Senior U.S. District Judge Marco A. Hernandez issued an order Sept. 24 that will guide a modified deep drawdown from Oregon’s Green Peter Reservoir this fall — with a delayed start and faster flow than 2023.

Officials expressed concern with last year’s water releases, which were designed to improve passage for endangered salmon but ended up muddying rivers, tainting drinking water and stressing facilities for downstream communities.

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The drawdowns occurred for the first time last year at Green Peter and Lookout Point dams in the Willamette Project, the result of an injunction issued in 2021 by Hernandez in a case brought by environmentalists.

Hernandez recently approved a revised fall downstream fish passage implementation plan brought forth by the defendants, who consulted with federal and state agencies as well as cities to try to lessen the impact of the drawdowns.

Officials are bracing for this year’s release.

“We know what’s coming and we feel like it’s going to be very similar to last year,” said Ron Whitlatch, interim city manager and engineering director for the city of Lebanon, Ore.

Whitlatch added he was concerned about long-term damage to Lebanon’s $38 million water treatment plant, built in 2018.

The city paid $20,000 to $30,000 in overtime and extra chemicals to deal with the muddy water, which clogged filters and other equipment.

Over the summer, Lebanon also purchased $450,000 in additional membrane filters, dipping into its maintenance savings for the facility.

There’s been no financial help from the government for the problem.

“It’s really frustrating,” Whitlatch said.

Thousands of fish flushed through Green Peter Dam in 2023 also were killed by barotrauma, a rapid and extreme change in pressure. Elevated turbidity from sediment and higher water temperatures in the river also likely stressed aquatic life.

Modifications to the drawdown this fall aim to improve water temperatures and enhance turbidity monitoring and communication.

Delayed start, faster flow

Water releases from Green Peter will be delayed until the average surface water temperature has cooled below 64.4 degrees, which typically happens in mid-October.

The water flow will be increased during the drawdown, limiting the timeframe of water releases by 11-26 days.

That also should limit the duration of elevated turbidity, though similar peak levels as 2023 are expected.

The operation will be paused or terminated if flood risk management operations are necessary, if downstream drinking water facilities are unable to meet water supply demands or if a public health emergency is declared, such as a boil water notification.

The target elevation of 780 feet should be reached between Nov. 15 and Dec. 1.

In 2023, that level was reached Nov. 2. The reservoir hadn’t been dropped so low since it became operational in 1967 because that’s the minimum elevation necessary to generate power.

Officials respond

The Linn County Board of Commissioners would have preferred the federal judge vacate his order.

“We do think that the modification of the previous plan to mitigate the impacts is positive if it works,” Commissioner Roger Nyquist said.

“The open question is, if the current plan affects public health and local government requests they suspend the activity, will they do it?” Nyquist asked.

Whitlatch also wondered who would approve shutdowns.

“If we’re to that point, it’s too late, because you’re not clearing up the water quality for weeks,” Whitlatch added.

Meetings, emergency declaration

The U.S. Army Corps of Engineers has scheduled online information sessions about the water releases for Green Peter and Lookout Point dams Oct. 9 and 11.

Online information sessions

Wednesday, Oct. 9

Session #1: noon – 1:00 p.m.

Session #2: 5:00 p.m. – 6:00 p.m.

Friday, Oct. 11

Session #3: noon – 1:00 p.m.

Join online: https://usace1.webex.com/usace1/j.php?MTID=m76365654edf175e73457a0803292a29b

Join by phone: 1-844-800-2712

Meeting number/access code:2822 001 1537

Meeting password: nyDBJE5x?92

The Lebanon City Council is set to vote at its Oct. 9 meeting to declare an emergency due to water quality issues and their financial impact.

Whitlatch said Lebanon and the city of Sweet Home continue to consider litigation, as well.