Future of muddy water not yet clear

By Sarah Brown
Lebanon Local

Since a court-ordered deep drawdown of Green Peter Reservoir that began this Fall, Lebanon has been working overtime to maintain safe drinking water for the community.

During the Nov. 8 City Council meeting, Public Works Director Jason Williams showed a sample of raw water from the Santiam River intake faucet alongside a sample of finished water from the water treatment plant.

“Our raw water source on the South Santiam River is typically one of the cleanest sources for NTU (nephelometric turbidity unit),” Williams told the council.

NTU is a measurement of water clarity. According to Williams, the City’s permit limit for drinkable water is less than .30; once drinking turbidity reaches higher than that, Oregon Health Authority would get involved.

According to Williams, the raw water’s NTU a year ago – Dec. 1, 2022, following one of the city’s biggest storm events – measured 31 (the highest turbidity number of the year) and, after filtering, measured .016. On Nov. 8, 2023, the NTU measured 281 and, after filtering, measured .14.

The tailrace at Green Peter Dam releases water full of silt on Nov. 11.

“Basically we’re taking the bottom of Green Peter Reservoir and all the silt that’s drained off from every tributary and creek that comes into that lake, and we’re bringing that right down the South Santiam River,” Williams said.

Engineering Director and Interim City Manager Ron Whitlatch said Albany reported an NTU of 100 on the same day Lebanon rated 200. As for Sweet Home, he originally believed their water wasn’t as murky as Lebanon’s because Sweet Home draws water from deep within the reservoir, but Williams told Lebanon Local they learned the mountain community’s turbidity numbers are similar to Lebanon’s.

To properly clean the water for consumption, the City of Lebanon is now operating the water treatment plant 24 hours a day, a process that’s “extremely hard” on the membranes, Williams said. That means the membranes will need to be replaced at a faster rate than usual. Additionally, staff are cleaning membrane racks four times more often than usual, Williams told Lebanon Local.

These processes are raising costs for chemical supply and staffing hours, he said.

The membranes are currently on a 10-year replacement cycle, but no one knows how long they’re going to last with this new process, Whitlatch said.

Williams shows a sample of raw water compared to treated water.

However, despite some cloudiness or color “issues,” the water is safe to drink, Williams said.

“We’re making absolutely safe drinking water. We’re not even close to any violations for our OHA issue permit,” Williams said.

Whitlatch noted that if the City was still using the old water treatment plant (which is being demolished this month), the city would be on a “boil” notice.

“The old plant, there’s no way it would be able to handle it,” Whitlatch said.

Whitlatch said there’s gonna need to be some discussions through state legislatures about the muddy water issue. It’s not a sustainable process, he said.

On Nov. 15, Oregon’s District 5 Representative Lori Chavez-DeRemer released a letter issued to Chief U.S. District Judge Marco A. Hernández urging him to reconsider how best to preserve fish passage at Green Peter.

A 2021 order from the federal judge requires Green Peter Reservoir be drawn down approximately 140 feet below typical winter reservoir levels by mid-November in an effort to pass young Chinook salmon and steelhead downstream.

A lone bench at Riverview Park overlooks the South Santiam River as it passes through Lebanon on Nov. 4.

As the reservoir emptied through the dam’s regulating outlet near the bottom of the structure, thousands of young Kokanee salmon died from barotrauma and floated down to Foster Lake. When water levels began reaching its lowest point since the 1960s, silt from the many tributaries and the reservoir turned a once clear water source into what now looks like coffee with a lot of cream.

Next up: hydropower

Meanwhile, a different study is taking place by order of Congress, which has the potential to result in the elimination of hydropower from Green Peter, Foster and/or other federal dams operated in the Willamette Valley.

An outlet, called a “penstock,” routes water through the dam and past turbines that generate electricity, which is transferred to and distributed by Bonneville Power Administration. The turbines have been reported to cause injury and death to a number of fish passing through them, but Kelly Janes, USACE senior planner and public involvement specialist, also noted the turbines reduce dangerous gas levels. The penstock itself provides benefits such as temperature regulation and upstream migration.

The Water Resources Development Act of 2022 directed the Portland District to complete a report to Congress containing information on a determination of federal interest in, and to identify the effects of, removing hydropower production as a purpose – in whole or in part – from the Corps’ Willamette Valley system of dams.

“We’ll be looking at several scenarios in the report to Congress,” Project Technical Lead Kathryn Tackley said during a listening session in September. “These include partial deauthorization, meaning the turbines would provide station service power for the dam and for our facilities only; so no power would be marketed. The second scenario is full deauthorization and decommissioned penstock, and the third scenario being evaluated is full deauthorization with reconfigured penstock, meaning that we reconfigure the penstocks to allow for the continual release of water through those outlets.”