Environmental concerns are making it less likely that even a portion of Napa Creek flood protection could start construction next summer.

State and federal natural resource agencies are questioning elements of the flood control plan crafted by the U.S. Army Corps of Engineers, Julie Lucido, the local flood district’s principal engineer, reported.

Until concerns over tree removal and bank riprap are resolved, the corps has stopped designing the project and the local flood district has suspended property acquisition.

This was bad news for members of In Harm’s Way, the neighborhood group representing homes and businesses in Napa Creek’s flood zone.

This is another in a long series of delays that may leave the neighborhood vulnerable to flooding for additional years, Linda Kerr, a group spokesperson, said.

In Harm’s Way once believed that construction could start this year, Kerr said. This latest complication could push the first phase to 2010, she said.

At last week’s flood board meeting, several members voiced frustration that these environmental concerns were surfacing at seemingly the last minute.

“I really want to vent on this,” Napa Councilman Jim Krider said. “I know we’ll all lose sleep if it rains this winter.”

Julie Lucido, the local flood district’s principal engineer, said this latest delay was unfortunate, but understandable.

The Corps of Engineers recently tweaked the creek design, taking into account new assumptions about water velocities in a so-called 100-year flood, Lucido said.

The new design takes note of the flooding that occurred on New Year’s Eve, 2005, Lucido said. The corps deemed that natural disaster to be a 70-year flood, she said.

To protect the banks and planned culverts from higher-velocity flows, the corps added more bank “armament” and tree removal, Lucido said. Despite these alterations, “we’re not clear-cutting by any means,” she said.

These changes caught resource agencies such as state Fish and Game, the Regional Water Quality Control Board and the U.S. Fish and Wildlife Service off guard, said Heather Stanton, manager of the local district. “They have to be educated on the changed assumptions,” she said.

A meeting is set for Oct. 20 between the corps, the resource agencies and the local flood district, which hopes to serve as a “conciliator,” Lucido said.

The district has hired Ric Reinhardt, a hydrologic consultant, to analyze the new flood data and recommend solutions, she said. Reinhardt worked for the corps when the Napa flood project was being designed in the late ’90s.

Because the design disagreement focuses on the middle and upper stretches of the creek, In Harm’s Way asked the flood district last week to push for work to begin on the lower creek near Main Street next year.

The local flood district and the city of Napa have been seeking grants to start lower creek construction sooner than corps funding would allow.

Unfortunately, no work can start on any portion of the creek until the resource agencies and the corps reach agreement on the entire design from the Napa River to almost Jefferson Street, Lucido said.

The design calls for dual culverts at the west end near Behrens Street and at the east end near Main Street. Flood terraces are planned for the north bank near Arroyo Drive. The culverts would carry half the flow of a major flood.

While Napa Creek defenses are being designed, the corps is overseeing a recently awarded $65 million contract to relocate Napa Valley Wine Train tracks east of downtown and build two railroad bridges. This work is expected to take three years, assuming timely federal funding.

After the rail work is finished, the corps will shift its attention to Napa Creek and construction of a flood bypass channel near the Wine Train station on McKinstry Street.

At the request of In Harm’s Way and the local flood district, the creek work, estimated to cost $20 million, has priority over the bypass.