How to build a wetland

MOSES LAKE — Creating a new wetland sometimes starts with moving dirt. Sometimes, it’s a lot of dirt.

“In this situation it does,” said Dave Ryan, owner of Ryan Excavation. “Mainly because what we’re trying to do is get the area that’s going to be the wetland down closer to the elevation of the lake level in summertime.”

There’s still a lot of digging to do on the east end of the new wetland, which is under construction directly adjacent to Interstate 90. It’s part of the construction of the new Love’s Travel Stop, west of Blue Heron Park.

It’s the first wetland for Ryan Construction.

“This is going to go down another six and a half feet to get us down to that (water) level,” Ryan said. “This is the first one. Hopefully not the last. It’s kind of a fun job.”

Building a wetland isn’t particularly complicated.

“It’s fairly simple in that there’s not many steps to it. The main part of this is there’s just an awful lot of dirt,” Ryan said.

Vince Barthels, of T-O Engineers in Spokane, the site’s designer, said the process takes advantage of what’s already there.

“There were some characteristic wetland features,” he said. “In this instance, you have a high water table.”

“Actually, about a third of this (site) is going to be lower than the level of the lake, so it should be wet all summer,” Ryan mentioned.

The first step in building a wetland, Barthels said, is to take inventory

“Basically it starts by doing what’s called a delineation,” he said. That’s a survey to determine what vegetation and landscape features are on the site, and what’s not.

But the site had some unwelcome inhabitants.

“We cleared it first, mainly to get rid of the Russian olive trees. Because they will take over,” Ryan said. “Once we’re done with the dirt, we actually have to spray herbicide and try and kill all the root systems.”

“Trees act as pumps,” Barthels said, and can cause a formerly wet site to dry out. “I’ve seen the inverse happen, too.”

The old landscape will be replaced with cottonwoods and willows, black hawthorn bushes, rushes, even some rabbitbrush. The new wetland will be bigger than the old, and the new design “increases, is probably the best word, the species richness,” Barthels said.

While all the plants are chosen for their suitability for the site, some will get crowded out.

“About 80% of the plants that are installed should make it,” he said.

The site will change as the landscape around it changes. And the expectation of change is built into the design.

“The design is structured so that it can adapt on its own,” he said. “It’s an ecosystem. It kind of adapts with Mother Nature, if you will.”

“I think nature does most of it. We just have to get it close,” Ryan said.

Ryan said the excavation phase should last a couple more weeks.

“I’m hoping by the middle of February, we’ll be done moving dirt. And then we’ll come back in April or May, weather permitting, and we’re going to put in a bunch of topsoil, and plant,” Ryan said. “I’m interested to see how it turns out, once we get it in and everything grows.”

Cheryl Schweizer can be reached via email at cschweizer@columbiabasinherald.com.