The infrastructure of roads, sewers, sidewalks, housing, shopping centers, schools, businesses and parking lots is the template upon which modern society is built and operates. There were few regulations of this design for much of the 20th century beyond ensuring that the abiotic factors of gravity and running water did not flood the streets and neighborhoods of our cities and communities. The infrastructure was designed to carry away the storm water nuisance that would accumulate due to asphalt and concrete transport networks and roofing structures on homes, businesses and public buildings. The developer or state agency such as VDOT had only to create a storm water sewer system that would capture the storm water runoff and carry it to the nearest stream.
The storm sewer system is different from the sanitary sewer system that originates at homes, businesses and public buildings. Waste water from such facilities enters a closed pipe system that transports the water from our kitchens, bathrooms and laundry rooms to a waste water treatment facility, where it receives combined biological and chemical treatment to guarantee that it is clean and free of nutrients and pathogens before re-entering the watershed. This unfortunately is not so for storm water originating from your roof top, sidewalks, roads and parking lots that is flowing through a storm drain in your neighborhood that flows to the nearest creek or stream. That water gets no treatment and unfortunately is laden with a combination of nutrients in the form of fertilizers from lawns and agriculture, pet and litter wastes from streets and and a litany of chemical toxins from road and parking lot surfaces, all of which enter local streams eventually ending up in the Potomac River.
In addition, the imperviousness of our surrounding infrastructure has increased the effect of moving water by increasing the volume of water flow during rain events into our local creeks and streams. The increased volume of water in small stream channels is causing extensive erosion problems that undercuts stream banks and has a destabilizing effect on surrounding trees by loosening and removing the soil surrounding their roots, resulting in their eventual falling into the stream bed and creating blockage to migratory fish species.
Unbridled development in some regions has led to a degree of imperviousness that the volume of water during a rain event overwhelms the capacity for existing storm water infrastructure to carry the water away and flooding results that threatens property.
It was becoming apparent by the end of the 20th century that a different type of threat was weakening the Potomac ecosystem and that in spite of our successful efforts to rein in point source pollution, we had as a consequence of our success in growth and economic expansion of our cities and towns, and the adoption of land-based transport systems created a new non-point source pollution. Recognition of the threat was the first important step. Around the same time, a new science was gaining recognition.
Thomas Lovejoy coined the term biological diversity in 1980, while W. G. Rosen coined the word biodiversity itself in 1985. Adherents to this new discipline believe that as biodiversity disappears, ecosystems become weak and inefficient thereby threatening the health and maintenance of all life. Clearly the Potomac River was imperiled because already in 400 years, the human template on the environment was not only interfering with the abiotic components of the ecosystem, but these interferences were jeopardizing the biodiversity of the ecosystem with the precipitous decline of species like the American shad, Atlantic sturgeon, blue crabs and oysters.
Many feel that the circumstances we are in look grim, and the fact that this problem is an interstate one, involving three different states with their own regulatory bureaucracies, some state and local governing authorities have responded with research and development that have led to a wide range of newly engineered technologies. These engineered systems are beginning to have a positive impact on the Potomac watershed through a pretreatment process for storm water runoff from impervious areas before allowing the water to reenter the watershed.
Next week we'll examine state, county, community and private efforts to remedy the impact of non-point source pollution.