Stormwater Banking Program
How does development affect water quality?
What is the Stormwater Banking Program?
How can I manage stormwater better at the site, neighborhood, and regional scales?
How does development affect water quality?
According to a 2001 EPA report entitled Our Built and Natural Environment, “Water
quality [in many rivers and streams] is degraded to a point where those water bodies
can no longer support basic uses such as fishing and swimming, and cannot be relied
upon as sources of clean drinking water.” Increasing impervious cover – such as
pavement, rooftops, and other surfaces designed to shed water rapidly – is a major
cause of water quality degradation. Here’s why:
• Impervious cover causes contaminants such as motor oil, heavy metals, fertilizers,
and pet waste to wash directly into streams, resulting in more frequent water quality
problems such as algae blooms and bacterial contamination.
• Impervious cover also increases the volume and rate of stormwater runoff, leading to
larger and more frequent incidents of local flooding.
• Increased flooding leads to physical degradation of streams as floodwaters erode
stream banks.
• All of these impacts lead to increased costs for water treatment, accumulation of
pollutants in our lakes and rivers, and adverse effects on aquatic life in regions where
impervious cover is on the rise.
Conventional stormwater management is designed with a single goal in mind: to
transport stormwater away from where it falls as rapidly and efficiently as possible.
From rooftops to downspouts to gutters to storm drains, a conventional system does a
great job of getting stormwater out of sight, but certainly does not solve the problems.
This becomes more obvious as the number of impaired streams in our region continues
to rise.
Additionally, conventional development has taken the form of sprawl over the past few
decades. According to a recent Growth Study that the Strom Thurmond Institute at
Clemson conducted, since 1990 we in the Upstate have been developing land much
faster than the population has been growing. Specifically, it is occurring five times as
fast. This means that for every 1% increase in population, our amount of developed
land increases by 5%. If these trends continue, over 1.5 million acres will be developed
in the Upstate by 2030 – that’s three times as much as is currently developed!
However, there is still time to avoid this reality. Prior to 1990 we were growing at a
much smaller growth ratio of 0.5:1 ratio – so our population was growing twice as fast
as we were developing land. The change in growth pattern is mostly attributed to an
increase in low-density residential development, and a sharp decline in high-density,
mixed-use developments. Of particular interest is that although Main Street in
Greenville is a very desirable place to live, work, and play – it would be almost
impossible to build under today’s regulations.
Unfortunately, the current approach can be quite costly to the environment – as well as
to the wallet. Many of the problems associated with stormwater, from flooding to
polluted runoff, are directly related to the amount of impervious cover in an area.
Imperviousness in new development has two primary sources: surfaces related to
transportation, mostly streets and parking areas; and roofs of residential, commercial,
and industrial buildings. Of the two, transportation-related infrastructure accounts for
the majority of new impervious cover. According to the Center for Watershed
Protection, streets, parking lots, and other “habitat for cars” account for between 60%
and 70% of impervious cover being built in the United States today. In addition, parking
lots and roads are often built far larger than necessary. Conventional stormwater
systems in a sense exacerbate the problem, as every part of a conventional system but
the detention basin is itself impervious. To top it off, concrete is expensive to build and
maintain, so all this impervious cover can put a real dent in the bottom line.
What is the Stormwater Banking Program?
In partnership with Greenville County and Clemson University, and with support from
the EPA, we are working to develop a Stormwater Banking Program (SBP). The goal of
the SBP is to improve water quality by creating a market-driven system that (1)
incentivizes development that is more benign to water quality on a site, neighborhood,
and regional scale, and (2) generates funds to complete stormwater retrofits throughout
Greenville County.
As a part of the SBP, we are developing a Decision-Making Tool (DMT) that will
estimate water quality impacts on a site, neighborhood, and regional scale. The DMT
will serve as the scoring mechanism for the SBP and will be used by developers and
engineers as an evaluative tool as they are planning the layout, design, and stormwater
management on their development site. In addition, using the tool will help educate
developers about development characteristics that can be implemented to lessen their
impact on water quality at numerous scales.
How can I manage stormwater better at the site, neighborhood, and regional
scales?
Stormwater management must be considered on a site, neighborhood, and regional
scale to be truly effective. Most stormwater management education and research in the
past has been focused only on site-scale best management practices. Recently, the
EPA said that we will not meet the goals of the Clean Water Act by focusing on sitelevel strategies alone. Rather, we must also focus on the way we are connecting our
neighborhoods, how well they are set up for multi-modal transportation, and where we
are developing in relation to urban and town centers to actually meet our water quality
goals.
Click here to find out more about Site-Scale Solutions, Neighborhood-Scale
Solutions, and Regional Solutions.
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