Published by the American Geological Institute
and Trends in the Geosciences
by Eileen McLellan
In 1970, Ohio’s Cuyahoga River caught fire. The image of a river on fire focused the nation’s attention on the problem of water pollution, and in 1972 the Clean Water Act was passed with the goal of making the nation’s waters “fishable and swimmable.” The Cuyahoga caught fire as a result of the industrial pollutants poured into it. Since 1972, most efforts to clean up rivers and lakes have focused on industry and sewage treatment plants. These are known as “point” sources of pollution because the problem can be traced back to a single point: a pipe discharging into the waterbody. With the Clean Water Act, Congress required point sources to invest in technology to reduce pollution (so-called “end-of-pipe” treatments). The result has been dramatic improvements in the health of many rivers; but we have a long way to go before all rivers are “fishable and swimmable.”
Some waterways have become more, rather than less, polluted over time. This is because we have paid relatively little attention to other sources of pollution collectively known as “nonpoint” sources — urban construction sites, farm fields and forestry operations.
Nonpoint pollution is much harder to manage, because it is spread out over the landscape and it varies depending on site and weather conditions. Controlling nonpoint pollution is less technologically challenging, but more politically challenging, than controlling point pollution. So-called “Best Management Practices,” such as fencing cattle out of streams to prevent erosion of the stream banks and limiting timber harvests, reduce nonpoint pollution considerably but come at a cost for landowners.
Recognizing this cost, and preferring to leave land-use controls to the states, Congress has not required the use of Best Management Practices. In 1987, knowing that landowners would respond better to incentives than to regulation, Congress revised the Clean Water Act to provide grants to states to pay for Best Management Practices. However, funding for this program has always been relatively small compared to the money spent on point sources.
Goals over Means
About five years ago, some enterprising environmental groups discovered a previously unused part of the Clean Water Act., Section 303(d), which takes a totally different approach to cleaning waterways, emphasizing not means but goals. Rather than focusing on how pollution is being reduced through the use of technology and Best Management Practices, it asks whether these reductions are enough to achieve the Clean Water Act’s goal of “fishable and swimmable.”
Recognizing the ambitiousness of balancing “fishable and swimmable” with the needs of an industrial economy, Congress gave the states some flexibility in interpreting section 303(d). Each river or lake in the country has been assigned a designated use, such as recreational, for example. Section 303(d) first requires identifying “impaired” waters in which water quality is inadequate for the designated use. Secondly, it requires determining an acceptable level of pollution that could safely be absorbed by the water without exceeding the standard. This level of pollution is called the Total Maximum Daily Load, or TMDL. Section 303(d) requires that a pollution budget be drawn up that divides the TMDL among all sources in a watershed, point and nonpoint.
Thus, rather than beginning with the source and examining what pollution reductions can be made, section 303(d) takes the reverse approach, starting with the waterbody and determining what pollution reductions are needed. From the scientific perspective, this approach offers several advantages: it provides a scientific underpinning for pollution control efforts by requiring specific linkages between land use, pollution control and water quality; and it recognizes the need to consider the cumulative impacts of all sources in a watershed.
It is, however, politically controversial. Not only does the listing of a waterbody as “impaired” create a stigma, but it also implies that current pollution control efforts are inadequate. In addition, the Environmental Protection Agency (EPA) recently published new rules for enforcing Section 303(d). that make additional pollution reductions mandatory.
A Job for Geologists
Setting water quality goals, such as whether a particular river is to be “fishable and swimmable,” is a policy decision. But the goal must be translated into a water quality standard, a set of numeric criteria for particular pollutants, which means work for biologists and toxicologists. The next step is to determine the TMDL: how much of that pollutant can be added to the river on a daily basis without exceeding the water quality standard. Doing so will require input from chemists, hydrologists and geologists, who must consider how existing pollutants in sediment might affect water quality. Then it must be determined how much pollutant is being added each day on a source-by-source basis. Here again we will rely on geologists to do mass balance studies of sediment and associated chemicals, and to define transfer pathways by which material enters rivers from surface runoff, groundwater flow and atmospheric deposition.
Assuming the amount being added exceeds the TMDL, a policy decision will determine the pollution reductions to be achieved by each source. For nonpoint sources, the next decision is which Best Management Practices will achieve the needed reduction. Much of this is also the work of geologists and hydrologists, who can use field studies and models to determine how effectively a particular Best Management Practice traps sediment or removes nitrogen from groundwater.
Is the state of the science adequate to cope with the inevitable challenges? EPA’s current proposal for implementing section 303(d) will require that scientists quantify the links between land use and water quality, and between Best Management Practices and water quality.
These quantifications will help determine how much pollution reduction a specific landowner must legally achieve.
Can science deliver this level of specificity? The amount of pollution from nonpoint sources is dependent on rainfall; the effectiveness of Best Management Practices in reducing pollution is dependent on site factors such as soil type and slope steepness.
And what are the options when use of our “best” Best Management Practices still does not attain water quality standards? The obvious answer would seem to be to tighten up the Best Management Practice — require that foresters leave wider zones of uncut timber along streambanks, or that suburban areas leave higher percentages of open space undeveloped.
Not only are such efforts likely to meet political challenges, but in some cases they may not fairly address the source of a problem. Some 15 percent of the nitrogen in the Chesapeake Bay is derived from outside the watershed: It is brought in by atmospheric transport from the Midwest. Do we ask landowners in the Chesapeake Bay to carry the burden of reducing this additional load, or do we acquire the political authority to demand reductions elsewhere? What do we do with “legacy” pollutants contributed by past industrial activity, now being released from contaminated sediments, for which there is no current source? What do we when the natural background levels of chemicals in streams exceed the water quality standards, as in some mineralized areas of the West?
Although it offers more questions than answers, the water-quality based approach should not be abandoned. After all, the goal of the Clean Water Act is to make waters “fishable and swimmable,” not to install a certain number of Best Management Practices or end-of-pipe treatments.
The danger with the current proposals comes from an insistence on exact numbers. If we are to hold a landowner legally accountable to numeric standards, we need to be sure that our science is up to it. We will not make progress in cleaning up our rivers if our watershed plans are tied up in court in lawsuits over their scientific adequacy. If we view the TMDL as a broad brush, accept scientific limitations and move forward, we will make progress in cleaning up our rivers. If we insist on exactitude and clearly specified cause-and-effect, we will go down the route of so many toxic tort and Superfund cases — litigation without resolution.
We can make progress if we borrow some of the principles from recent approaches to the Endangered Species Act: flexible science, which takes account of changing circumstances and new information (so-called “adaptive management”), coupled with the use of meaningful landowner incentives. In the end, the challenge may be as much economic as scientific. That is, how to make the use of Best Management Practices and other forms of land stewardship more financially rewarding for landowners.
McLellan is the American Geological Institute's
1999-2000 Congressional Science Fellow and a professor of geology at the
University of Maryland. E-mail: Eileen_McLellan@wyden.senate.gov.