The discovery last week of spawning coho salmon north of Union Street is a victory for local biologists and watershed advocates who pushed more than a decade for a special culvert buried at the intersection at Sixth Avenue in 2008.

“It’s a huge success. It proves these fish passages are important and they work. We’ve opened habitat for spawners, which is rare for an urban area,” said Emily Cowles, executive director of the Takshanuk Watershed Council.

Fish and Game sport fish biologist Rich Chapell found eight spawners last week in a forested section of the creek on private property about 900 feet north of Union Street. He’s also found mature coho carcasses.

“We know it’s been a major rearing area. It’s clear, slow-moving water, which is what juvenile coho love. Now we know adults use it, and (their progeny) will either rear up there or migrate out, but they’re free to move in and out as they need to,” Chapell said.

The discovery marks the first time in decades spawning salmon have gone so far upstream in Sawmill Creek, a stream that drains the west side of the townsite and once linked Jones Point with Portage Cove. Restoration efforts have been under way since the late 1980s.

Former sport fish biologist Randy Ericksen started pushing for culvert improvements in the early 1990s, when the City of Haines mistakenly filled a section of the stream above Union. At that time, only resident cutthroat trout were found there.

The story about the fill landed Ericksen in Alaska Magazine, but it also brought attention to the project, which was funded by the state but delayed to coincide with paving of Union Street two years ago. The $150,000 project included a 300-foot culvert with baffles that slow stream flow and ease fish passage.

Ericksen found spawning and rearing coho just downstream of an old, crumbling, dog-legged culvert that ran beneath Union then crossed Sixth Avenue. Ericksen, who now works for the Portland, Ore.-based Wild Salmon Center, said the need for the project was evident.

“They’d obviously blocked fish passage upstream and there was a fair amount of habitat there. (DOT) had to do something with that culvert. If you’re going to do something, you might as well do it right,” Ericksen said this week.

Biologist Chapell said coho are opportunistic spawners that will deviate from returning to their home streams in favor of better habitat. Heavy rainfalls that increase flows, like ones in recent weeks, also tend to push coho farther up streams and into new ones, he said.

That might also help explain the discovery a month ago of 10 coho on two tributaries of 1 Mile Creek (also called Holgate Creek) near radio towers on FAA Road by watershed council biologist Dan Schultz. Those fish, from Chilkat Inlet, appear to have made an impressive swim uphill including scaling a makeshift fish ladder near 1 Mile Mud Bay Road, then passing through culverts under Mud Bay and Small Tracts roads.

A former “perched” culvert under Small Tracts was lowered to increase fish passage, a factor that may have helped the salmon make it to FAA, Ericksen said.

Ericksen said he was heartened by the news that efforts he and others started two decades ago are paying off. “It’s really gratifying. It’s a big step, and it’s not only about improving access for fish. Once they get up there, they’ll dig down through the silt to find spawning gravel. It improves the habitat, just them digging around in it.”

Eggs from coho that spawn this year will emerge as fry in the spring. The juveniles will spend next summer and winter in fresh water before heading out to sea in June 2012, then returning as adults to spawn in 2013.

Approximately 89,000 coho made it to spawning grounds around Haines this year, a bumper run for the state, which sets its escapement goal at between 35,000 and 70,000 fish.

The run was about two weeks late, with peak counts on spawning grounds in late October, biologists said.