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Its All About Buffers

Clean Water is our Greatest Asset

Clean water, whether it be in a pond, lake, river, estuary, or ocean is one of Maine’s and New Hampshire’s greatest natural assets. As residents, we take for granted its availability for fishing, swimming, boating, drinking, and for just escaping the hectic portions of our daily lives. Yet few of us realize that clean water is not an accident but a process of nature. An endangered and key part of this process are buffers – the vegetated areas (grass, bushes, shrubs, and trees) that surround our streams, rivers, wetlands, and salt marshes.


 Yard debris left on the banks of the rivers and bays can lead to pollution of the water with too much nitrogen, a process called eutrophication. To protect water quality,  don't cut the trees and plants along the banks and don't dump yard debris in these areas.

People are Moving Here

Every year, more and more people are moving into the coastal watersheds of the Greater Piscataqua region of Southern Maine and Seacoast New Hampshire. With them come increases in activities and habits that are putting pressure on our water resources. More roads, more houses, business, and more lawns – built on what had previously been fields, wetlands, and forest.

Increasing Impervious Surface

These landscape changes have one thing in common – the increasing of impervious surfaces (e.g. pavement) and loss of buffer vegetation, where rain instead of soaking into the soil runs off. As stormwater flows off these impervious surfaces it not only retains pollutants from the air but picks up additional pollutants and sediment from roads, roofs, parking lots, bare soil, and lawns. These pollutants are known as non-point source pollution (NPSP).

Stormwater Management is a Challenge

Stormwater containing NPSP is often collected from impervious surfaces in gutters, pipes, drains, ditches and moved as quickly as possible off the site to streams, wetlands, salt marshes, and estuaries – carrying the contaminants with it. If this runoff has little or no contact with vegetation or soil it has no chance to cleanse itself and the pollutants travel directly into the water body.

In water bodies these pollutants can make the water expensive to treat for drinking, unfit for swimming, stimulate algae blooms, kill aquatic organisms including fish, contaminate shellfish, cause salt marshes to “stink”, and in severe cases lower property values and reduce tourism.

high culvert.jpg 

 Stormwater outfalls and culverts such as this one are where the direct impact of our surface waters are felt. 

Impervious surfaces and lack of buffers increases the immediate runoff both in volume and velocity. This occurs as stormwater flows off the land in a much shorter time period increasing peak flows. This accelerates erosion, sediment transport, and severity of flooding while reducing groundwater recharge and later base flows in the same rivers and streams.

We Need Buffers!!!

Vegetated buffers between the built environment and water trap sediments, absorb excess nutrients, neutralize pathogens, prevent erosion, and stabilize sloped areas and the shoreline. Ideally these buffers consist of trees, shrubs, and grasses providing three levels both above and below ground to purify and retain precipitation.

Trees and shrubs intercept raindrops reducing their impact on the soil. Leaf and grass surfaces collect rain and allow for evaporation. Grass and the dead organic “duff” layer on the soil surface filters out sediment and pollutants. Root systems hold soil in place and absorb water and nutrients. Uneven soil surfaces allow rain water and snowmelt to collect and puddle to slowly seep in.

Vegetation also creates shade keeping small brooks and streams cool in summer allowing the water to hold more oxygen – essential for all aquatic life. Water at 40 degrees holds 50% more oxygen as water at 75 degrees. Buffers also accommodate and release flood waters without sustaining lasting damage not to mention providing habitat for birds and animals.

On a parcel by parcel basis the loss of buffers in our coastal watersheds is occurring in insignificant increments. However, due to the increasing number of people living here and the expansion of roads and lawns and the desire for water access and views these insignificant increments are adding up to measurable degradation.

Buffers perform many functions and the minimum widths necessary to perform these functions varies. For example, buffer widths of 50 ft to 100 ft are recommended to prevent adverse water quality impacts to buffered aquatic resources while widths ranging from 95 ft to 330 ft or more may be necessary to maintain wildlife habitat functions depending upon specific species requirements. If multiple functions are targeted, the function with the widest requirement should determine buffer width.

The solution to keeping our water clean is simple, it is all about buffers, their retention, replacement, and enlargement. Once established they require little or no maintenance – and they keep working 24/7 providing what each of us needs and cannot live without.

The Wells National Estuarine Research Reserve at Laudholm Farm, Wells, Maine Copyright 2006 All rights reserved. Collaboration with NOAA CSC, Charleston SC