It rains a lot on the North Coast. Which, yes, is kind of like saying sometimes fish swim and most birds fly and people are born when they’re babies.
But the Lewis and Clark National Historical Park (Fort Clatsop) is planning for the rain, and resulting water run-off, in a new way.
Construction on a rain garden outside of the visitor’s center began on Valentine’s Day. Along with Robyn McGlade and Colby Weathers of the Manzanita-based Native Landscape Design, LLC, park staff began plowing the patch of land.
Rain gardens are designed to absorb and clean up excessive run-off water (stormwater) from hard surfaces like parking lots, sidewalks, streets and roofs.
Stormwater can be dirty stuff, carrying heavy metals, pollutants, bacteria, trash, pesticides, oil and grease along with it as it sluices down a drain pipe or streams across a street.
The park, with its multiple buildings, sees a lot of run-off.
This run-off is a “sudden impact,” on aquatic life and habitats, a sort of flash flood, said Robert Emanuel, water resources and community development educator with Oregon State University Sea Grant Extension in Tillamook County. He is working with the park to develop the rain garden and other water resources projects.
Run-off from parking lots can be especially damaging, Emanuel said.
“We find a lot of copper in auto-dominated areas,” he said, and copper is bad news for salmon. It can affect their ability to detect predators and can even lead to pre-spawning deaths.
“The more hard surfaces you put on a landscape, the more impact there is,” he said.
For the park, a rain garden seemed like a simple solution.
The sunken landscape of a rain garden captures the stormwater and lets it soak into the ground to be used by plants. Soil microorganisms and plant roots help break down the pollutants.
“When we started thinking about doing this there were multiple goals,” said Carla Cole, natural resources project manager at the park. “We wanted better stormwater management, but this is also a high-visibility spot. We can show visitors how to do this kind of garden and what it might look like.”
In addition to being a demonstration for how a rain garden functions, the park’s garden is designed to look like a watershed in miniature, McGlade and Weathers said, and will hopefully illustrate what they call “the edge,” a delicate, bio-diverse spot where different systems meet: forest and meadow, land and stream, for example.
It will also be a lesson in history.
As visitors walk down the sidewalk that runs between the parking lot and the rain garden site, they’ll see a historic sort of path unfold next to them, as if they were traveling with Lewis and Clark. Agricultural land (with its own specific plants) will slowly turn into the wetter, forest and slough land of the Pacific Northwest, ending at the rain garden.
Portions of the garden will even be bordered with river rock from the Missoula Floods, another history lesson. Thousands of years ago, when massive floods swept from Montana through Washington and carved out the Columbia River Gorge, the waters carried rock with them.
Some of this Montana granite has been found in the national park and Weathers said about one third of the rock they’re using in the rain garden was harvested on park property.
“So we’re also stepping back in geologic time,” he said.
For Emanuel, when rain gardens make sense at a site, they make a lot of sense.
“I don’t think they’ll ever really take off in Astoria,” he said. The art of building rain gardens is to look at and understand the land, he said. Astoria is too steep and prone to slides.
“You have to pay attention to your topography and safety,” he said. “You don’t want to send water to your foundation or your basement.” Or, for that matter, to other people’s foundations or basements.
But Emanuel sees rain gardens as perfect options for cities like Warrenton, Seaside or Cannon Beach.
“You want to do this where it’s safe,” he said. “If you have the opportunity, you should take advantage of it.”
Stormwater is not highly regulated in small communities like it is in Portland, he said, but it can still generate impacts.
The park’s rain garden may not look like much yet – a channel sketched out and marked by yellow flags, piles of soil, and people walking around in muddy boots while the wind gusts and the rain falls – but give them some time.
Excavation work will continue all this week. Emanuel says the plan is to let the garden sit for a few days and then, on Feb.22, the OSU Master Gardners, park employees and others will plant the garden.