EVERETT — The Rev. David Ellingson, a professor at Trinity Lutheran College, said there’s a very direct spiritual connection between Christianity and building a rain garden on the roof of the college’s parking garage.

“In Genesis, I think the first commandment is, ‘Care for the garden, care for creation,’” he said.

Rain gardens use native plants and permeable soils to filter water to remove pollutants and reduce runoff.

The rain garden on the parking garage roof at Wetmore Avenue and California Street is in a planter box about 25 feet long, 4 feet wide and several feet deep.

In 2010, Ellingson helped launch a project to build planter gardens on the roof with trees, flowers and vegetables. There also are children’s play areas and a greenhouse. The college owns the parking garage.

Last year, the rain garden was added to the mix.

The planter box includes native plants such as swamp milkweed and spider plant, and lettuce and other vegetables. As with the other gardens on the roof, the food is harvested and used in the college cafeteria.

The Tulalip Tribes provided a grant to cover the total cost of the garden, which Ellingson estimated at a couple of thousand dollars. Derek Hann of the Snohomish Conservation District provided the expertise.

The water that flows down the slanted surface of one side of the roof is blocked by sandbags and pooled next to a concrete wall. At that spot, a hole was cut in a concrete wall leading into the planter box on the other side of the wall.

On the outside of the planter box a hose is connected to a spigot. From there the water can either be directed to other plants on the roof or discharged into the drain system much cleaner that it was before.

Layers of sand and rocks underneath the soil aid the filtration and drainage process.

“This is a demonstration project,” said Ellingson, a professor of children, youth and family studies. “It’s to show our students, show the community, show the kids they can do this on their own.”

A group of four or five students did much of the physical work, he said. This year, a group of freshmen and sophomores are taking up the mantle of environmental projects.

The Creation Care Club has grown from just a few people in early October to a core group of 15 and total membership of 27, said Elijah Warren, 18.

“We want to expand,” said Kenneth Loth, also 18, looking at the roof. “We want to get this entire rooftop green.”

Bill Sheets: 425-339-3439; sheets@heraldnet.com.