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story.lead_photo.caption Water crests over War Eagle Road April 30 near War Eagle Mill in Benton County east of Rogers. - Photo by NWA Democrat-Gazette file photo / BEN GOFF • @NWABENGOFF

Floodwater doesn't respect municipal boundaries, so planners say a regional approach to flooding is needed as Northwest Arkansas continues to grow.

Jane Maginot, a water quality expert with the University of Arkansas System Division of Agriculture Cooperative Extension Service, said she and her peers usually look at water quality but decided someone needed to look at water quantity, which led to a committee being formed to consider a regional approach to flood prevention and management.

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Flooding

The changes in land use associated with urban development affect flooding in many ways. Here are a few from a U.S. Geological Survey fact sheet:

• Removing vegetation and soil, grading the land surface and constructing drainage networks increase runoff to streams from rainfall and snowmelt. As a result, the peak discharge, volume and frequency of floods increase in nearby streams.

• Changes to stream channels during urban development can limit their capacity to convey floodwater. Roads and buildings constructed in flood-prone areas are exposed to increased flood hazards, including inundation and erosion, as new development continues.

• Streams are fed by runoff from rainfall and snowmelt moving as overland or subsurface flow. Floods occur when large volumes of runoff flow quickly into streams and rivers.

• The peak discharge of a flood is influenced by many factors, including the intensity and duration of storms and snowmelt, the topography and geology of stream basins, vegetation and the hydrologic conditions preceding storms.

• Land use and other human activities influence the peak discharge of floods by modifying how rainfall and snowmelt are stored on and run off the land surface into streams.

• In undeveloped areas such as forests and grasslands, rainfall and snowmelt collect and are stored on vegetation, in the soil column or in surface depressions. When this storage capacity is filled, runoff flows slowly through soil as subsurface flow. In contrast, urban areas, where much of the land surface is covered by roads and buildings, have less capacity to store rainfall and snowmelt. Construction of roads and buildings often involves removing vegetation, soil and depressions from the land surface. The permeable soil is replaced by impermeable surfaces such as roads, roofs, parking lots, and sidewalks that store little water, reduce infiltration of water into the ground, and accelerate runoff to ditches and streams.

• Dense networks of ditches and culverts in cities reduce the distance that runoff must travel overland or through subsurface flow paths to reach streams and rivers. Once water enters a drainage network, it flows faster than either overland or subsurface flow.

• With less storage capacity for water in urban basins and more rapid runoff, urban streams rise more quickly during storms and have higher peak discharge rates than do rural streams. In addition, the total volume of water discharged during a flood tends to be larger for urban streams than for rural streams.

• Sediment and debris carried by floodwater can constrict a channel and increase flooding. This hazard is greatest upstream of culverts, bridges or other places where debris collects.

• Common consequences of urban development are increased peak discharge and frequency of floods. Typically, the annual maximum discharge in a stream will increase as urban development occurs.

Source: Staff report

"It kind of came up to start talking about this idea of regional floods, not just as in flood control but flood help, how to help other communities that are having issues with flooding and how to help them try to not have as many flooding issues," Maginot said recently. "We thought why don't we pull together some people and see what the interest is. Are there communities out there that can benefit from some kind of regional flood management program? That's really what today is, it's just a starting point to determine the interest and the feasibility and what that might start to look like."

Other metro areas, including Las Vegas, Houston/Galveston and the central valley area of California have taken up flooding from a regional perspective, Maginot said.

Studies have shown that if it rains 1 inch over an acre of forest you get about 720 gallons of runoff, Maginot said. If it rains over an acre of parking lot, you get 27,000 gallons of runoff.

About 40 representatives from area towns, cities, Washington and Benton counties and water-related organizations gathered a couple weeks ago at the Northwest Arkansas Regional Planning Commission to discuss potential benefits and obstacles of a regional approach.

Several major floods have hit areas of Northwest Arkansas in the past decade and planners expect things to only get worse as more people move here and more homes, commercial areas, roads and parking lots are built.

Flooding costs region millions

Flooding in recent years tore apart a golf course in Bella Vista, poured through houses in Johnson, floated a minivan on the main drag in Lincoln and damaged bridges and roads in rural areas. Two people, a little girl and an elderly man, recently drowned after being swept away.

The cost of the destruction keeps rising. For example, damage in April 2011 was estimated at $3.5 million to public facilities in Washington County and about $1 million in Benton County. In April 2013, flooding caused about $4 million damage to public facilities in Benton County. In December 2015, an estimated $2 million damage was done to roads alone in Benton County. Amounts have not been estimated for this spring's flooding in the region.

Residents also are reporting flooding in areas that never used to flood.

"We're seeing that more and more frequent. I've worked for Bella Vista for eight years, and we've had just about as many floods," planning director Chris Suneson said.

Kevin Gambrill, with Benton County planning, said county issues relate to being downstream and the water keeps getting higher.

"We have some particular hotspots. The unincorporated county ends up getting the brunt of the runoff that comes from the cities," Gambrill said. "USGA stream gauge data history is getting bigger and bigger during each of these events. I have 9- and 10-foot high water marks in a particular neighborhood. It's not getting any better."

Gambrill said anything that can be done upstream to reduce flooding would be beneficial and at least maintain the status quo.

Nathan See, with the city of Pea Ridge, said his city's problems are the opposite.

"A lot of that problem we have is coming from the rural areas carrying those trees and stuff," See said. "It's gonna grab all that stuff and bring it down to the Peck Road bridge and just close it up. That debris is ridiculous. We've got to get into where this problem is actually coming from."

See said once the bridge on Peck Road over Little Sugar Creek in the southeast part of town is clogged water goes over the bridge and also back up to flood adjacent areas, including parts of Big Sugar Golf Club.

Gambrill said he has tallied flooding calls to emergency management.

"When I looked at it on a map, it's very random, it's very spread out. The water decides it's going to go to the lowest spot and it's gonna impact an old development. It's everywhere. There's absolutely no pattern to whether it's in a floodplain or not in a floodplain," Gambrill said. "It's truly random, at least based on a sample."

Changing to a regional mindset

Historically, each local entity has tried to deal with flooding issues in its own way, without regional coordination.

"We need regional stormwater detention," said Jerry Morrow with the city of Johnson. "Creeks don't care about city limits, creeks are going to do what they do and if you keep increasing hard surface, you're gonna increase runoff. This is not a new problem, it's new to us [Johnson] because we're just now growing and all indications are we're going to keep growing. Now is the time to set measures in place to fix it so it doesn't happen."

Morrow said flooding in April was such an extreme event it's probably not financially feasible to try and build for a repeat, but cities can plan and build for more typical flooding events.

"Set up regional detention. Set up channelization. You can do various things," Morrow said. "Everybody's got to work together on this."

Morrow said engineers are typically designing subdivisions to meet minimum city requirements and don't look at the cumulative effect downstream.

"Many of the ordinances in place are creating the problem," Morrow said.

Fixing the problem promises to be expensive and with many other pressing issues, finding money could be the biggest obstacle, said Don Marr, chief of staff for the city of Fayetteville. Northwest Arkansas doesn't have a regional stormwater management utility or anything that could be established as a source of money other than a general sales tax, Marr said.

"I think the challenge is the funding, because no one's general fund can handle the kind of capital requirement needed to reduce it immediately," Marr said. "We have identified $13 to $15 million worth of drainage improvements that could be done. That's two years of our CIP, a hundred percent of it. There has to be a funding solution developed."

Marr said another obstacle is that residents don't take kindly to city officials spending their tax dollars on regional projects outside city limits when they've got plenty of issues in their own town to deal with.

"They're all going to get un-elected," Marr said.

A regional approach may be the only way to help smaller cities, with their equally smaller budgets.

"At the end of the day, if the money's not there, the smaller cities can't do it." said Al Videtto, with the city of Lincoln.

Gary Blackburn, mayor of Garfield, said the reality is his town would need outside help to participate.

"Garfield's 502 [residents], and we've got a backhoe and tractor," Blackburn said. "We couldn't hardly get anything done if it weren't for intergovernmental work with Benton County."

Morrow suggested developers could be charged a fee or a surcharge could be added to water bills to help pay for drainage improvements.

Videtto said rural water is already expensive.

"West Washington County has some of the highest poverty rates in the state," Videtto said. "We've got to remember when we're doing this there are people who are barely feeding themselves, and if we put a high fee on their water then we might create more problems in other areas for them."

Charting a path

Whatever the group ultimately comes up with needs to be applied uniformly by every entity to be effective and to make sure no one is put at an economic disadvantage, several members said.

Videtto and others said there's stiff regional competition to attract new businesses and jobs. Stricter development requirements typically drive up the costs of locating a new business and if it's cheaper in the next town over, a business may choose to go there instead.

"I think there is a real economic development reality to that, and people use it against you to say you're over-regulating, you're creating more fees, we're going to go to XY community and not develop in yours; it becomes very difficult politically," Marr said. "The reality of it is you have to balance that with knowing other places don't have that and you're competing with them."

Maginot said she was pleased with the turnout and the amount of interest shown by the representatives at the meeting.

"There's at least a problem; we all agree on that," Maginot said. "So there's gotta be some kind of way to go forward, whether it's an idea we can shoot for the stars or try to find out some smaller ways and smaller avenues as starting points."

The group is expected to meet again and will likely form a subcommittee to explore how to best address regional flooding issues in Northwest Arkansas.

The group wants to look at what scope of work the U.S. Army Corps of Engineers will allow to be done in streams and what can be done when problems, such as blockages, arise on private property.

"It turns into a very complicated issue; you've opened up a can of worms there with who owns it and who regulates it," Morrow said.

Other ideas included public education campaigns on what individual homeowners and property owners can do to protect themselves from flooding as well as to protect those downstream, working with cities on training for flood mitigation and scout opportunities for updated or improved drainage manuals and criteria or initiating such changes.

The group also tossed around the idea of model ordinances cities could adopt, exploring whether a regional utility or authority to deal with the issue, a possible master plan for Benton and Washington counties and a simple memorandum of understanding each entity in the region could execute.

"It would become a binding agreement. It may just be we all agree to study certain things," Morrow said. "I mean it takes away the issue of who's the first person in the water, the first one to get shot."

NW News on 07/09/2017

Print Headline: Planners seek regional approach to flooding

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