Last month, the U.S. Army Corps of Engineers announced it would halt the drawdown of the Green Peter Reservoir on the South Santiam River.
The decision seems to have come in response to the nearby cities of Sweet Home, Lebanon, and Albany who say the drawdown is having a negative impact on their water supply.
Zach Urness writes about the outdoors and environment for the Statesman Journal and Register Guard. He’s been reporting on this topic and spoke with KLCC's Rachael McDonald.
Rachael McDonald: Zach, can you tell us why the U.S. Army Corps of Engineers was conducting a drawdown of the reservoir?
Zach Urness: So, to start out, the deep drawdown we're talking about is when the reservoir is emptied to the point where it basically becomes a river. It's a pretty dramatic action and currently there's four Willamette Valley dams where there are deep drawdowns that take place at some point in the year including Green Peter, as you mentioned.
The reason they're doing it is to allow juvenile salmon that are born in the upper rivers above the reservoirs to migrate downstream through openings at the base of the dam and continue on their way to the ocean.
That only works if the reservoir is extremely low. Hence the drawdowns.
The goal here is to restore populations of critically endangered Spring Chinook in the upper Willamette basin. And they're doing that by trying to establish these populations above the dams and reservoirs in this basin. And, you know, it's a process. The adult salmon swim up in the spring, the Army Corps puts them in trucks, takes them around the dam and releases them into the upper rivers where there's better habitat.
And then when the baby salmon are born, they have to migrate back downstream. That's pretty tough if they have to go through a giant reservoir. But it's a lot easier when it's just a river with the drawdowns and that's kind of how it works.
McDonald: What was the issue that nearby cities were experiencing with their water because of the drawdown?
Urness: So in this case, we're really focusing on Green Peter, although there's been similar issues below Lookout Point.
What happens is that when you draw a reservoir down to such a low level, it exposes sediment that's built up since the 1950s and 60s and it just kind of has been there and when that sediment gets flushed downstream during these drawdowns, it creates extremely muddy or turbid water in the South Santiam River. That's a big problem for cities like Sweet Home and Lebanon in particular because that's their water source. And historically, their water source has been remarkably clean. Sweet Home actually won a national award for having the best tasting drinking water.
But when you flush all that sediment into the water supply, it's a problem. It takes a huge wear and tear on their filtration systems. They have to add extra chemicals to keep the water at levels where it's safe to drink.
And, this year, the breaking point happened on November 19 when one of Sweet Home’s water filters basically ruptured because a clot of dirt got stuck in it. There was a fear the town might not be able to deliver safe drinking water if something else went wrong. So, they asked the Army Corps to stop the drawdown process, which means refilling the reservoir. And that's what they're doing. The reservoir is rising and there's less sediment in the river.
McDonald: How will halting the drawdown affect the health of endangered salmon?
Urness: It's hard to say because there's no way of knowing exactly how many juvenile fish made it through the dam before they started refilling it. We do know at least one major pulse of juvenile salmon made it out. But as far as how many didn't, it's hard to know. The drawdown was supposed to last for 30 days, meaning the reservoir was supposed to be basically a river for 30 days. In this case they started refilling it after just 13 days. But what that means for salmon, it's hard to say.
McDonald: I understand from your reporting that the cities actually sued the Corps of Engineers over this. Will that suit go forward?
Urness: Yep, it is still planned to go forward. It should be heard in the next 60 to 90 days. You know, Sweet Home and Lebanon both filed these tort claims against the Army Corps for $37 million basically for repairs and to equip their drinking water systems to handle the sediment from the drawdowns. You know, the cities have said it's not fair for the ratepayers to pay this extra amount of money for the drawdowns that they didn't have anything to do with. And it's been a big issue of local frustration. The drawdown is having this big impact, but the cities haven't gotten any funding to deal with the problem. So, hence the lawsuit.
McDonald: From your reporting, it looks like the Corps was conducting this drawdown because of a previous lawsuit. So, it seems like the Corps is in a difficult position. What’s next?
Urness: So the dams, Green Peter and Lookout Point, it was a lawsuit from three environmental groups that led to the order for the drawdowns. Some things could change next year. You know, some things changed from the previous year, but the plan is for the drawdowns to continue into the future.
There are safeguards like this year built in where the cities can request the drawdown be halted if it's impacting their drinking water supply, but you know, for now the drawdowns are going to continue.
Zach Urness is a reporter for the Statesman Journal and Register Guard. He also hosts the Explore Oregon podcast.
