Back to Nature: Take Part in a Study of Virginia’s Native Trout Streams

Ami Riscassi, a UVA senior research scientist, will coordinate the collection of hundreds of water samples this spring to help assess the health of the state’s native trout habitats.
Ami Riscassi, a UVA senior research scientist, will coordinate the collection of hundreds of water samples this spring to help assess the health of the state’s native trout habitats.
Dan Addison / University Communications

Just over 30 years after Congress enacted the last major changes to the Clean Air Act, the federal law aimed at protecting and improving the nation’s air quality, researchers with the University of Virginia’s Department of Environmental Sciences and volunteers across Virginia are preparing to embark on the next phase of a study designed to determine just how effective those laws have been at protecting one of the commonwealth’s natural resources.

Every quarter of every year since 1987, the Shenandoah Watershed Study and the Virginia Trout Stream Sensitivity Study monitor a subset of the trout streams in the commonwealth’s western mountains, predominantly in national forest and national park lands, to evaluate the effects of acid deposition (also known as acid rain) and other factors affecting water quality of Virginia’s native trout streams.

Every decade, the studies undertake a more comprehensive survey of the state’s mountain streams. This April 24 to 30, with the help of Trout Unlimited, a nonprofit organization dedicated to the conservation of freshwater streams, rivers and habitats for trout and other aquatic species, the watershed and trout stream studies will collect hundreds of water samples that natural resource management agencies and policymakers will use to understand the impact of clean air legislation and the health of resources that are affected by those laws.

Ami Riscassi, senior research scientist and project coordinator for both studies, spoke with UVA Today to explain the importance this year’s survey and the role its volunteers will play.

Q. What’s the goal of this year’s survey?

A. I would say the goal is twofold.

First, we’re looking to gain insight into how stream chemistry has changed since 1987 in the vast majority of streams that sustain a native brook trout population in Virginia, and then we use that information to determine whether the trends we observe at the subset of sites we sample each year are, in fact, representative of what is going on in the entire region.


The survey will provide the National Park Service, the U.S. Forest Service, the Virginia Department of Wildlife Resources and the EPA comprehensive information about the suitability of the streams from a water quality standpoint.

Second, I think it’s important to connect with the fishing community, to provide them with information about the conditions of their trout streams and what we, as scientists, are doing to make sure we understand the threats to this valuable resource moving forward. They’re great to talk to and work with. They’re so knowledgeable about their local streams, and their love of and concern for the rivers and the fish provides us with an important perspective. I believe having that communication between the scientists and the users of the resource is really important for both of us.

Q. What changes have you seen in Virginia’s streams since the study started?

A. Acid deposition, in particular sulfur deposition, which is the main acidifier in mountain streams, has decreased by between 80% and 90% since the Clean Air Act Amendments of 1990, which is great!

When we look at the trends in Virginia over the same period, however, the rates of decrease are much smaller. The difference is that the soils in our region retain sulfur, so the acidity is, in essence, slowly ‘leaking’ back out. We’ve also seen that there’s a wide range of rates of recovery in our region, and that has to do with the bedrock. Different types of bedrock are better at neutralizing acids. The streams that were least acidified are improving faster than the streams that were most acidified; that’s what our data have been telling us so far.

Q. What part will the 2021 regional survey play in the study overall?

A. The important thing about this data set is that it gains importance with every decade. The first year you do a survey, you’re just trying to understand what the status is. The second year you’ve got two data points in time, and by the third year you’re starting to get a little bit more information. This being the fourth year, we’re really hoping to bring in some statistical power to evaluate the trends we see emerging and how that compares to our understanding of what’s happening in the subset of sites that we sample more regularly.

And with climate change, there are new threats, especially in cold-water brook trout streams, so understanding the legacy of acidification and the compounding effects of changing temperatures will play an important role in helping us understand the future habitat for these important species.

Q. How will this study contribute to the future health of Virginia’s streams?

A. The National Park Service, the U.S. Forest Service and the Virginia Department of Wildlife Resources are charged with making decisions about how to manage our natural resources in the face of multiple threats. We provide them with comprehensive information about the suitability of the streams from a water quality standpoint. We also provide this information to the Environmental Protection Agency, which reports back to Congress about the repercussions or the benefits of the Clean Air Act and ultimately, that reinforces the importance of maintaining our air-pollution standards.

Q. Has the coronavirus pandemic had an impact on the environmental changes you’re seeing in the streams?

A. Acid deposition is mostly a function of emissions from fossil fuel combustion, and local vehicular emissions also contribute. We have spoken with folks in the EPA who track emissions, and their preliminary data have shown acid emissions were lower in the first quarter of 2020. Acid deposition probably decreased as well, but we’re not likely to see that in our streams that quickly. We’re dealing with a recovery from decades of deposition, so a small change in one year is not going to show up right away. That is something the EPA has gotten a group together to look at in the Eastern U.S., but my guess is that in our region we won’t see anything immediate.

Q. Who’s going to be participating in the survey, and what types of work will they be doing?

A. This work is and has been a collaborative effort with the Trout Unlimited chapters throughout Virginia. Based on where their region is, we have assigned each of 13 chapters anywhere from 20 to 50 sites within their region. There’s one coordinator for each chapter, and their job is to pair up their chapter members with sites so they can collect samples for us. We do online training on how to collect the samples; provide the sampling materials, including detailed directions to the sites; and then, basically, it’s kind of a blitz. We have a one-week sampling window, and at that time, all of chapters throughout Virginia will make sure their individual volunteers go out and collect samples for approximately 380 sites (in addition to our regularly sampled quarterly sites) and then get them back to UVA.

We will analyze all the samples in our lab on campus, and within the next year, we’ll present the findings to the TU chapters and make the data publicly available.

Q. If somebody wants to get involved in the in the survey, how would they do that?

A. If they are interested in collecting a stream sample, they would go online to the volunteer signup page. There’s a sign-up table that shows you what sites have and haven’t been assigned. If they are interested in sampling any of the remaining sites, they can go to the maps page to get a general idea of where those sites are located and contact the coordinator for that region.

Another way to help out, for those who are interested, is to donate to help cover laboratory expenses.