By: David A. Bainbridge
Solving a problem often depends on how you define it. Stormwater is a perfect example. The conversion of natural areas to urban and suburban uses results in many changes to ecosystem function. Two of the most visible impacts are water pollution from materials picked up in stormwater flows after rainstorms and changes in the hydrologic (water) cycle as impervious surfaces increase. This results in more common and severe flooding as the 100 year flood becomes a ten year flood. Rainwater and runoff flush pollutants into creeks, streams, and the ocean.
You wouldn’t want to drink it! Common contaminants in stormwater runoff include bacteria, viruses, fertilizers, detergents, antifreeze, herbicides, pesticides, pet feces, drugs, and ecotoxic metals (copper, lead, cadmium, zinc). Nitrogen pollution from atmospheric deposition of contaminants from fossil fuels combustion is a critical yet little recognized problem in stormwater runoff. And fertilizers add phosphorus and nitrogen to sensitive waterways.
Stormwater management is in most cases a municipal concern as a result of mandates from the Environmental Protection Agency. These mandates are passed down from state regulatory agencies to cities and counties. Very few areas in the United States have developed effective stormwater-management programs, because they have ignored the economic costs.
Increased erosion and sediment deposition are the most obvious. Studies done by Luna Leopold and M.G. Wolman in the 1960s found that construction sites can generate 40,000 times as much sediment as natural areas. The increased sediment causes many problems that entail high costs, including blocked drains and bridges that increase flooding, damaged ecosystems, and destabilized aquatic ecosystems caused by added nutrients to streams and waterways. Most construction stormwater management plans are ineffectual at best as erosion control features are incorrectly installed or incomplete.
Stormwater related pollution is responsible for most of the 1,000 or more beach closures each year in California. This may sound bad, but the number of closures is actually a good sign because it shows more monitoring is being done. In many states, a swimmer assumes a risk each time he or she enters the water. As a result of a growing recognition of the stormwater problem in California, regular, but still limited, monitoring is now done. A toxicity survey in 1997 found that all San Diego stormwater samples tested with a bioassay were biotoxic, even though they rarely exceeded standards for key pollutants.
Stormwater pollution is neglected by enforcement agencies because it is seen as a victimless crime. However, it results in many costs to individuals, society, government agencies, taxpayers, and other sectors of the economy. These costs include repair to bridges, roads, dams and parks, loss in tourism revenue, costs for medical treatment and health care, lost productivity, and damage to aquatic resources leading to lost tourist revenue. Costs to ecosystems are harder to quantify, but proxy costs may be estimated, such as the cost to avoid pollution or the cost to restore damaged creeks and aquatic ecosystems. A recent study in San Diego suggested that the government recovers only 14% of the direct cost of stormwater, if we include external costs it may be 5% or even just 1%.
Stormwater pollution is generally understood and the focus of most stormwater campaigns (Don’t pour motor oil in the creek!); but urbanization causes local, severe changes in the hydrologic cycle. Streets, parking lots, driveways, sidewalks, and roofs dramatically increase the percentage of soil surface that is impervious to water. This may be 50% in residential areas and 90% in commercial and industrial areas. Rain can’t make its way into the soil and instead runs off quickly into streams, causing much more rapid, frequent and larger peak floods. These high flood flows further destabilize streambeds, mobilizing more sediment that in turn can destabilize lower stream reaches and cause cascading problems. Flooding from a major rainfall event can be catastrophic, reaching far beyond the 100-year flood plains identified before urbanization took place.
Discussion of impervious surfaces in the planning community has gradually increased, but the true costs have been neglected. The fundamental problems have remained largely untouched, even though they were first clearly described almost 40 years ago. Although anyone flooded out by upstream development should be able to hold the city or county or upstream developers accountable when the cause is urbanization, this flooding is seen as an “act of God.”
True cost accounting can reduce stormwater pollution and runoff. Charging impact fees in relation to runoff water quantity and quality will limit flooding and stormwater pollution. Stormwater impact fees can also support educational programs to help landowners understand how to restrict stormwater runoff and reduce their fees. Fort Collins, Colorado has one of the most comprehensive fee systems, tailored to individual drainage basins. Fees for common contaminants found in stormwater can help fund private, city, and county recycling and recovery programs. They would also pay for increased street sweeping and regular creek cleanups. And they could compensate hospitals and clinics for costs associated with treating people who became ill as a result of contact with contaminated stormwater.
Development standards should require no net increase in stormwater runoff. This is not hard, but may require infiltration control structures (gravel-filled trenches, detention basins, retention swales, tanks, roof gutters and rainwater harvesting cisterns and tanks, chambers, ponds); porous pavement for some roads, parking lots, and walkways; and other runoff-limiting strategies. Roughing filters and biofilters can be used to capture pollutants before they enter waterways.
Development guidelines that minimize impervious surfaces and encourage aboveground water collection and retention will be adopted if stormwater costs are charged. Narrower streets are desirable, as is cluster housing rather than a conventional grid layout. Changing road widths and lot design and moving to aboveground drainage in the Village Homes development (200+ units and commercial space) in Davis, California, saved money and reduced impervious surfaces and runoff. Although the city engineers fought these features, the development performed very well and did not flood while most areas of the city did in a major storm. Future developments found it much easier to adopt stormwater management activities. A developer in San Diego told me that he saved $1 million by moving from a stormwater pipe solution to aboveground drains, swales, and basins in one development.
Landowners and stormwater polluters should be given the choice of minimizing off-site impacts or paying the financial burden they place on communities. The market for this must be established and this would entail some cost; however, ultimately it should operate at no cost to the public and will result in substantial savings. A fee-based stormwater market solution should result in tax reductions and creation of a number of new business opportunities.
It is relatively easy to charge fees for both stormwater pollutants and stormwater runoff. For the pollutants found in stormwater, a pollution charge should be added at point of sale for non-recyclables and a deposit fee should be instituted for recyclable materials such as motor oil. Implementation of these fees should be prioritized by local stormwater pollutant loads found in stormwater monitoring. A percent of the gas tax should be redirected to the stormwater services program to account for nitrogen impacts.
Runoff can be limited by charging a fee for each square foot of impervious surface without control treatment. If stormwater retention facilities, infiltration beds, chambers, and other treatment options are installed, then the charge should be reduced or eliminated. Seattle, Denver and other cities have adopted modest impact fees. Some districts are using Googleearth to estimate or check impervious surface percentages. Government agencies should not be immune to fee requirements.
Stormwater should be seen as a resource not a waste. It is free salt-free rainwater delivered to each home. Yet in most areas the water supply agencies have no interest or commitment to rainwater capture, even in areas that are desperate for water. In San Diego I participated in a water supply design effort where the water agency explicitly refused to consider rainwater. If true costs were paid for water and stormwater these agencies would be working closely together. And homeowners and business would be installing rainwater collection and storage systems.
Stormwater management can provide many economic benefits, including reduced flood damage, lower health costs, and the protection of recreational activities, tourism, and commercial and recreational fisheries. It also provides many ecological benefits such as protecting the health of ecosystems and preserving critical biodiversity. Using financial incentives that focus on performance rather than prescriptive regulations can encourage innovation, speed adoption, and eliminate costs to the taxpayer. By placing fiscal responsibility for stormwater problems where it belongs, rather than on taxpayers or future generations, communities, the economy, and natural ecosystems can remain healthy and productive.
Adapted from “Rebuilding the American Economy” free download at www.sustainabilityleader.org
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