day after day until the river receded,” she said.

There was one rule she learned in listening to the stories. Don’t tie up your boat without a slipnot. If not, as occasionally happened, a boat tied firmly would end up dangling from the pole.

“The boat and telephone were right across the street from the local tavern, so the men at the tavern had a good laugh at newcomer’s expense,” she says.

Today, the Cedar River is still not completely tamed, which many argue is OK.

The Masonry Dam still holds back millions of gallons of water, but there’s no way to stop the flow into the Cedar River from streams below the dam or from runoff.

Logs and debris still pile up against the city’s bridges during high water,  resulting in expensive efforts to remove them. The City of Renton and King County are working together to limit how often that happens.

But in 100 years man has made the Cedar a much better neighbor.

Cedar Controls

Following the historic storm of 1990, the City of Renton took several steps to ease the flooding of the Cedar River.

• Purchased large water bladders that are filled with water and placed along the river bank to protect old city hall and Carco Theater when needed.

• 1993, Renton dredged the Cedar River Delta.  While this did not alleviate flooding, it enhanced sea plane operation and reduced the threat of bird strikes at the airport.

• 1992, initiated the Cedar River Section 205 Lower River Flood Control project in coordination with the U.S. Army Corps of Engineers.

• 1995-1996, built an earthen berm along the river adjacent to the  Maplewood Golf Course to prevent flooding of the city-owned course.

• 1998, the Army Corps of Engineers, in partnership with the City of Renton, dredged the lower 1.25 miles of the Cedar River, increasing the cross section of the river and thereby the increasing the flow capacity.

• 1999, the Army Corps of Engineers, in partnership with the city, installed certified levees and concrete flood walls along the lower section of the Cedar River.  The Boeing Co. replaced the South Boeing Bridge across the river with a bridge that can be hydraulically jacked above the river level to protect it during flood events.

• The city periodically surveys the cross section of the dredged portion of the river to check on the status of the elevation of the river bottom and channel flow capacity.  Maintenance dredging will be performed to preserve the flow capacity of the lower section of the river.