SPOTLIGHT: Why Boise Is Opening A Water Treatment Plant In Another County

Aug 24, 2016

The City of Boise is holding a celebration today for the opening of a new public works facility. But the facility isn’t in Boise. In fact, it’s a county away. And it’s meant to do something cities don’t normally do: Clean water polluted by agriculture. It’s called the Dixie Drain project and KBSX's Adam Cotterell has reported on it in the past. Adam told Scott Graf what the Dixie Drain project is.

Adam Cotterell: So you can think of a drain as the opposite of an irrigation canal. They’re dug to take excess water from farm fields to the river. Dixie Drain snakes its way through Canyon County farms and then empties into the Boise River not far from where the Boise empties into the Snake River near Notus. The project is a water purification plant. It pumps water out of the drain, removes the phosphorous and pumps the water back into the drain.

Scott Graf: Why is it necessary to take phosphorous out of the water?

Phosphorous is great for plants. In the case of Dixie Drain, it’s coming from fertilizer and manure. But if too much of it gets into rivers, it can make water plants grow like crazy. That sucks the oxygen out of the water and can kill the fish. It’s a big concern in the lower Snake River.

There’s not a lot of farming in Boise. So why is the city doing this for farms in Canyon County?

Basically, so Boise doesn’t have to remove phosphorous from its sewage. See, this whole thing goes back more than seven years. Boise waste managers knew the EPA planned to start regulating how much phosphorous cities could dump into rivers. They also knew it would be expensive to comply with those regulations. So they came up with an idea that turned out to be pretty innovative. They’d go somewhere else and prevent more phosphorous from getting to the river for less money.

How does building a brand new treatment plant save money?

Boise Public Works managers say that for fairly little money they could have gone from removing no phosphorous at the Boise sewage treatment plant to removing 93 or 94 percent of it. But the EPA regulations turned out to say the city had to remove 98 percent. And the technology and the energy to get that last 4 or 5 percent was really expensive. City engineers crunched the numbers and said it would be cheaper to build a new plant somewhere else. So they took that idea to the EPA.

How did that particular federal agency react?

At first EPA officials were really skeptical. After all, the city was essentially saying, ‘Hey you know those new rules you’re working on? We’d like your blessing to break them.’"

But they came around?

It took some convincing but now the agency is all in. Some of its top leaders have called Dixie Drain one of the most innovative solutions they’ve seen in a long time. One of the reasons is that agriculture puts way more phosphorous into rivers than cities, but the EPA doesn’t have the authority to tell farmers to clean it up. So it tries to solve the problem other ways like really tough regulations on cities. So Boise was saying, 'If you ease up on us we’ll go tackle the problem where it’s worse but where you can’t go.’"

So what was the final deal?

Boise still has to remove 94 percent of the phosphorous going into the river at its sewage plants. And for every pound it doesn’t remove there it will remove a pound and a half from Dixie Drain.

How has this project been received by people outside government circles?

Pretty well. The Idaho Conservation League likes it a lot. There were some critics who didn’t like the idea of a city being allowed to get out of environmental regulations and others who point out that even with the new plant, Dixie Drain will still be putting a lot of phosphorous into the river so maybe Boise should be taking more out. And there were budget hawks who were skeptical about the claim that it would actually end up being cheaper than just doing the upgrades to the sewage plant.

Now that it’s been built was it cheaper?

The city says yes. I asked for the final price tag this week. A spokesman for the mayor says it cost about $21 million to build. He says that’s cheaper than what it would have cost to do the upgrades. But when you extend it out 20 years what with the operating costs for the facility it comes out about the same.

Is this pollution offsetting something we’re likely to see more of?

Maybe. The EPA says no city has ever done anything quite like Dixie Drain. And - reportedly - a lot of people in city governments around the country have been watching Boise closely for the last few years to see how much this would end up costing. So we certainly may see more projects like this in the future.

The city’s opening celebration for the Dixie Drain project is planned for Wednesday morning and features Boise mayor Dave Bieter, Congressman Mike Simpson and representatives from the EPA and the Idaho Department of Environmental Quality. ​

Find Adam Cotterell on Twitter @cotterelladam

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