The Harpswell Conservation Commission recently hosted the third installment in a lecture series about understanding and preserving the town’s limited water supply.
This time, landscaping and tree care experts explained how plants can help slow runoff from rainfall, decrease erosion and allow more water to seep into Harpswell’s groundwater reservoir.
The seminar, “The Power of Plants,” was held May 17 at Harpswell Community School. It was preceded by “Fractured Bedrock” in September and “Be Water Wiser” in October. Speakers at the May seminar included landscape designers Jamie Hark and Gavin Boyce-Ratliff.
Harpswell has no “significant aquifer,” a designation for saturated deposits of sand and gravel from which a well can pump water continuously at a rate of 10 gallons per minute or more. Instead, the town sits mostly on outcrops of bedrock that have formed many fractures in which fresh water collects.
Hark, a Conservation Commission member, said residents extract about 275,000 gallons of water from Harpswell’s aquifer each day, with that number doubling to about 550,000 gallons in the summer.
The town receives about 14.5 trillion gallons of precipitation annually, he said, but half of that is lost through runoff and another 30% is lost to “evapotranspiration,” the combined effect of water evaporating from the land and being released by plants as vapor.
Runoff is a significant challenge in Harpswell, which has many thin, steep peninsulas, Hark said. “This is a tricky environment for getting that water available to us with our wells.”
Fast runoff leads to erosion and poor infiltration of water into the soil, he said, whereas slow runoff promotes well recharging and soil and plant health. Proper landscape design can slow or stop runoff, or send it in a desired direction.
Shrubs and trees create friction that slows runoff and promotes soil infiltration and absorption, Hark said. Plants also help filter toxins out of the water, stabilize the soil and reduce evaporation by providing shade.
“(Water) stays on your property, recharges your well and gives you something to drink,” he said.
For sloped properties, Hark recommended planting vegetation at the top and bottom of inclines, and around the home’s perimeter, to help prevent erosion. He said planting seeds, tree whips or live cuttings from local plants can save money and promote faster growth.
Boyce-Ratliff, owner of GBR Landscape Design in Brunswick, described how naturalistic gardens can benefit the surrounding environment. Such gardens emulate natural plant communities and avoid excessive mulching, watering, chemical fertilizers, and pesticides.
“A naturalistic garden might have a lot of ‘ornamental’ plants, but it’s not the same thing as an annual cutting garden or a classic Versailles or Chatsworth,” he said. “We’re going very much on the other end of the spectrum, but we can still use a lot of those plants that you would expect in more traditional gardens.”
Boyce-Ratliff said naturalistic gardens cut down on maintenance requirements and support wildlife and climate resilience while engaging and inspiring property owners. He said the goal is to create as much visual impact as possible with minimal input.
One hurdle is that many property owners still regard dense perennial gardens as messy and unkempt. One way to combat that perception is to maintain a “coherent” mix of plants that go well together and make sense in the local environment, he said.
Another is to keep naturalistic gardens within confined spaces with straight borders, Boyce-Ratliff said. “People have an easier time getting on board with it if it feels like it’s being maintained or controlled on the edges,” he said.
