Stormwater Issues & Solutions
What is the problem?
Over time, people have changed the landscape of the Chesapeake Bay watershed. Hard coverings such as paved roads and parking lots, roofs and other impervious surfaces have replaced what were once open fields and forests. According to the Chesapeake Bay Program, between 1990 and 2000 the population in the Chesapeake Bay watershed increased eight percent, yet the amount of impervious surface increased 41 percent.
Before extensive development, the landscape absorbed much of the rainfall. This natural process filters out pollutants, recharges groundwater, and reduces the likelihood of erosion and flooding. In urban and suburban settings, rainfall washes over impervious surfaces creating runoff. Downspouts, hard surfaces, and storm drains are used to divert and channel stormwater runoff directly into local waterways and the Chesapeake Bay. Rainfall that washes over impervious surfaces picks up a wide range of pollutants including fertilizers, pesticides, oils, metals, and sediment.
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Parking areas, streets and rooftops are impervious surfaces (loosely defined as areas where water cannot penetrate the ground). Even a lush lawn growing on compacted soil can be considered an impervious surface.
Traditional drainage systems concentrate runoff from these surfaces and remove it as quickly as possible by a system of gutters, curbs, pipes, sewers, and channels. The result is large amounts of fast-moving and sometimes highly polluted water discharging into local rivers, causing erosion, flooding, and unstable stream channels. Pollutants can include litter, pet waste, vehicle fluids, and fertilizers and pesticides applied to lawns.
Studies show that significant impairment of waterways often occurs when just 10% of the land in the watershed is covered with parking lots and rooftops. However, if these areas exceed 25% of the land, severe ecosystem and water quality impairment occurs.
Source: Chesapeake Bay Program
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Beautiful Solutions to Water Pollution
Alternatives to Impervious Surfaces
• Reduce/Rethink Lawns
Although lawns can prevent erosion better than bare soil, most other types of landscape plantings provide more benefits to the environment than does a lawn. Many lawns have become very compacted, too full of toxic chemicals, and a drain on our time, energy, and financial resources. They can be almost as bad as impervious surfaces in causing rapid runoff. For example, a thick, green lawn can be [be largely] impervious according to the U.S. Environmental Protection Agency.
In most cities and suburbs, lawns are the most prominent type of vegetation. Lawns are also the most resource-consuming, as well as polluting form of landscaping…. Reducing the size of lawns and using common sense to maintain them will reduce the quantity of water and other inputs needed.
Source: Chesapeake Bay Program
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• Natural Resource Preservation and Conservation Landscaping
Preserving the natural landscape and resources can improve the marketability of a community and homes within it. Existing wooded areas, mature trees, and natural terrain provide an attractive appearance and recreational amenities. Landscaping with plants native to the Bay region's climate and soil conditions (conservation landscaping), requires less water, fertilizer, pesticides and maintenance than non-native plant varieties in ornamental gardens.
• Grass Swales and Filter Strips
Swales are an alternative to the curb and gutter system. Grasses or other low-growing vegetation are planted to reduce runoff velocity and allow filtration, while high volume flows are channeled away safely. Native plant species such as white ash, red cedar, arrow wood viburnum, chokeberry, sunflowers and switchgrass could be planted in these swales due to their tolerance of salt spray and snow compaction in the winter months.
Filter Strips are landscape features designed within parking lots to collect runoff from the large impervious surfaces. They may direct water into specially designed vegetated detention areas or underground sand filters that capture pollutants and gradually release water over a period of time.
• Decks, Patios and Pathways
These areas can be constructed with pervious materials that allow water to be absorbed into the ground. Wood, stone, cobble, loosely laid brick and paving blocks are some of the materials that can be used in the outdoor landscape. Heavily traveled lawn areas may become impervious if the soil underneath has become compacted by heavy machinery or foot traffic. Because soil compaction is difficult and expensive to correct, the emphasis is on prevention. Pathways made of uncomposted hardwood mulch (obtainable from a tree company) can be used to keep traffic in one area. Paving blocks made with cement or plastic are not recommended for high traffic areas for durability reasons. For patios and path ways, depending on the soil type and infiltration rate, a gravel layer may be needed underneath the materials to prevent settling and to allow further infiltration.
The Benefits of Trees
According to the American Forestry Association, a single urban tree provides a benefit of $273 per year. Trees provide many benefits: energy savings by reducing heating and cooling costs; sheltering and feeding wildlife; cleansing the air by absorption of carbon dioxide and nutrients; and reduction of the impacts of stormwater runoff by intercepting rainfall and slowing runoff. The roots of a tree also help to hold the soil in place thus reducing erosion.
Source: Alliance for the Chesapeake Bay
According to Professor Doug Tallamy, University of Delaware, "Native plants sustain native pollinators and other beneficial wildlife, compared to non-native plants which often provide poor habitat. For instance, one native oak tree can provide habitat for over 500 butterfly and moth species! An exotic species like a Bradford pear, by contrast, might provide habitat for one or two species." Notably, 75 percent of food crops require fertilization by animal pollinators in order to produce fruit and seed.
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What solution should I use?
Actually, there are many solutions. Rainscaping practices integrate a variety of methods to reduce the impact of polluted runoff. Most of the practices described are approaches you can implement in your own front and backyard. Other practices may require professional help.
RainScaping incorporates general conservation landscaping practices, including using native plants, removing invasive plants,conserving water, eliminating or reducing chemical fertilizers and pesticides to reduce pollution and conserve resources, shaping the ground for better infiltration and to control erosion, and enhancing aesthetics and wildlife habitat.
Help spread the word about RainScaping in your neighborhood!
Incentives for Stormwater Runoff Solutions
***Anne Arundel County property owners who install rain barrels, rain gardens or other stormwater controls are eligible for a property-tax credit equal to 10 percent of the cost of the improvement, for five years. The deduction is capped at $10,000 over the five years. Homeowners will receive a 10 percent credit for each of the five years, for 50 percent total.***
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