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New Rain Garden at Cedarmere!

In the fall of 2016 a rain garden was constructed at Cedarmere.

In the fall of 2016 a rain garden was constructed at Cedarmere. A rain garden is a planted basin that allows rainwater runoff from impervious areas, like roofs, driveways, walkways, parking lots, and compacted lawn areas, the opportunity to percolate into the soil. As a result of this filtration process, the amount of sediment and pollutants that would be dumped directly into ponds, harbors and bays is greatly reduced as is the amount of soil erosion. Native plants are planted in the rain garden, and once established, they require little maintenance other than periodic weeding.

Our rain garden was constructed thanks to the Nassau County Soil & Water Conservation District, which has worked closely with the Friends of Cedarmere on various projects involving our pond, trees, invasive plants and the gardens at Cedarmere. The rain garden was funded by the National Fish and Wildlife Foundation as part of a grant that also provided rain gardens at Bayville Village Hall and in Centre Island. All three rain gardens were designed by nationally-recognized expert Rusty Schmidt, a Landscape Ecologist from Nelson, Pope & Voorhis. The Friends of Cedarmere, the Nassau County Soil & Water Conservation District, the Hempstead Harbor Protection Committee, and the Cornell Cooperative Extension Master Gardiners Program all provided volunteers to work on the project. In conjunction with this project, public workshops will be held in 2017 in order to assist homeowners in constructing their own rain gardens.

Our rain garden has turned out to be a perfect solution for runoff problems with our south parking lot which had no provision for drainage. In fact the stormwater was running down the pathway to the bridge and into the pond. This created an ongoing problem of washouts and exposed tree roots in the pathway. The runoff was carrying a sediment load, contributing long-term to the silting up of the pond. Unfiltered runoff adds excess amounts of plant nutrients (nitrogen and phosphorous) and pollutants, primarily from the cars, to the pond water. Our pond is fed predominantly by springs, which carry virtually no sediment into the water. The rain garden should help improve the pond’s water quality and we hope will slow the heavy growth of water plants such as duck weed in summer.

To capture the correct amount of stormwater, the garden is about 600 square feet made of two connected, arched, terraced gardens. The shape and the size were made fit well into the hillside, missing the established trees and shrubs. A line of large natural boulders was installed to hold in place the lower berms of the two basins. To get the stormwater to the raingardens, a French drain was constructed along the entire downslope side of the parking lot to drain all of the stormwater from the parking lot into Raingarden #1. The overflow from this garden goes into a stand pipe drain to Raingarden #2 through a pipe under the pathway that leads to the bridge.

Plants selected for the basins were native damp-woodland species. Woody plants included mountain laurel, witch hazel, bayberry, black chokeberry, black elderberry, highbush blueberry, pagoda dogwood, eastern redbud, flowering dogwood, inkberry, winterberry, and sweetspire. Herbaceous plants were cinnamon fern, Christmas fern, meadowsweet, Solomon’s seal, hardy geranium, white turtlehead, black cohosh, march Saint John’s wort, woodland sunflower, blue sedge, mayapple, jack-in –pulpit, wild columbine.

We also used similar plants to create a 360 square foot woodland garden above the pathway to the parking lot, which book-ends the pathway and creates a gateway into the park.

If you wish to visit Cedarmere to see the rain garden, the grounds are open every day of the year from dawn to dusk. Park in our south parking lot that is about 250 yards south of the main house. As you walk from the parking lot onto the grounds, turn left immediately to follow the pathway that leads down to the stone bridge. The rain garden is on both sides of the path as soon as you start going down the pathway.

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