Perhaps the saddest part of the Issaquah Salmon Hatchery dam is watching red Coho attempt to jump it and land instead on a 10-foot buttress.

After surviving whales and fishermen and then even leaping the hatchery wall – they finish their journey not by spawning but breathless and stranded.

The dam is essential for keeping the hatchery flowing with water, and Jane Kuechle, director of Friends of the Issaquah Salmon Hatchery, couldn’t be happier to see it go.

It’s being replaced by a $4 million system of weirs, low dams with pools that will make it easier for the salmon to move upstream. Not only will the new system make it easy for salmon, it also means cleaner water for the hatchery.

“The idea behind it is to make the stream more of a stream,” Kuechle said.

The project has been on Washington Fish & Wildlife’s wishlist for a while, but the state Legislature didn’t approve funding until this year.

It’s one of the many things FISH plans to celebrate at the hatchery’s 75th anniversary on Sept. 8.

The current dam, a state-of-the-art design in 1937, received a buttress several years ago to keep it from collapsing. It also was modified with a fish ladder, but instead of using stacking pools with short steps, engineers essentially built a staircase with water flowing down. Some salmon make it, but many don’t.

On an August morning, Kuechle points to the 10-foot-deep buttress. A thin layer of water flows over the top, testimony, Kuechle says, that conditions are dryer than last year. A few days later, the first Coho made its return to the hatchery, about a quarter mile down stream.

A choke will sit upstream from the weir system. The choke will be deep enough to collect the water needed to fill the hatchery pools and run over the fertilized eggs.

Silt from years of mining and new construction still comes down the Issaquah Creek. It’s a concern for the hatchery because too much silt can suffocate the salmon eggs. Hatchery workers constantly have to clean them. The new system would significantly reduce silt.

Construction is slated for the winter, during the couple month window that least impacts the fish. The hatchery is working on a plan for getting water to its tanks during the construction, but one idea is to reduce its collection by sending fry to other hatcheries.

75th year anniversary celebration

Friends of the Issaquah Salmon Hatchery is hosting a 75th anniversary celebration from noon to 4 p.m., Sept. 8.

The community event is scheduled to include several activities including a tribute from the Snoqualmie Tribe, tours of the hatchery and dam, and a wood-carving demonstration.

Activities for kids include feeding the trout, a salmon dissection and creating fish-print shirts.

The event is free to the public and centers at the Issaquah Hatchery, 125 W. Sunset Way.