After floods swept through Millvale three times in 1973 and 1974, the Army Corps of Engineers built a flood-control project on Girty's Run to handle wet weather flows.

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For almost 30 years, the work to straighten out the stream and stabilize its banks kept the flow out of the back yards and basements of those who lived creekside. But nine days ago Millvale got muddy and flooded once again, along with many other communities around Pittsburgh in the wake of Hurricane Ivan.

"The project is still working, but you could have put the town on the north rim of the Grand Canyon and it still would have flooded in that storm," said Millvale Mayor James Burn last week as he inspected a garage roof that the flood had lifted off its cement block walls and deposited in a neighboring yard.

Since 1948, the Army Corps of Engineers has built flood control projects in more than 40 communities in the upper Ohio River watershed in an attempt to keep the creeks and rivers that run through them from overflowing. More than a dozen of those are in and around Pittsburgh.

But when the rainfall measures in the 5- to 9-inch range in a day, flood control is more goal than reality.

"You can't design for Armageddon," said Werner Loehlein, chief of the corps' water management section. "The local flood-control projects don't eliminate flooding, but they do reduce the number and severity of flood events."

Although folks still dealing with buckets of mud and throwing out water-ruined possessions in Millvale, Etna, Carnegie and Canonsburg might disagree, most local flood-control projects worked as they were designed to until they were simply overwhelmed by what Fred Bigham, of the Chartiers Valley Flood Authority, called a "perfect storm."

Flow rates in Chartiers Creek exceeded the record set in 1912, not only causing flooding but also damaging the more than $17 million in flood-control infrastructure, including levees and bank stabilization, that had been installed from 1967 through 1980.

"The system worked well and surpassed its capability, but it was never built for this level of storm," Bigham said. "It was devastating. We don't know the extent of the damage yet, but [the flood control] will be put back into good shape."

Controls that worked

A series of flood-control measures on McLaughlin Run in Upper St. Clair, Bridgeville and Bethel Park were credited by officials in those South Hills communities with minimizing flooding there. Two 7-million-gallon storm drainage ponds captured a lot of rainfall even though they are still under construction.

In McKees Rocks, the Bottoms area was spared much of the flooding it experienced after previous storms because flood gates on lower Chartiers Creek worked to divert the flow away from developed areas.

In the Pine Creek, Little Pine Creek and Girty's Run watersheds draining the North Hills, a series of flood-control projects in the 1980s dredged and straightened the streams, cleared and stabilized stream banks and removed some floodplain obstructions that could catch debris during high flows.

The projects were designed to handle a 100-year flood, the kind of flood that has a 1-in-100 chance of happening in any given year. But Ivan's rainfall defied the odds and probably approached a 500-year flood event, said Bob Waigand, chief of emergency operations in the Army Corps of Engineers' Pittsburgh office.

"This was such an overwhelming event that the local project may have taken something off the top, but once the design parameters of a project are exceeded, you're going to have a problem," Waigand said.

Southwestern Pennsylvania is particularly susceptible to flood damage because of its steep-sided valleys veined with river tributaries, along with its heavy rains, quick snow melts, historic valley settlements and poor land use and development regulations.

The St. Patrick Day's flood of 1936, which put 12 feet of water in Downtown streets, killed 62 people, injured 500 and made 135,000 homeless, spurred building of the region's river flood-control system. That system includes 12 dams in the upper Ohio River basin on the Monongahela, Allegheny and Youghiogheny rivers and four more on the Beaver River watershed.

Dams limit damage

Altogether, the 16 dams control about 40 percent of the drainage area. They can't stop floods from occurring, but they can reduce their severity. Those multiuse flood-control and recreation reservoirs are complemented by the local control projects on tributaries.

"The dams did the job they were built to do. They substantially reduced the downriver flood crests," the corps' Loehlein said.

One of those flood-control projects, Crooked Creek Lake, on a tributary of the Allegheny River in Armstrong County, rose 55 feet as a result of the Ivan-spawned deluge.

"Obviously that's water that was not allowed to go downriver during the storm," Loehlein said.

Loehlein said the corps hadn't been able to calculate how much the dams and reservoirs reduced Ivan's flood levels. The rivers crested in Pittsburgh at 31 feet, six feet above the 25-foot flood stage at the Point.

Loehlein said the damage from tributary flooding after Ivan was exacerbated because the heaviest rains didn't occur high in the watersheds.

"If the storm centers had been up the rivers, behind our reservoirs, we would have captured more and reduced the flood stages more downriver," he said.

Waigand said the corps' Pittsburgh office had started to inspect 44 area flood-control projects for storm damage as part of a special federal program that provides funds for emergency restoration work. He hopes to complete some of that work before winter.

He said priority would be given to projects where there is the highest likelihood of flooding based on topography and the risk of significant property damage.

"We have teams out at this time and they will inspect and prioritize the work that needs to be done," he said. "If Etna or Millvale show up as having damages [to flood-control features], they will be a priority."

The corps had no plans to build new local flood-control projects on any tributaries in the region, but Waigand said the corps would reassess those plans after Ivan.

"Given the obvious need for improvements, we will work with local officials to identify where a combination of need and cost-sharing can come together," Waigand said, noting that such projects also require local sponsorship by a municipality or watershed organization.

He said Catfish Creek, a tributary of Chartiers Creek in Washington County, was reviewed by the corps after flooding last year and would be considered for a flood-control project after being "catastrophically impacted" again.

Waigand said projects to improve, channel or store storm flows are only part of the answer to avoiding flood damage. He said communities had to do more to reduce their flood exposure by limiting and managing floodplain development, and moving or adapting the use of structures already built along creeks.

"They need to take precautions so development doesn't make things worse over time," he said. "The urban center, where some of the worst flooding occurred, is well developed and doesn't have a lot of flexibility. But in the upper reaches of a watershed," he said, officials need to preserve wetlands, create storm basins or do other flood-control work, "or there will be some problems."

The corps and several state agencies regulate floodplain development to control storm runoff, but Waigand said decision-making and enforcement often fall to local governments.

"Political jurisdictions don't neatly overlap with watershed boundaries," he said. "And unless there's a watershed group being attentive to flood damage and natural systems, like wetlands to help control storm water runoff, those local governments might miss out on important ramifications of their actions for those living downstream."

A sign of the increasing development near rivers and streams is that, despite spending more than $30 billion on flood-control projects over the past century, losses due to flooding are now two to four times higher in comparable dollars than they were in 1900.