The Acid Rain Program and Water Quality Monitoring
While many people think of acid rain as an air problem related to air emissions (which it is), acid rain eventually falls to the ground, often ending up in many of our nation’s lakes and streams. Acid rain can cause water bodies to become too acidic, lowering pH to the point where fish and other aquatic organisms can no longer survive. EPA monitors lakes and streams for the impacts of acid rain using two programs: (1) Temporally Integrated Monitoring of Ecosystems (TIME) and (2) Long-Term Monitoring (LTM). These programs have been in existence for over 20 years and the data collected from them has helped researchers at EPA, universities, and several states study trends in water quality to see how lakes and streams are responding to decreases in emissions.
Hard to access, isolated lake and stream sites are sampled in New York, Vermont, Maine, New Hampshire, Pennsylvania, Virginia, and West Virginia. The sites have to be far from cities, roads, and people to make sure that any changes we see in the water quality are not coming from other potential sources of pollution. In some cases, sites are so hard to get to that researchers must use skis or helicopters or hike long distances to reach them. Every year, just as the snow begins to melt, various researchers head out to the sites to start collecting water samples. Since lake samples need to be collected from the deepest part of the lake, researchers generally have to use canoes or inflatable rafts to get to the middle of the lake. Water samples are usually collected several times a year during the spring, summer, and fall. Once at the site, the sample is collected in a bottle and then sent to a lab to be analyzed for sulfate, nitrate, and acid neutralizing capacity (ANC) levels. ANC measures the ability of a system, like a lake, to neutralize or buffer acid. Lakes or streams that have been impacted by acid rain tend to have lower ANC levels and higher levels of sulfate and nitrate. The data from these samples are eventually sent to EPA and posted online so that you can see the sulfate, nitrate, and ANC levels from all of our active sites.
Since the monitoring programs began, we have seen improvements in the water quality at many of the lake and stream sites. This generally means that the water has a higher ANC level than it did when the monitoring began and decreasing nitrate and sulfate concentrations. These trends can be linked to the decreasing SO2 and NOx emissions from power plants under the Acid Rain Program. In some lakes and streams, researchers are now seeing fish that hadn’t been seen in many years due to the low pH levels. However, there are still lakes and streams that have low ANC levels and continue to be impacted by acid rain. EPA continues to monitor all the lake and stream sites in the TIME/LTM programs to see what future changes we might see.
Now that you’ve learned a little more about our water quality monitoring programs in the Acid Rain Program, let’s hear from you. If you’ve ever been involved in lake or stream monitoring in your community, tell us about your experience.
Dani Newcomb works with the TIME/LTM programs in EPA’s Clean Air Markets Division.
Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action, and EPA does not verify the accuracy or science of the contents of the blog.
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