Drainage in Lowell evaluated

Fish vulnerable, karst study says

LOWELL -- Maps detailing the results of the Cave Springs Karst Study fill a wall in Richard Stone's office at Lowell City Hall.

The Lowell utilities director has spent months attending meetings and going through documents to better understand how results from the study released in July could affect the city.

The Nature Conservancy describes the Ozark karst as a system of caves, springs and aquifers with porous terrain that is susceptible to pollution.

The study by Ozark Underground Laboratory states that certain types of development in some areas affect a threatened population of blind Ozark cavefish in the karst ecosystem. Those areas fall in the city limits of Lowell, Rogers, Cave Springs and Springdale.

"The fish are the canary in the cave," Stone said. "If they die off, it is a sign about our water quality."

The Northwest Arkansas Regional Planning Commission contracted Crafton Tull -- an Arkansas architecture, engineering and surveying firm -- to partner with Ozark Underground Laboratory and Wright Water Engineers to conduct the study.

Tom Hopper, Crafton Tull's board chairman, said soil type, land slope and the location of streams all help explain why drainage from some land affects the fish population more.

The study outlines four zones to describe the vulnerability of the fish population, Hopper said. Vulnerability levels can be either extremely high, high, moderate or low.

Most of Lowell falls into the extremely high vulnerability or high vulnerability zones, Hopper said.

"Lowell and Cave Springs are most affected by this study," Hopper said.

Hopper recently told the Lowell Planning Commission that he recommends the city adopt a 10-chapter drainage manual similar to one already being used in Rogers. The manual outlines how developers should manage water runoff.

All changes should come with a grandfather clause, Hopper said.

It will take some time to go through the manual and rewrite it for Lowell, Stone said. He said developers should notice only slight changes.

Hopper said the city already requires developers to take measures to address runoff, including building detention ponds and adding greenspace. Changes could include where the greenspace and ponds are located.

Rogers approved most of its manual in 2012, said Lance Jobe, the city's project engineer.

"Our previous one was from 1993," Jobe said. "We thought it was time to update. Practices had changed over the years some."

The changes included developers providing a city easement around detention ponds, Jobe said. The easements allow the city to fix drainage problems if a pond fails for reasons that Jobe said could include a backed-up pipe causing the pond to flood.

It also required developers to research and plan for water runoff in a different way, Jobe said. He said the city previously required developers to plan for "two-year" flooding events, which have a 50 percent likelihood of happening in any given year. It now requires developers to plan for "one-year" events, or flooding that Jobe said the city expects every year.

Development hasn't seemed to slow since the drainage manual was adopted, Jobe said.

"Development is still increasing year over year since the recession," Jobe said. "It doesn't appear to be a huge determent to development."

Hopper said other cities adopting the Rogers manual will keep things uniform for developers.

"In most cases in [Northwest Arkansas], developers are competing based on the same rules," Hopper said. "As long as you are competing on a level playing field, they are willing to meet those guidelines."

Metro on 11/23/2015

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