SPRINGFIELD — As homeowners repair damage caused by flooding on Lake Taneycomo, some are asking how a lake that had not flooded significantly since the construction of Table Rock Dam in the late 1950s could inundate their homes three times in three years.
"What's different?" asked Mike Long, who said he had to gut his home, where water got four and a half feet high.
He believes Branson Landing, a shopping and dining development built just downstream from his house in 2006, could be a cause.
"It restricts water flow," he said. "When it rains, the water can't get around it."
Branson Building Plans Examiner Tim Bonner said the Landing is not at fault, but development on a broader scale could be.
Bonner said when Branson Landing was built, developers had to meet Federal Emergency Management Agency requirements and document that the project's footprint would not significantly affect the lake level.
"Their engineers did a hydrological analysis that showed it would not raise the lake a foot," he said.
Rick Huffman, CEO of HCW Development Co., the company that developed Branson Landing, said the Landing is not the cause of more flooding problems.
"It's just the opposite," Huffman said. "With the seawall there and with the boat docks removed, it actually flows better."
He confirmed that HCW had to have hydrological studies done to show that the project would not significantly affect the lake level.
However, Bonner said development across the entire White River watershed can add up to a problem.
"If you think about the amount of rain and all the impervious surfaces, such as roads and parking lots, there is a lot more runoff than we had 10 or 20 years ago," Bonner said.
Rather than soaking into the ground, being absorbed by plants or taking its time working its way through pastures and forests, water zips across rooftops and pavement and goes quickly into the lake.
Gopala Borchelt, executive director of Table Rock Lake Water Quality Inc., said development can make a surprising amount of difference.
"Ten percent development of a watershed area increases runoff by double," Borchelt said
The nonprofit group is studying water runoff as part of a federal and state grant. She said many residents and businesses that try to build detention basins discover how much runoff there is.
"If we get a heavy rain, the detention basin is just blown away," she said.
Table Rock's watershed includes the James River watershed, which drains most of Springfield and fast-growing cities such as Ozark and Nixa.
P.J. Spaul, a spokesman for the Little Rock Office of the U.S. Army Corps of Engineers, said there have been no comprehensive studies about runoff changes due to development, but there is bound to be some difference.
"Of course, stormwater will run off of a roof, a parking lot or a street faster than through a forest floor," Spaul said.
He said it can also contribute to localized flash floods, which are responsible for more deaths than river or lake floods.
"But if development is done correctly, with stormwater in mind, a lot can be mitigated."
That mitigation, such as open spaces, retention ponds and riparian corridors — tracts of vegetation near a waterway — is of major concern to the James River Basin Partnership, Project Manager Melissa Bettes said.
"There's a lot of development you can do where you can have the same thing with a smaller footprint," she said.
Springfield Public Works Stormwater Engineer Todd Wagner said much has been done over the years to help the situation.
"Anything built in Springfield since 1983 would have detention requirements," he said.
He said growing communities around Springfield have also had to meet detention requirements mandated by the Environmental Protection Agency.
"They don't eliminate all the effects (of stormwater) but they do hold it back and mete it out more slowly," he said. "Over the last 20 years, I don't think there's been a dramatic change in runoff."
The one thing everyone seems to agree on is that rainfall amounts have been so great that flooding was inevitable.
"In 2008 and again this year, the storms just lined up along the White River Basin," Wagner said. "The planets couldn't have lined up better against it."
Spaul said almost all areas in the White River basin received 12 to 22 inches of rainfall the last weekend of April. Many areas received another big dose of rain in May.