Rain Gardens ... Chesapeake Bay? 
What's the Connection?

Debby Luquette
Adams County Master Gardener

(1/4) It seems that more and more conversations I have about various types of specialty gardens include rain gardens. And when these discussions arise, they seem to focus on storm water management. Well, using terms like rain garden and storm water management doesn't really excite or interest a lot of people, and many people aren't even sure what this jargon means. These conservations usually are about native plants and handling an abundance of rain water. A rain garden is essentially a garden with native plants designed to collect heavy rains (storm water) and allow it to seep into the ground. When I lived and worked in Maryland, they were ideas that one associated with the Chesapeake Bay watershed more than we do here in Adams County, PA . . . OOPS! Adams County is in the Chesapeake Bay Watershed. It's a fact we often forget, even though most of Adams County is less than two hours away by car.

We don't often associate our land use with the condition of the Chesapeake Bay. I moved to Adams County from Central Maryland where Bay-wise landscaping was more evident. As an environmental educator, I was more attuned to TMDLs, or Total Mean Daily Loads, which is the measure of the main Chesapeake Bay pollutants - nitrogen, phosphate and sediment. It's a 'pollution diet' for the Bay, a means of limiting the amount of this pollution reaching the Bay. As rain water washes over the land, it collects the nitrogen, phosphorous and sediment that eventually reaches the Bay.

In rural Adams County, it seems like a problem that plagues farmers but not the rest of us. This winter, as you drive by fields planted in 'green manure,' grasses and legumes meant to hold soil and nutrients in place during the winter rains and snowmelt, you will realize our farmers are working to limit pollution reaching the Bay. Many farmers are also planting riparian buffers, trees and shrubs planted between field edges and streams to help hold pollutants in place. These wooded edges also attract wildlife and provide a corridor for their movement between fields and farms.

Storm water isn't just a farm problem, though. It can be even more difficult to control in towns and developments. Before this area was settled by European colonists, the land was covered by trees, a fact we acknowledge every time we refer to our state as 'Penn's woods.' The soil that covers our bedrock was thousands of years in the making, and the trees assisted in the process. Rain and snowmelt were held in place by these trees; the water infiltrated the soil and became part of the ground water.

What makes rain water and pollutants an urban and suburban concern? As development increases, so does impervious cover, that is, the surface covered with parking lots, roofs, driveways, stone patios and other surfaces water cannot penetrate. What happens to rain water when the trees are removed in our boroughs and developments? Consider the fact that an inch of rain on an area of impervious cover measuring 1000 square feet yields 623 gallons of water. (from: Rain Garden - The Basics, Lauri Danko, 2017)

Water wants to move down hill and it will carry material with it. The heavier the rainfall, the more water moves downhill, and the more power it has to move pollutants! Look at our lawns and streets and notice what rain water carries to the storm sewers - super-sized drink cups, grit and ice melt, pet waste, fertilizer, oils and lubricants, etc. Water flowing over roads and yards picks up a lot of waste, and storm sewers move this pollution to storm water impoundments or directly into streams.

There are several ways to handle storm water. My answer to this situation is to keep my water on my property. Using rain barrels at gutter downspouts and pervious pavers for the driveway do the job. But I like a Bay-wise rain garden. A rain garden is simply a garden that is located to collect water moving across the ground and designed to allow it to infiltrate the soil. It may take a little construction to shape the ground to hold the water. The plants are usually natives with deep roots and a tolerance for sitting in standing water for a short amount of time. A rain garden becomes a useful and interesting asset to one's landscape, and with native plants they will also support beneficial insects and other wildlife.

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