Posted: July 13, 2020

A single home containing 2,000 square feet of external impervious surface can produce 1,246 gallons of stormwater runoff in a typical rainstorm. When we see this downpour racing off house roofs, overflowing from roof gutters, and rapidly traversing driveways, lawns, and walkways, have we ever considered where it goes and what damage it might be doing along the way?

Runoff can cause significant flooding in small creeks

Runoff can cause significant flooding in small creeks

On residential properties, stormwater and the pollutants it gathers on its journey can cause structural damage to both homes and their surroundings. Basements can be flooded, house foundations and septic systems can be damaged, and lawns and driveways can be washed out. Stormwater runoff also can contaminate wells and nearby springs, ultimately reducing water quality and diminishing well capacity and spring flows.

For townships, the consequences of stormwater damage can be quite significant. The recent experience of Shrewsbury Township illustrates how costly the damage from unmanaged or uncontrolled stormwater can be. Shrewsbury Township is a 29-square mile, rural-agricultural municipality located in York County, PA and has a 2010 population of 6,447 residents. Over Labor Day weekend, 2018, the township was devastated by a series of tropical-like rainstorms. Repairing the damage to public infrastructure alone (e.g., road surfaces, road shoulders, bridges, culverts, guiderails, parks, and stormwater management structures) from these rainstorms is expected to cost $1.3 million dollars over the next 2-1/2 years. The 2,536 households who make up this township will be among those taxpayers who must bear this substantial cost. No estimate is available of the cost to repair the damage to private properties, which most certainly will exceed the public cost.

Polluted runoff has adverse effects on the region's water related resources as well. Runoff typically proceeds from its local receiving stream to the Susquehanna River, then to the Chesapeake Bay, and finally into the Atlantic Ocean. The Susquehanna River, which is the source of one-half of the Bay's freshwater, is degraded from both runoff and the numerous sewage and wastewater treatment plants that dot its banks.

The Chesapeake Bay itself, once the most productive estuary in the world, is seriously degraded. The oyster population, which once flourished in the Bay and plays a key role in filtration of the Bay's water, has declined to 1% of historical levels. (Oysters are important to water quality because a single adult oyster can filter 50 gallons of Bay water daily.) Historically, the flourishing oyster population was able to filter the entire Bay in just one week; it would take the current oyster population more than a year. An unhealthy Chesapeake Bay adversely impacts the economy of the region, the fish and shellfish we all love to eat, and the quality and character of places in which many Pennsylvania residents spend time for recreation. In particular, a productive Bay sustains the Bay's watermen, the "farmers" of the Bay's bounty.

This stormwater is part of the hydrologic cycle, which is the movement and recycling of water in the environment. All precipitation, including rainwater, originates from water on the Earth's surface. When precipitation occurs, some of the water evaporates and returns to the atmosphere due to the efforts of the sun, or to plants, which draw water into their leaves along with needed nutrients. Some precipitation penetrates the soil, entering seeps, springs, rivers, and streams and recharging groundwater. Precipitation that evaporates or that is able to infiltrate slowly into the ground benefits from a natural filtration process by which impurities are removed. Precipitation that does not evaporate or seep slowly into the earth becomes runoff. The amount of water on this earth is constant, or never changing. Today, we are consuming the very same, albeit naturally recycled, water as was consumed by our predecessors.

Rivers and streams that are observed to be muddy following rainstorms provide highly visible evidence that our stormwater management practices are less than ideal. In Pennsylvania, there are over 12,200 miles of streams that have been polluted, as well as over 3,000 miles of streams that have been impaired, by stormwater runoff.

While many land uses - whether commercial, industrial, institutional, or agricultural - contribute to runoff, the cumulative impact from hundreds of thousands of residential parcels can be enormous. Civically, and, some would claim, morally, property owners have responsibility for the rainfall and other forms of precipitation that collect on their land.

However, with the responsibility for water stewardship comes opportunity. The water that falls on a property defacto belongs to the property owner. Property owners who increase their awareness of stormwater and develop plans to manage it can gain direct benefits from this resource. If retained and managed on-site, stormwater can contribute to water quality and supply and enhance the aesthetics of a property, increasing its value and the property owner's quality of life.

What are property owners to do? They should begin by observing the degree, characteristics, and flow pattern of runoff on their lots during a number of storm events. The next step is to eliminate the sources of pollutants that are likely to be washed off the parcel. The property owner can then begin to implement best management practices on their parcel, such as the following:

  • Direct all downspouts or roof runoff to underground infiltration pits or structures, or, alternatively, to rain gardens or retention pools.
  • Eliminate or reduce the area in lawns. Instead, plant native wildflowers or native warm season grasses, which do not require mowing, and which benefit pollinators such as butterflies and hummingbirds as well as songbirds and other wildlife.
  • Plant native trees, shrubs, and ground cover, which soak up to fourteen times more rainwater than grass lawns.
  • Redirect runoff from driveways, patios, sidewalks, and other impervious surfaces to adjacent or on-lot woodlands, fields, and other pervious surfaces or areas such as rain gardens and depressed areas. These can serve as effective temporary infiltration structures during rain events. Every square foot of impervious surface generates two gallons of runoff during a typical rainfall.
  • Install pervious surfaces rather than impervious surfaces for driveways, walks, etc. Utilize effective/longlasting pervious surfaces, such as wood decks, bricks, and concrete lattice, where feasible.
  • Avoid composting yard waste such as leaves, grass clippings, or mulch into or near a stream or stormwater drain. Install rain barrels, particularly on small lots.
  • Install buffer strips containing thick vegetation or berms that promote infiltration, thereby reducing runoff.
  • Never wash vehicles on impervious surfaces such as parking pads or driveways, unless all waste water will be infiltrated on-site. Rather, utilize porous surfaces or, ideally, a local car wash facility.

By incorporating these and other practices, property owners can create healthier, safer, and more attractive living environments for themselves as well as for everyone in their community and across the region.

Weather forecasters continue to predict an increase in both the volume and intensity of storm events due primarily to climate change, specifically, the warming of the Earth's atmosphere. As a result, damage to both public and private properties from uncontrolled stormwater will continue to increase. The choice facing local governments and property owners alike is whether to proactively manage stormwater flows or to continue to pay the high cost of damage from uncontrolled stormwater. Which path will we choose?

Paul J. Solomon is a retired Shrewsbury Township Supervisor in York County, PA, a private forest landowner, and a Pennsylvania Forest Steward and Master Watershed Steward volunteer. He resides in New Freedom, PA.

Center for Private Forests

Address

416 Forest Resources Building
University Park, PA 16802

Center for Private Forests

Address

416 Forest Resources Building
University Park, PA 16802