The federal government has blocked repairs to a second tidegate in Skagit County, Wash., reasoning that maintaining the structure will forestall the conversion of farmland into fish habitat.

The Army Corps of Engineers notified the National Marine Fisheries Service on Sept. 4 that repairing the century-old tidegate likely will adversely affect Puget Sound salmon and killer whales.

NMFS will now conduct its own review. NMFS in April found tidegate repairs proposed by another Skagit County drainage district would jeopardize salmon and killer whales, which prey on salmon.

A dozen diking and drainage districts oversee a network of dikes, pumps and tidegates that make farming possible in the low-lying Skagit Delta, about 60 miles north of Seattle.

Tidegates keep Puget Sound saltwater from flooding farm fields. The corps and NMFS have taken the position that extending the life of tidegates deprives salmon of essential habitat.

NMFS issued a biological opinion in April stating repairs to a tidegate proposed by Skagit County Dike, Drainage and Irrigation District 12 would jeopardize the existence of Puget Sound salmon and killer whales.

District 12 has filed suit in the U.S. District Court for Western Washington, claiming NMFS overstated the project’s impacts.

The nearby Skagit County Drainage and Irrigation District 19 proposes to line seven leaking century-old concrete pipes to keep a tidegate from collapsing. The district’s system drains 3,418 acres of farmland.

The 48-inch diameter pipes have been in place since about 1922. The pipes drain water into Padilla Bay and snap close to keep out salty high tides.

The district proposes to plug leaks by lining each pipe with a 3-foot-diameter plastic sleeve.

“We’re not going out and taking new land,” district commissioner Jason Vander Kooy, a dairy farmer, said Friday. “We just want to maintain what we have. It’s no different than fixing a pothole.”

The district submitted to the corps a 20-page biological assessment of the project. Repairs would be made at low tide and in dry weather, according to the district.

The corps agreed the repairs would prevent a “catastrophic failure” and maintain farm fields, described in a letter from corps Branch Chief Todd Tillinger as “existing habitat conditions.”

But preventing a catastrophic failure and maintaining existing conditions concern the corps, according to Tillinger’s letter to NMFS Assistant Regional Administrator Kim Kratz.

“The existing habitat conditions reduce the availability of estuary nearshore and floodplain habitat along Padilla Bay,” the letter reads.

Skagit Delta agriculture will be in trouble if districts can’t maintain tidegates, Vander Kooy said.

“Without agriculture, we’re King County,” he said.

Efforts to obtain comment from NMFS were unsuccessful.