Low-Impact Development Rules Sought to Reduce Contamination of Waterways

By Judith Nygren, Omaha World-Herald, Neb.

Feb. 17–A new emphasis on nature to control storm water runoff in the Papillion Creek watershed has won favor with communities in the Omaha metropolitan area.

So much so, the City of Omaha is preparing low-impact development rules to reduce the amount of storm water — and pollutants — rushing off land into already contaminated waterways. Other communities in Douglas, Washington and Sarpy Counties are expected to follow suit as part of their effort to adopt uniform policies for the watershed.

Many see low-impact development as a promising compromise for an area divided over the use of dams to control flooding. The latest water management proposal still calls for dams, but far fewer than once discussed — possibly no more than six to 15 when combined with low-impact development techniques. In the past, as many as 29 possible dam sites were identified in the three-county area.

The question now before elected officials and residents in the watershed is whether the new proposal strikes the right balance. The public will have a chance to weigh in during a series of open houses that kick off Tuesday at the University of Nebraska at Omaha.

Neither approach is cheap. Low-impact development would cost $530 million in today’s dollars to integrate into the landscape and maintain, according to an HDR study that calculated expenses over a 50-year period. The proposed dams carry an estimated price tag of $477 million.

Nor is either an all-purpose remedy to the area’s water woes. Low-impact development’s primary benefit is improved water quality. The most stringent development standards also offer flood control comparable to dams. But dams are the better choice for immediate flood prevention, the study concluded.

By combining the two approaches, the watershed can address its immediate need for flood control and its longer-range goal of protecting waterways, said John Winkler, general manager of the Papio-Missouri River Natural Resources District, which oversees the watershed.

“We’re actually coming to a middle ground” with the latest water management plan, Winkler said.

Clare Duda, chairman of the Douglas County Board, said he sees the latest plan as a “move toward common ground.” That doesn’t mean dam opponents will like it, he said. “But it’s a step in the right direction.”

Duane Wilcox, chairman of the Washington County Board, said the plan likely won’t change his board’s position: “We’re going to keep pushing and keep pushing for no dams.”

Washington and Douglas Counties opposed the earlier dam proposal and drafted their own water management plan, which included a low-impact development plan. Washington County worries that it could be home to the watershed’s largest dam, one of the reasons it never joined the Papio-Creek partnership of 11 other city and county governments.

Wilcox said Washington County understands the need for cohesive planning for the watershed.

“We’re all after the same thing,” he said. It’s just a matter of how best to get there — and Washington is confident it can do its part to control flooding and clean up waterways with low-impact development alone, he said.

Low-impact development works with the natural topography of an area to contain storm water on site, where it can be absorbed and filtered by the ground. The development options are numerous, including specially engineered swales and ditches, dry or wet retention ponds and water permeable materials for parking lots.

Lyle Christensen of HDR said developers would decide the best and most cost-effective method for retaining storm water within their subdivisions or commercial developments. But whatever method they use, it will cost more and require green space, he said.

HDR determined that the watershed, when fully developed, would need more than 1,000 on-site detention sites, each up to six acres, to handle a 100-year rainstorm — or 6.7 inches of rainfall in 24 hours, most of it during a two-hour period.

Omaha expects to adopt low-impact standards that would require developers to contain a minimum of a half-inch of water. Marty Grate, the city’s environmental services manager, said at that level, low-impact development only addresses water quality. More water would have to be retained to reduce flooding, he said.

While the watershed seems ready to embrace low-impact development, Winkler said, such development does little to address existing flood problems. That’s where dams enter the plan.

The plan identifies possible dam sites, ranking them according to their potential impact on flood reduction. The dam proposed for Washington County ranked among the most important.

Winkler said the partnership isn’t interested in building a dam opposed by local residents. The goal of the upcoming forums and ongoing talks with elected officials is to develop a plan that everyone can live with, he said.

But any community or county that says no to dams has to be prepared to adopt stringent low-impact development standards, then ensure they can’t be undone, Winkler said.

“We have to make sure it all fits together,” he said.

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Copyright (c) 2008, Omaha World-Herald, Neb.

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