The 58-foot-wide concrete channel, which extends upstream to the Canadian Pacific Railway bridge, is severely deteriorated and its removal will allow stronger swimming fish — salmon, walleyes and even northern pike — to push up the river to Menomonee Falls.

After that work is completed this summer, MMSD intends to eliminate five additional obstacles — all in Wauwatosa — for redhorse and other fish swimming up the river, easing their way even during low flows of summer, said Tom Chapman, district watercourse section manager.

The barriers to those weaker swimmers are an old dam and road that no longer serve a purpose and a sewer. Each of the obstacles spans the full width of the river channel.

Removing the obstacles will open 17 miles of the main river — through Wauwatosa to Lepper Dam at Mill Pond Park in Menomonee Falls — to fish migration.