Earth & Sky

The following individual(s) were interviewed for today’s show. Our thanks to:

Dawn Kirk, Forest Fisheries Biologist George Washington & Jefferson National Forest Natural Bridge Station, VA

The following books, articles and web sites were used in preparing this script:

St. Mary’s liming project website

Author’s Notes:

The emission of sulfur dioxide from power plants – a major source of acid rain – have been reduced in recent years, compared to their high levels of a few decades ago – basically this was done largely by adding scrubbers to the stacks.

Interview with Dawn Kirk, Forest Fisheries Biologist George Washington &
Jefferson National Forests

E&S: Can you explain the origins of the acid rain, and how far away its
source is?

DK: A lot of the acid rain that falls in this area comes from the Ohio
River Valley, which is a couple of hundred miles west of here. That would
probably be where the bulk of the acid deposition comes from, but of
course, there are power plants here in Virginia that contribute to it, and
everybody’s car contributes to it. But we happen to be downwind from a lot
of the big industries in the Ohio River Valley.

E&S: The substances causing acid rain, are they coming from the sky or are
they being seeped out of groundwater into the streams?

DK: It’s coming from the sky.

E&S: It’s all stuff that’s recent?

DK: Right. Most of what we have here is acid deposition from the sky, in
[the form of] particulate fallout or associated with rain, fog or snow.
There’s problems with acid rain drainage, but that’s a whole other topic.

E&S: What are the chemicals causing it?

DK: Sulfates, SO2. And nox chemicals, like NO2 and NO3 chemicals.

E&S: What is it about the geology of that area that makes it so susceptible?

DK: It’s a quartzite-type bedrock, very hard bedrock, without a lot of
buffering capacity. It doesn’t have a lot of carbonate in the rock itself.
So acid deposition falls on bedrock, or soil derived from the bedrock, that
doesn’t have a lot of carbonate rocks to neutralize the acid before it gets
into the streams, or the groundwater.

What’s interesting is that you talk to a lot of people and they say, “oh
gosh, acid rain, is that still a problem? I thought we took care of that in
the ’70s?” And it was a big problem 20 to 30 years ago in the Adriondacks,
and it still is a problem there. It’s just that that area acidified a lot
faster – because of glaciation, they did not have a lot of deep soil.

In the Appalachians, we have deeper soils because we weren’t glaciated in
the mid- to southern Appalachians. You can think of the watershed as a big
sponge that would soak up some of the acid. But now, the thinking is that
it has reached the point that soils in the watershed can’t soak up anymore,
so [acid] is showing up in the streams and the lakes, especially in areas
where the geology does not have a lot of buffering capacity. In the karst
areas where are caves are, there’s limestone, that’s calcium carbonate, and
so it is not a problem, and we still have really high pH [in the water].

E&S: To clarify … back to what you said about the Adriondacks, you said
that’s had a lot of glaciation so there is not a lot of deep soil – is
that what you said?

DK: Yes.

E&S: So the runoff occurs a lot faster then, and because of that, acid rain
gets into the stream immediately and is washed out?

DK: Yes, they [the Adriondacks] don’t have that deep soil to act as a
buffer to the streams, so it gets into the streams a lot faster. They did
not have the soil to act as a buffer to the acid rain that was being put
into the watershed.

E&S: So it’s still a problem there [Adriondacks]?

DK: Oh, yes.

E&S: But is it more serious in the Appalachians? Or is it equally bad?

DK: I think it is alarming to people in this area because they didn’t think
it was something that could affect them. It has just taken a longer time,
and it will probably be a slower process here. However, it is no less
serious because we have streams where we’re losing the fish and insects
because of [acidity]. It’s a longer process here.

E&S: The problems you’re having with the streams that you’re working on
[treating with limestone], how long has it been going on?

DK: They have been documenting the decline of pH since the ’80s. I’m not
sure they were really aware of it much before then. Since 1989, the
University of Virginia, the Forest Service, and the Virginia Department of
Game and Fish have had a project where they were looking specifically at
headwater trout streams and water chemistry of those streams. Headwater
trout streams … were more vulnerable because they didn’t have the
buffering capacity. So there’s been a project since 1989 to get the water
chemistry of different trout streams in Virginia and it has shown a decline
in not only the pH but also the acid neutralizing capacity of a lot of
associated water chemistry parameters.

This [data] was used to build a model showing how the water would respond
to acid deposition. With the new regulations in the 1990s, the Clean Air
Act, [the model] would show the amount of reduction, and what the water
chemistry would be in so many years. Basically what they showed was we need
an 80% reduction of what we have even now for it to make any difference in
the water, and that we will expect in 40 years or 50 years, say, to
probably lose half of our trout streams. So it’s going to take a lot more
reduction than what we’re seeing now in order to see any increase in health
of our streams.

E&S: The fact that you’d need an 80% reduction, that does not sound
realistic ….

DK: No, it’s really sad.

E&S: What was the motivating factor for adding limestone to some acidified
streams?

DK: The motivating factor we had for the St. Mary’s project was that it
wasn’t realistic that we were going to see a reduction [in air pollution]
before we lost a lot of the aquatic life in the stream. That stream had
been studied, and they even had data from the 1930s and the ’70s, and it
was studied intensively since the ’80s. We went from about 13 fish species
down to basically one. And we had a 40% to 50% decline in the aquatic
insect fauna diversity, we lost almost half of the insect species. This
loss was associated with a decline in pH … the most acid sensitive
species were lost first. [We did the liming] because it’s in a wilderness
area, that it was a human-induced problem, the acid deposition, that was
causing it, and we had a tool, the liming to help curb the problem of
acidification. Basically, the whole goal was to hold the pieces of the
aquatic system together until hopefully, sometime in the future, something
can be done. Maybe we will see a reduction enough where we don’t have to do
this, we don’t have to keep liming forever.

E&S: How many streams are you working on right now in the liming project?

DK: The first one that was done on the forest was in ’89 or ’90, and we
have about a half-dozen streams on the forest that have been limed in the
past 10 years. We’re not going to treat every stream that has become
acidified. We’ve done it for very specific purposes, we cannot see doing
this everywhere, we don’t want to and we couldn’t afford to. It’s a
band-aid treatment … because we’re not fixing the problem. But this is
the tool we’re going to use for a few stream so we could save the fish.

E&S: You mentioned 6 or more streams on the forest that have been limed,
and how are those streams doing?

DK: Good. The first one I mentioned that had been limed, Little Stony
Creek, was done as an experiment. They limed the stream and they watched
the insects and the fish come back. They wanted to see how long the
treatment would last. So they monitored it intensively, the fish, the
insects, the water chemistry, they monitored it intensively to see how the
decline was [occurring]. Basically after about 7 years, it was in decline
and back to pre-treatment conditions. So this liming isn’t something that
can be done once.

The whole idea is to replace the lost buffering capacity in the stream
system by adding a specific grade of limestone … the quarry that’s mining
the limestone has almost pure calcium carbonate, about 98% to 99% calcium
carbonate. And what we want is a specific size, we don’t want it to be too
small because we don’t want it to be washed away. And we don’t want it too
large because it needs to be moved by the stream and incorporated along the
stream, so you have an abrading action on the limestone or it will get
coated with metals or other compounds from the water, so you want that
abrading action to keep the [limestone] surface clean so it will release
calcium carbonate.

E&S: I don’t fully understand what you mean by not keeping them too large.

DK: The particle size that we’re using is sand-sized. You don’t want to use
a gravel because the smaller particle [sand-sized] has a higher surface
area to volume ratio and they have more of the particle exposed to the
water at any one time. If a particle is too big, the stream can’t move it.
The idea of what we’re doing is that we’re taking sand-sized particles and
placing it directly into the stream, and the water will move it and spread
it out 200 to 300 meters. It does not coat the entire stream bottom, it’s
in pockets here and there. You want it to be moved by the water readily, so
it can abrade and rub against the other rocks to keep the surface clean,
otherwise it will be coated with things like other metals and other
particles.

E&S: So in the case of Little Stony Creek, have you gone back and added
more limestone, you’re continuing that project?

DK: Yeah. After all the information was collected over so many years on
that stream, once it went back to pre-liming conditions, we decided … it
was an important fishery .. and was easy to access for vehicles to lime it.
[After liming], it responded very well, the fish responded well.

E&S: When you talk about the recolonization of insects and fish, where are
they coming from?

DK: A lot of them come as you head off the mountains and go downstream
where usually, the water chemistry improves. It’s picking up some more
[naturally occurring] limestone, the stream gets larger, and the water
chemistry works better. A lot of these fish and insects are still there
within the watershed, they’re just further downstream – they may not be in
the majority of the stream, or they may be in adjacent drainages.

In St. Mary’s, in the past 2 years, we have seen some of the species like
the dace and sculpin [return], which were not found in years and years …
they have come back. They have moved back up as soon as the water chemistry
became suitable, and they moved back because the habitat is still there.
St. Mary’s river flows into a river that joins another one that makes the
South River which runs through bottom-lined limestone. So there are fish
found further downstream where the water chemistry becomes favorable.

E&S: Has there been a case where a species has been completely extirpated
from one of these streams because of acidity? Some species can only live in
specific types of habitats.

DK: Back in ’93, we were doing some monitoring of macroinvertebrates and
went to this one steam that was up in the mountains, nothing really much
going on around it. The insects were really terrible, really poor. When we
took a water chemistry sample, we saw it was very acidic. We went back and
shocked for fish, and there were no fish. Brook trout are in this area,
they are most acid tolerant, and they weren’t even in this part of the
stream. So in ’93 we limed the stream, and carried trout and other dace
back up into that part of the stream because there were some fish barriers
downstream, so they could not colonize on their own. We carried them up,
and restocked that section with native fish in that part of the stream. And
they did great. We went in and sampled the next year, and we had increases
in populations in that stream.

E&S: You mentioned earlier that St. Mary’s had gone from 13 species to 1
species.

DK: Certainly not all 13 species were found throughout the stream, there
were some found in the lower reaches where the water was a little bit
warmer, and when you get into the headwaters of St. Mary’s river, you only
had trout and blacknose dace, and probably sculpin. But several of the
species were reproducing rainbow trout, reproducing brown trout, that were
stocked for years in that stream. The brown and rainbow trout were gone
because they’re more sensitive, and we did not have plans to restock them.
We’re not going to put them back in there. So we won’t ever get those 13
species back, because some of them were not native species.

E&S: You said earlier there were about 6 streams that were limed, and
they’re all doing well and being recolonized … how expensive is it to
lime these streams?

DK: That’s the beauty of this technique, that it’s not expensive. The
limestone itself is relatively cheap. The large expense, the biggest cost,
comes from getting the material out to the streams. For all the cases
except for St. Mary’s, we had vehicle access, like at Little Stony Run,
where a road crosses it so you can bring trucks to where the road crosses
it. And it might cost a couple of thousand dollars for treating several
miles of stream, that’s really great for treatment that lasts up to 5
years. That’s fantastic.

The problem is that for St. Mary’s, we did not have road access, so we used
helicopters and that’s where the big cost came in. We put in 140 tons of
limestone which in itself was only a couple of thousand dollars to
purchase. To get it hauled … it took 4,000 dollars in hauling costs
because we brought it from a plant that was a couple of hours away. We
wanted a specific grain of limestone so we were willing to pay for it to
get it from further away. So that in itself would not have been very
expensive except we had to pay for the helicopter.

E&S: In general, the streams you are treating are 5 miles or so, is that
the average stretch?

DK: Yeah, probably the smallest one would be about 3 miles, and for St.
Mary’s we treated about 11 to 12 miles worth of stream.

E&S: That’s the largest?
Yeah, and for that one, we had six different streams that we treated. We
treated the upper St. Mary’s itself and five other tributaries. That’s what
was really neat about that place, not only was it wilderness, but we
treated the stream itself and the tributaries.

E&S: This is separate from the other streams on forest land that were treated?

DK: Right.

E&S: In cases where acid rain has had a big impact on particular streams,
have you seen a big problem along the riparian areas?

DK: We haven’t seen a problem along the riparian areas. Although there are
places like, I think this is documented, in the Great Smoky Mountains,
where there is a lot of fog on top of the mountains, and the fog itself can
be very acidic, and it can effect the trees. But we haven’t seen problems,
other than the aquatic life.

E&S: I was wondering about the food chain, I was wondering about the impact
on birds or ….

DK: Yes definitely on that … I was thinking of plants. [Animals]
depending on insects or stream fish would be affected.

E&S: … and bats feed on insects along streams …

DK: Yeah.

E&S: When you dump the limestone, do you only put it in one location or in
several different locations along the stream?

DK: We’ve been putting it in one location along the stream.

E&S: And then letting it wash down a bit?

DK: Yeah.

E&S: Earlier on, you said you could not do it for all the streams because
it’s not really a solution. But you also said it was a way to keep these
fish around till you can find a solution.

DK: Right. Long-term, hopefully, there will be [a solution] … where we
can clean the air enough, or we have the technology so we won’t be
polluting the air and we won’t have acid deposition as much as we have
right now. Certainly talking with a lot of people who do this stuff, it
would be easier to try to keep pieces of this aquatic biota here now rather
than, say, 40 years from now, when the air gets cleaned up, to try to find
a species and put them back in the streams.

E&S: Why have you selected just six streams, why not more?

DK: Because, in the case of Little Stony Run, and some of the other
streams, we had a significant wild trout fishery in that area. We decided
that we want to preserve a stream because it’s a significant fishery. In
the case of St. Mary’s, we want to preserve that stream because it’s in a
wilderness area, and we want to preserve all the pieces in the wilderness
area. It’s not that we don’t care about the other streams, but we can’t
save them all.

E&S: I guess I’m trying to understand the criteria for selecting streams
… by basically saying it’s either a fishery or a critical wilderness area
with high biodiversity?

DK: It would be something like a fishery or because of aquatic diversity,
There’s some ponds we have on the forest that are naturally acidic, but
becoming more acidic [due to acid deposition]. We have very unique
assemblages of amphibians and some insects that are not found anywhere else
in Virginia. If it becomes too acidic for these organisms to reproduce,
what are we going to do? In that case, [liming] would be for rare species,
to help maintain the habitat of rare species.

E&S: You are continuing to monitor other important areas?

DK: We will look at it, and evaluate it to see whether or not we need to
take action.

- end of interview –