Water Quality Today: Continuously Working Towards Clean Water
Next year will mark the 50th anniversary of the Clean Water Act (CWA) in the United States and while it has had a tremendous impact on our environmental work, it’s important to understand the other factors that define what clean water and water quality means for us today. Under the CWA, the United States Environmental Protection Agency (US EPA) develops and sets national water quality criteria for pollutants and also implements pollution control programs—including wastewater—standards for industry. However, new laws, such as the Safe Drinking Water Act (SWDA), have been passed and implemented over recent decades that provide us with additional clean water regulatory requirements.
The SDWA was passed by Congress in 1974 to provide public health protection through the regulation of public drinking water supplies. Through 1986 and 1996 amendments, SDWA was expanded to protect drinking water sources, including rivers, lakes, reservoirs, springs, and groundwater wells serving more than 25 people. This came about after it was determined that hazards to drinking water may come in the form of naturally-occurring contaminants, improper disposal of chemicals, animal wastes, runoff from agricultural chemicals, wastes disposed of underground, or movement through an improperly-maintained transport system. Today the responsibility for maintaining safe drinking water in our country’s 170,000 public water systems is divided between the EPA, states, tribes, water systems, and the public.
The EPA sets the national standards for drinking water based on state-of-the-science health risks, technology, and costs These standards generally relate to the maximum contaminant levels or requirements for water treatment and are regulated by the level of risk and the likelihood of occurrence in water supply. First a health goal is set based on risk, including risks to the most sensitive populations (i.e., infants, children, pregnant women, and immunocompromised individuals), then a legal limit or treatment requirement is set to be as close to the health goal as possible, with feasibility assessed through cost-benefit analyses. Meeting these SDWA standard requires significant water monitoring, data collection, and analysis and collaboration with state drinking water programs.
The Food Quality Protection Act (FQPA) was enacted in 1996 to set tolerances for the regulation of pesticide residues in food sources. Among other risks, FQPA requires the consideration of aggregate risk from multiple-source exposure to a pesticide, including food, water, residential, or other non-occupational sources. Within 10-years of FQPA’s enactment, the EPA either revoked or modified nearly 4,000 pesticide tolerances.
Enacting CWA, SDWA, and FQPA were important first steps towards clean water. The burden is in implementing the limits set by these Acts, an effort that requires diligent and often large-scale water monitoring programs that incorporate studies designed to effectively collect and analyze samples for quantitative comparison against the current criteria and limits. Today’s analytical technology, including liquid and gas chromatography methods, also play an important role in defining revisions to water limits or monitoring program goals by allowing us to measure lower and lower concentrations of analytes in water. Reducing the laboratory instrument and method detection levels allows us to assess water quality and understand the presence of various compounds in water more confidently.
In addition to water monitoring and analytical developments, environmental modeling plays a critical role in understanding the fate and transport of chemicals in surface and ground water. Exposure models help to simulate the movement of chemicals in water using physical-chemical characteristics of the chemical and representations of the environmental conditions. Geographic Information Systems (GIS) is often used in combination with these models as a link to the watershed data. Groundwater modeling also takes factors such as soil, weather, and chemical properties into account and utilizes specific exposure models as predictive tools.
What we, as scientists, have learned is that the push to lower detection limits must also be considered in terms of the cost-benefit analysis with respect to health goals set forth in regulations. Our job is to seek out the best, most cost-effective path toward meeting these limits that still protects the health of our Earth and its many residents.
To learn more about how to address water quality concerns through monitoring programs and predictive exposure modeling, please contact Jennifer Trask at email@example.com or firstname.lastname@example.org.