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Water Issues Part 3: Dams Revisited (A Geology Re-Release) · PlanetGeo: The Geology Podcast

0:03
SPEAKER_02: Welcome to Planet Geo, the podcast where we talk about our amazing planet, how it works, and why it matters to you.
0:14
SPEAKER_02: All right, we're going.
0:15
SPEAKER_02: Okay, let's go.
0:16
SPEAKER_02: Chris, here we go.
0:18
SPEAKER_02: How are you?
0:19
SPEAKER_02: I'm great, man.
0:19
SPEAKER_02: I'm great.
0:20
SPEAKER_02: You're back in Michigan.
0:21
SPEAKER_02: Back in Michigan.
0:22
SPEAKER_02: This is uh right around Christmas time.
0:24
SPEAKER_02: We're recording this.
0:25
SPEAKER_02: Um, super fun.
0:26
SPEAKER_02: Great holiday break.
0:27
SPEAKER_02: Great to kind of see some people, you know, not everybody, not big gatherings, but you know, you know, it's good.
0:34
SPEAKER_01: You've kind of been all over the map lately.
0:36
SPEAKER_01: You were in New Orleans a couple weeks ago.
0:38
SPEAKER_02: Yeah, yeah.
0:38
SPEAKER_02: We, you know, got uh did got all the jabs and felt safe and traveling and all that stuff.
0:43
SPEAKER_02: And uh yeah, we we kind of went to see family in Colorado and now in Michigan, it's all good.
0:48
SPEAKER_02: Everybody's safe and healthy so far.
0:49
SPEAKER_01: So from Louisiana to Colorado to Michigan, back to Pennsylvania soon.
0:54
SPEAKER_02: Back to Pennsylvania.
0:54
SPEAKER_02: I know.
0:55
SPEAKER_02: Headed back, headed back soon.
0:57
SPEAKER_02: So we are um doing Dams Part Two right now.
1:00
SPEAKER_02: Re-release.
1:01
SPEAKER_02: We just decided this, by the way.
1:02
SPEAKER_02: We we now have a four-part series on water uh that we are re-releasing.
1:07
SPEAKER_02: But what we're doing right now, what we're actually working on, we're working hard in the background here, even though we are re-releasing stuff.
1:12
SPEAKER_02: We're getting ready for a very exciting season two, or maybe season two and a half or something like that, of Planet Geo.
1:19
SPEAKER_02: Yeah.
1:19
SPEAKER_02: And also working on some cool stuff in the background that we'll we'll talk about later in the year once it once it comes out.
1:24
SPEAKER_01: Yeah.
1:25
SPEAKER_02: But Dams part two, what do we got, Chris, today?
1:28
SPEAKER_01: Um, I don't know.
1:29
SPEAKER_01: We this came about because you read an article and then we actually had a listener question that went back to the dams episode or something related to that.
1:40
SPEAKER_01: And so we just decided to dive a little bit deeper into dams and highlighting some more specific issues that can happen.
1:48
SPEAKER_02: Yeah, so this is really a follow-up to the the episode that you listened to last week about dams is sort of an intro and infrastructure.
1:55
SPEAKER_02: And uh, you know, this is a little bit more about what happens to streams as dams when we put dams in place and sort of the problems that might it might cause and the benefits of dams.
2:04
SPEAKER_01: Or when we remove dams.
2:05
SPEAKER_01: Or when we remove it.
2:05
SPEAKER_01: What happens to streams, you know, upstream, downstream, and so on.
2:08
SPEAKER_02: Absolutely.
2:09
SPEAKER_02: So, dams part two coming at you today.
2:12
SPEAKER_02: Follow us on social media, send us an email, planetgeocast at gmail.com, leave us a rating and a review.
2:18
SPEAKER_02: We love that stuff, it really helps us.
2:19
SPEAKER_02: Yeah, let's go.
2:20
SPEAKER_02: Let's do it.
2:35
SPEAKER_01: All right, Jesse, how are we doing today?
2:38
SPEAKER_02: I'm good.
2:39
SPEAKER_02: I'm looking at you, but apart from that, uh I'm pretty good.
2:44
SPEAKER_01: Sometimes, sometimes working with you, I got I have to rethink this whole thing, honestly.
2:48
SPEAKER_01: Um, I ask you a very simple question and you look at me like I had a horn grown out of my head.
2:54
SPEAKER_01: Just then how you do it, and you gave me this weird look.
2:58
SPEAKER_01: Um, okay.
2:59
SPEAKER_02: Well, anyway, sometimes you behave like you have a horn growing out of your head, though.
3:02
SPEAKER_01: So I'll all right, I'll take it.
3:04
SPEAKER_02: Well, what do we got today on Planet Geo, Chris?
3:07
SPEAKER_02: I'm pumped about this episode.
3:08
SPEAKER_01: Well, today we are gonna revisit dams.
3:12
SPEAKER_02: Okay, let me let me set the stage from my perspective because you had to talk me into, you had to really talk me into our first episode on dams.
3:20
SPEAKER_02: I mean, that took a lot of effort.
3:22
SPEAKER_02: We almost broke up.
3:23
SPEAKER_02: We we almost had a big breakup about whether we're gonna do an episode on dams or how we're gonna do it, right?
3:29
SPEAKER_02: And I must say that was a great episode.
3:31
SPEAKER_02: Listener, go back and listen to the damn episode.
3:34
SPEAKER_02: Uh, I think it was around Christmas time.
3:36
SPEAKER_02: Oh, that was a great episode.
3:38
SPEAKER_01: I think it was.
3:38
SPEAKER_01: It was a super important topic.
3:40
SPEAKER_01: Totally, totally important topic.
3:42
SPEAKER_02: And I mean, we did not do it justice because you can't in a half an hour, right?
3:46
SPEAKER_02: This is a huge topic, a really important topic.
3:49
SPEAKER_02: And so we're revisiting it here, and I'm really excited about it.
3:52
SPEAKER_02: Really excited about it.
3:54
SPEAKER_01: Me too.
3:54
SPEAKER_01: But hey, before we do that, we should probably redo some introductions.
3:57
SPEAKER_01: That's right, right?
3:58
SPEAKER_01: You are Dr.
3:58
SPEAKER_01: Jesse Rymank, you're one of my former students back 20 years ago in September.
4:04
SPEAKER_01: It'll be 20 years when you were sitting as a young 14 or 15-year-old awkward kid in my class.
4:09
SPEAKER_01: Um, and you went out and get your PhD in geology, and uh now you are a professor of geoscience at Penn State University.
4:17
SPEAKER_02: Yeah, and you're Chris Belhuis.
4:19
SPEAKER_02: You are a nationally recognized earth science teacher from Michigan.
4:23
SPEAKER_02: I was sitting in your class a long time ago.
4:25
SPEAKER_02: You taught me many of the basics of geoscience that I still use today in my everyday life.
4:30
SPEAKER_02: And uh, you know, we've been really good friends for a long time now.
4:32
SPEAKER_02: And and uh doing this podcast, Planet Geo, this is uh a really fun thing to do together, and I think a really important thing as well.
4:40
SPEAKER_01: That I guess remains to be seen yet.
4:42
SPEAKER_01: We'll see.
4:42
SPEAKER_02: That's right, that's right.
4:43
SPEAKER_02: You know, so all right, we're also the the other the last thing, the rat last reason that we're revisiting Dams is because you didn't quite get to finish some of your rambling that you know in the previous episode.
4:55
SPEAKER_02: So this is listener, uh, you might get a bit of Chris rambling in this episode.
5:01
SPEAKER_02: We're gonna try and tamp that down.
5:03
SPEAKER_02: I'm gonna try and interject and prevent long-winded rambles, but I can't promise that I'll be able to keep him in check.
5:10
SPEAKER_02: So stay with us.
5:12
SPEAKER_01: All right, all right.
5:13
SPEAKER_01: It's good stuff, though.
5:15
SPEAKER_02: So says the rambler.
5:16
SPEAKER_01: Well, also, you hey, it this had to do with an article that I think you actually read.
5:23
SPEAKER_01: You you came across something and you spit it back to me, and uh that's really what prompted this.
5:28
SPEAKER_01: Yes, I did not get to finish some of my ramblings about dams.
5:32
SPEAKER_01: However, we also had an interesting article that we thought, yeah, you know what, let's let's round this off.
5:38
SPEAKER_01: Let's uh let's finish.
5:39
SPEAKER_02: So we're gonna throw a link to this EOS.
5:40
SPEAKER_02: It's EOS is the article, but it's the science news by AGU Journal.
5:44
SPEAKER_02: There's a link to it in the show notes.
5:45
SPEAKER_02: So click on that if you want to read the article, and there's a bunch of articles uh are broadly around this topic um in the show notes.
5:52
SPEAKER_01: So let's do a little bit of review for the people that are not gonna go back and listen to the episode that we did uh a while back.
5:58
SPEAKER_01: Um we talked about some things with dams in particular.
6:02
SPEAKER_01: Like we talked about the sediment accumulation that happens on the upstream side of the dam in the reservoir.
6:09
SPEAKER_01: Okay.
6:10
SPEAKER_01: And if this issue, the sediment accumulation is mismanaged, it can put the whole reservoir and the entire ecosystem at risk.
6:19
SPEAKER_01: And so that was a big part of the article that we read.
6:23
SPEAKER_01: And it was it was really kind of cool.
6:25
SPEAKER_01: They had this the this Payonia dam in Colorado, they had a picture of it and this inlet tube that which we I think we need to let's paint a picture of this.
6:33
SPEAKER_02: Yeah, let's let's paint a picture of it.
6:35
SPEAKER_02: Yeah, yeah, yeah.
6:35
SPEAKER_02: Basically, the the filter, or not really the filter, but uh think of like a hot tub or a pool, right?
6:41
SPEAKER_02: It there's an intake, there's a water intake that goes into the pump, it gets cleaned.
6:46
SPEAKER_02: This is the water intake that then gets funneled through the hydropower, through the damn system, and out the other side.
6:53
SPEAKER_01: So this is really the Wow, that's a really good analogy.
6:56
SPEAKER_01: The hot tub one, you shocked.
6:58
SPEAKER_01: There you go.
6:58
SPEAKER_01: It's because that's exactly what it is.
7:00
SPEAKER_01: It sits on top, right?
7:02
SPEAKER_01: This inlet for a hot tub sits on top and it's kind of on this bobber that can go up and down according to how much water you have in the hot tub.
7:09
SPEAKER_01: Because you know, you want the inlet or this intake at the top because all the stuff is going to settle down to the bottom.
7:16
SPEAKER_01: You're taking cleaner water then, which won't clog up your systems as you run it through the hydroelectric parts of the dam and all that kind of stuff.
7:24
SPEAKER_01: You're taking clean water, and so you have this tower that goes from the bottom of the reservoir, it's right behind the dam, usually, is real close to the dam.
7:33
SPEAKER_01: And the outflow is at the bottom of the tower.
7:36
SPEAKER_01: The intake pipe is at the top where water just kind of skims over the top and down this tube, and then it goes to and through the dam.
7:45
SPEAKER_01: Does that make sense that I'm painting a picture there?
7:47
SPEAKER_02: Totally, totally.
7:48
SPEAKER_02: It's a tower that draws water in and it sits in the lake somewhere, right?
7:52
SPEAKER_02: Typically.
7:53
SPEAKER_01: Yeah.
7:53
SPEAKER_01: So this inlet for the Peonia Dam in Colorado sits on top of a 21 meter high tower.
8:01
SPEAKER_01: Yeah.
8:01
SPEAKER_01: So, you know, that's like 70 feet-ish.
8:05
SPEAKER_02: So think of it this way: think of it when you're building the dam, this is 70 feet above the dam bot or the lake bed, the original like stream bed, right?
8:13
SPEAKER_02: So it's 70 feet above the valley floor, and then that is filled up with water.
8:18
SPEAKER_02: Whenever the dam forms, it fills up with water, and so it's 70 feet above the lake bottom or the reservoir bottom.
8:24
SPEAKER_01: But now this tower is clogged with sand.
8:28
SPEAKER_01: So the sand has completely filled up the lake after only 50 years.
8:34
SPEAKER_01: 50 years is what it's like.
8:35
SPEAKER_02: It's amazing how fast this sediment accumulates in these lakes, because that reservoir is full of complete, like completely full of sediment.
8:44
SPEAKER_02: It's totally choked now, and you can't really use the dam.
8:47
SPEAKER_01: Continuing on, right, with review.
8:49
SPEAKER_01: So, what else do dams do?
8:52
SPEAKER_01: Why else do are dams built and so on?
8:54
SPEAKER_01: Well, we talked about this in the earlier episode, but dams are for recreation, they're for flood control, they're for hydroelectric power, they're for water, for both for irrigation and domestic use.
9:06
SPEAKER_01: And in addition to storing water in this reservoir, they also store sediment.
9:12
SPEAKER_01: And they store a lot of sediment, as we just talked about with this dam in Colorado.
9:17
SPEAKER_01: Why does this happen?
9:18
SPEAKER_01: Just for review's sake, Jesse, why does sediment accumulate in this reservoir?
9:23
SPEAKER_02: When water's flowing rapidly, think of your favorite stream, and we're going to keep coming back to your favorite stream.
9:28
SPEAKER_02: So think about your favorite stream while we're going through this episode.
9:31
SPEAKER_02: But it's carrying little pebbles, it's carrying sand grains, it's carrying silt, it's carrying uh a whole bunch of sediment.
9:38
SPEAKER_02: And when that stream slows down, all of a sudden that water cannot hold that sediment anymore.
9:44
SPEAKER_02: And that sediment settles out and it just settles and it's dumped wherever that water stops.
9:48
SPEAKER_02: So as soon as the water stops, it dumps all the sediment.
9:51
SPEAKER_02: In a dam or in a reservoir, we're kind of artificially stopping the flow of sediment.
9:56
SPEAKER_02: And so all that sediment would normally be deposited eventually in the ocean.
10:01
SPEAKER_02: When we put a dam in the way, it gets deposited in this reservoir and it gets deposited pretty quickly.
10:06
SPEAKER_01: Because the speed of the river keeps this sediment lifted in suspension, you know, it keeps it moving downstream.
10:13
SPEAKER_01: So when it comes to a standstill, this stuff just gets deposited.
10:16
SPEAKER_01: Well, then what this does then, if you if you don't manage this sediment accumulation issue, the storage capacity of the lake, of the reservoir behind the dam, is greatly diminished, right?
10:29
SPEAKER_01: It's estimated now the numbers vary quite a bit on this, but dependent on geography.
10:34
SPEAKER_01: But the US dams have been reduced by an average of about 25%.
10:40
SPEAKER_01: In other words, they're not able to store as much water, 25% less water, because that space in the lake is taken up with sediment.
10:48
SPEAKER_02: Let's kind of put like a model system here.
10:50
SPEAKER_02: Let's say you want to build this dam and you're gonna build a lake, a reservoir that's 100 feet deep on average.
10:57
SPEAKER_02: Let's say it's 100 feet deep, you're gonna build a dam that's like, let's say it's 150 feet high, uh, because you want to have, in case there's a flood or something, you don't want your dam to break.
11:06
SPEAKER_02: So you build it too high for the reservoir.
11:08
SPEAKER_02: So it can store 100 feet times the area of the lake.
11:11
SPEAKER_02: That's how much water it's storing.
11:13
SPEAKER_02: Now, what this is saying is basically this river, the river that's feeding that reservoir, has reduced the storage capacity of that reservoir.
11:22
SPEAKER_02: So that reservoir could go, it's normally at 100, it could go up to 150 without the dam breaking.
11:27
SPEAKER_02: Now there's sediment, there's 25 feet of sediment in the base of that thing, which means that the storage capacity is significantly less.
11:35
SPEAKER_02: It means that if there's a flood event, it means that this dam could break because there's so much sediment in there, it just can't hold as much water.
11:42
SPEAKER_02: The volume in this reservoir is diminished because there's sediment piling up in the bottom.
11:47
SPEAKER_02: Yeah.
11:47
SPEAKER_01: So if you leave it alone, you don't do anything with the sediment, then the entire reservoir is going to fill in, rendering the entire dam now useless.
11:57
SPEAKER_02: That's right.
11:57
SPEAKER_02: And dams are really important because they play a huge role in the energy transition, you know, getting on the decarbonization of our economy.
12:05
SPEAKER_02: There are proposals for Massachusetts specifically to draw hydropower from Canada, from the the province of Quebec.
12:13
SPEAKER_02: Um, and and you know, hydropower has 5% of the lifetime greenhouse gas emissions compared to natural gas.
12:21
SPEAKER_02: So, really, it's it's really relative, quote unquote, clean energy.
12:24
SPEAKER_02: It's relatively clean energy, hydropower is, and but it requires a reservoir.
12:29
SPEAKER_02: And so when we think about the lifetime of reservoirs, the sediment is a big problem.
12:34
SPEAKER_01: Okay, so let's talk then what happens with the water that comes out of the other side of the dam, the downstream side of that dam.
12:41
SPEAKER_01: Well, that water is sediment poor, it doesn't have anything in it, it's coming out as clean water.
12:48
SPEAKER_01: And you described it last time in our previous episode perfectly as that's hungry water.
12:53
SPEAKER_01: Okay, that that water is fast and it's very erosive.
12:57
SPEAKER_01: It's looking to pick up sediment.
13:00
SPEAKER_01: And so upstream from the dam, you have you know sediment deposition issues.
13:05
SPEAKER_01: Downstream from the dam, you're gonna have erosion issues due to the lack of sediment in the water.
13:11
SPEAKER_02: This is one of the best terms in geology, I think.
13:13
SPEAKER_02: Hungry water, because it just describes it perfectly.
13:16
SPEAKER_02: This water is looking for stuff to pick up, it's hungry, and it does a lot of damage on the way down.
13:21
SPEAKER_01: Now, so let well I was just gonna say that you know, this lack of sediment then, in our last episode, we were ripping on biology a little bit, but this actually plays in.
13:30
SPEAKER_01: You said it before that river that has sediment is a is a healthy river, and it's also a healthy ecosystem.
13:37
SPEAKER_01: And so this lack of sediment downstream from a dam, these issues also need to be accounted for because it puts these habitats and these ecosystems at risk, also.
13:47
SPEAKER_02: So let's get into that a little bit, and we're gonna use the term here, which is the term of the this the field of study, which is fluvial geomorphology.
13:55
SPEAKER_02: And we're gonna dive into this, but because it's related to fishing, I think it's useful to kind of break this down a little bit.
14:01
SPEAKER_02: I do too.
14:01
SPEAKER_02: Fluvial is just river, so that just means running water or rivers.
14:06
SPEAKER_02: Geo is earth, and morphology is the morph, morpho is shape, and ology is the study of.
14:12
SPEAKER_02: So, really what we're doing is we're studying the earth shape that is due to running water.
14:19
SPEAKER_01: You and I both know we're very good friends with a fluvial geomorphologist.
14:24
SPEAKER_02: Uh, you know, as scientists and geologists are not immune from this, but we need to make up some terms just to make it sound fancy.
14:31
SPEAKER_02: I mean, it's not really fancy, it's thinking about rivers, you know, which is a great thing.
14:35
SPEAKER_02: And so, you know, all right, let's get into some of the details of fluvial geomorphology and picturing your favorite river here.
14:42
SPEAKER_01: Okay, so getting specific with some fluvial geomorphology.
14:46
SPEAKER_01: We're gonna get into some terminology here, but any good angler can easily recognize these because these things that we're gonna talk about provide a habitat and provide a habitat for what they're after.
14:57
SPEAKER_01: Beyond that, though, Jesse, being able to recognize and understand the sequence of things that you see in your local river, it just like it makes you think about things in a way that you wouldn't otherwise think of.
15:11
SPEAKER_01: We're gonna talk about the parts of a river and the habitats that these things provide.
15:16
SPEAKER_01: And that's one of the things about this podcast, right?
15:18
SPEAKER_01: This is why we're one of the big reasons why we're doing this is to get people to look at things a little bit differently because you know what?
15:24
SPEAKER_01: You can't think about words you don't know.
15:26
SPEAKER_01: And so this is going to, I hope anyway, make people think about things and see things a little bit differently because of these terms.
15:35
SPEAKER_02: That's right.
15:35
SPEAKER_02: And and you know, these terms we're gonna use, these are also fishing terms.
15:38
SPEAKER_02: I really like fishing on beautiful rivers, and you know, fish like to hang out in some of these places, they don't like to hang out in other places.
15:45
SPEAKER_02: So we're gonna get into some terminology that fishermen know, and it's because you know it really impacts where you cast your line, where you want your fly to drift through, right?
15:55
SPEAKER_02: So, and and there are differences region to region, but in general, all these terms remain the same.
16:00
SPEAKER_02: So, Chris, we're gonna get into some of the terminology here, and then we're gonna talk about how dams really upset this sort of equilibrium.
16:09
SPEAKER_02: Um, we need to get some basics of stream morphology first before we can come back to dams and how they impact it.
16:15
SPEAKER_01: But before we do that, you want people to envision a stream.
16:19
SPEAKER_01: So, what stream are you thinking of when we're talking about these things?
16:22
SPEAKER_02: Yeah, so I'm gonna picture Spring Creek, which is in State College, Pennsylvania.
16:26
SPEAKER_02: It's you know very good for trout fishery, but it's also very close to me.
16:29
SPEAKER_02: Uh, it has all these features.
16:31
SPEAKER_02: I've run along it, I've fished on it a lot.
16:34
SPEAKER_02: So that's what I'm thinking of.
16:35
SPEAKER_02: Chris, what what stream are you gonna think of here?
16:38
SPEAKER_01: So I'm just thinking of a little stream, it's called Buttermilk Creek, but that runs right in between the two campuses at the school I teach.
16:45
SPEAKER_01: And I was walking across the bridge the other day, and we, you know, we were putting together this episode here, and I'm I stopped in the middle of it.
16:51
SPEAKER_01: I'm like, oh, look at that.
16:52
SPEAKER_01: And it, you know, just you can right there in this little tiny 10-foot-wide stream see exactly what we're talking about.
16:59
SPEAKER_01: Again, making you think about things that you otherwise wouldn't.
17:02
SPEAKER_02: That's right.
17:03
SPEAKER_02: So think of your favorite stream or think of a nearby stream.
17:06
SPEAKER_02: It could be the Mississippi River or it could be the little buttermilk creek, you know, right next to your school.
17:11
SPEAKER_02: Doesn't matter.
17:11
SPEAKER_02: Think of that while we're going through these things.
17:13
SPEAKER_02: All right, Chris, lead us off.
17:15
SPEAKER_02: Where are we going?
17:15
SPEAKER_01: Okay.
17:16
SPEAKER_01: So where we're going with this is we're gonna talk about riffles, runs, pools, and glides.
17:21
SPEAKER_01: Those are these things, and I didn't know this, that you every angler knows these terms.
17:26
SPEAKER_01: I actually thought they know how to recognize them.
17:29
SPEAKER_01: I didn't think they knew what they were, though.
17:31
SPEAKER_02: We know these terms because we're trying to figure out where the fish live, uh where the big fish live, and and you gotta know your river uh when you're when you're doing that.
17:39
SPEAKER_02: So let's start out with riffles, and riffles are one of these things in Pennsylvania, in Spring Creek, the stream I'm thinking of, this is where the fish are.
17:50
SPEAKER_02: And these are shallow areas where the water runs pretty fast over a coarse stream bed, and we mean coarse, meaning like the size of the sediment in it.
17:59
SPEAKER_02: So these are like pebbles, boulders, gravelly stuff, and so the water flowing over the rocks gives it this sort of moderate agitation.
18:08
SPEAKER_01: So we're not talking about rapids.
18:10
SPEAKER_01: This is just more mildly agitated than rapids, right?
18:13
SPEAKER_02: That's right, it's not like white water, it's just kind of like flowing and gurgling, I would say.
18:17
SPEAKER_02: It's kind of gurgly water, and because it's agitation, the creatures, the critters that live there, they have to be able to cling to rocks because the water's flowing fairly fast.
18:27
SPEAKER_02: So things like midges, caddisflies, stone flies live and cling to the rocks there, which means that in Pennsylvania at least, the trout love this area because all the critters are there.
18:39
SPEAKER_02: Riffles also help oxygenate the water.
18:41
SPEAKER_02: So it means there's more water interacting with more air, which helps put oxygen in there, which again helps the biodiversity of the area.
18:48
SPEAKER_02: So that's what a riffle is.
18:50
SPEAKER_01: That's right.
18:50
SPEAKER_01: I'm really concerned with oxygenating water when I'm making beer.
18:53
SPEAKER_01: I've got to just make it really turbulent, gotta mix it up, get the air in there.
18:57
SPEAKER_01: There you go.
18:57
SPEAKER_01: Get those riffles going.
18:59
SPEAKER_01: That's right, that's right.
19:00
SPEAKER_01: All right, riffles, runs, pools, and glides.
19:03
SPEAKER_01: By the way, in most streams, not all, of course, but in most streams, it kind of follows that progression of riffles to runs, pools, and then glides, which lead into the glides lead into more riffles, runs, pools, and glides.
19:17
SPEAKER_01: So let's hit the runs then.
19:19
SPEAKER_01: So the runs usually follow the riffles, but not always.
19:23
SPEAKER_01: This is where the water is uh well, straighter.
19:26
SPEAKER_01: Okay, it's a in the straight part of the channel, it's a little bit deeper and it has this kind of smooth laminar flow to it.
19:33
SPEAKER_01: The flow is it's faster than what you get in a pool.
19:36
SPEAKER_01: In a pool, there's the water's relatively stagnant, it's not moving much.
19:40
SPEAKER_01: So, what you get here in this kind of smooth, faster running water, smaller fish like minnows tend to do really well here because they can't compete, they usually can't compete in the pools where the bigger fish like to hang out often.
19:54
SPEAKER_01: Does that make sense?
19:55
SPEAKER_02: Yeah, absolutely.
19:56
SPEAKER_02: They kind of get kicked out by the big fish.
19:58
SPEAKER_02: So riffles, runs, pools, glides.
20:01
SPEAKER_02: We're onto pools now, and pools are really deep, calm, surface is extremely smooth.
20:08
SPEAKER_02: It's your favorite place to jump in.
20:10
SPEAKER_02: So picture again your little creek, your favorite stream, river, whatever it is.
20:15
SPEAKER_02: Think about the place you would like love to just take a deep dive into on a summer's day.
20:20
SPEAKER_02: That's a pool, right?
20:22
SPEAKER_02: This is a favorite place, at least in the Midwest, in parts of the West, where the big trout like to hang out, the water's really calm, they don't need to burn a lot of energy.
20:31
SPEAKER_02: This is the place where you get clams and snails and a lot of worms that are burrowing in.
20:37
SPEAKER_02: So these are the the really deep, really calm sections of the river.
20:41
SPEAKER_01: Okay, all right.
20:43
SPEAKER_01: Um, there was a question I was gonna ask you, and now maybe it'll pop back into my head.
20:47
SPEAKER_01: Okay, moving on then.
20:48
SPEAKER_01: So the last part of it riffles, runs, pools, and glides.
20:51
SPEAKER_01: The glides, it this like we want you to be able to see these things.
20:55
SPEAKER_01: The riffles that we have this agitated water, then you have the runs where it's deeper than it is in the riffles, and the water's moving pretty fast, but there's not a lot of agitation at the surface.
21:06
SPEAKER_01: Then you have these calm, deeper areas where the water is uh just maybe just mildly circulating.
21:12
SPEAKER_01: Those are the pools, and then the pools usually give way to these glides, which is where you have the slow, smooth flow.
21:19
SPEAKER_01: The water's too slow to be a run, and it's too shallow to be a pool.
21:24
SPEAKER_01: And so these are like the four kind of unique things, these features that you get in rivers: riffles, runs, pools, and glides.
21:34
SPEAKER_01: They tend to occur in that order, they don't always occur in that.
21:37
SPEAKER_01: In fact, uh, this is what I was gonna say earlier.
21:39
SPEAKER_01: The after the riffles, you often can get a pool because the water kind of dives over the riffles, then it scours out this deeper area and it calms it out, and you can get a pool after the riffles.
21:51
SPEAKER_01: So uh it's not always the same, but it it works.
21:55
SPEAKER_01: Okay, so we went through this terminology of what happens with the you know, these river.
22:00
SPEAKER_01: Habitats and ecosystems created by the riffles, runs, pools, and glides, which is these natural things that rivers have, right?
22:06
SPEAKER_01: But a dam upsets this.
22:09
SPEAKER_02: Yeah.
22:09
SPEAKER_02: So what we're talking about, and again, picture your favorite stream because these riffles, runs, pools, glides, these are happening.
22:15
SPEAKER_02: This is fast water in the riffles, slow water in the pools.
22:19
SPEAKER_02: This is erosion and deposition.
22:21
SPEAKER_02: It's occurring at a pretty small scale, like you know, hundreds of feet apart, maybe you know, a mile if you're on the Mississippi.
22:27
SPEAKER_02: When we put a reservoir in the way and a dam in the way, uh, this is happening on a much, much bigger scale.
22:34
SPEAKER_02: Basically, you're getting a huge amount of slow water upstream, which is a big ass pool that is depositing all the sediment there.
22:43
SPEAKER_02: And it just really kind of disrupts this riffles, runs, pools, and glides scenario in a major, major way.
22:52
SPEAKER_01: Yeah, so the downstream side is also affected.
22:54
SPEAKER_01: Instead of getting the riffles, runs, pools, and glides, because you have a hungry river that's basically doing a lot of erosion, it creates a lot of riffles and it really destroys those other habitats that you get in the runs, the pools, and the glides.
23:11
SPEAKER_02: That's right.
23:12
SPEAKER_02: And so remember hungry water, and we actually have a nice little reel.
23:16
SPEAKER_02: If you go to our Instagram page about this, that kind of shows what we're talking about.
23:20
SPEAKER_02: But this hungry water, all right.
23:22
SPEAKER_02: So how do we mitigate against this, Chris?
23:24
SPEAKER_02: Like, what are the recommendations for dealing with this sediment accumulation upstream and this downstream degradation of that?
23:32
SPEAKER_02: What do we do about it?
23:33
SPEAKER_01: So, dredging and sediment removal, that's the easy answer, you know.
23:38
SPEAKER_01: But it's it's uh it's expensive and it does nothing for the downstream disruption that took place, right?
23:44
SPEAKER_02: Because you mean just dig out the reservoir and put it somewhere else.
23:48
SPEAKER_01: Yeah, put it out there as fill, uh, you know, fill, dirt, whatever.
23:52
SPEAKER_01: You dredge it and remove it.
23:53
SPEAKER_01: It's expensive and it doesn't do anything for the sediment issue downstream that we're talking about.
24:00
SPEAKER_01: So there are a lot of recommendations for dealing with this.
24:03
SPEAKER_01: The recommendations for mitigating sediment accumulation and downstream degradation.
24:07
SPEAKER_02: In degradation, what we're referring to here by degradation is basically the result of hungry water downstream of the dam.
24:15
SPEAKER_02: So that it's degradation, it's sediment-starved water, it's erosive, it really disrupts the habitat.
24:21
SPEAKER_02: It's changing the habitat.
24:23
SPEAKER_02: It's changing the habitat, exactly.
24:25
SPEAKER_02: So, what do we do about this?
24:26
SPEAKER_02: If we can't dredge, that's too expensive.
24:28
SPEAKER_02: What else do we do?
24:30
SPEAKER_01: Most of the recommendations include or deal with mobilizing the sediment that accumulates in the lake and rerouting the sediment either through or around the dam, right?
24:41
SPEAKER_01: And that like that makes sense because it alleviates both problems.
24:46
SPEAKER_01: It it takes care of this accumulation behind the dam.
24:50
SPEAKER_02: Yeah, it sounds totally reasonable, right?
24:52
SPEAKER_02: Pretty easy.
24:53
SPEAKER_02: I mean, at first pass.
24:54
SPEAKER_01: So it does.
24:56
SPEAKER_01: So you're asking, like you're saying to yourself, right, right, like, so what's the holdup?
24:59
SPEAKER_01: That makes sense.
25:00
SPEAKER_01: I mean, when you if we can find a way to actually flush the sediment through the dam without disrupting the hydroelectric power, all that uh kind of stuff, right?
25:10
SPEAKER_01: Why not?
25:10
SPEAKER_01: Well, first of all, you have this, there's a very long-standing, it's a misconception, but it's a long-standing misconception that sediment negatively impacts water quality.
25:22
SPEAKER_01: Okay, it's viewed as a pollutant.
25:24
SPEAKER_01: And it has to be acknowledged that sediment actually is not necessarily a pollutant unless something else happened to it, right?
25:31
SPEAKER_02: Right.
25:31
SPEAKER_02: I mean, I experienced this.
25:33
SPEAKER_02: I see a stream that's muddy, dirty water.
25:35
SPEAKER_02: I think, oh, that's gross, that's dirty, right?
25:38
SPEAKER_02: You kind of instinctively think that that's the case.
25:41
SPEAKER_01: And but it's crazy though, if you think about it, isn't it?
25:44
SPEAKER_01: Because we're just talking about taking the sediment that accumulated and passing it through.
25:50
SPEAKER_01: But the thing is, is that we have to catch up.
25:52
SPEAKER_01: If it was just a matter of, hey, let's pass the sediment on through, that would be like to me a common sense thing that would be really hard to get around, but we do have to catch up.
26:02
SPEAKER_01: So, anyway, the bottom line is then is that to remove this sediment and to pass it and to mobilize it through the dam, it does require a federal permit.
26:11
SPEAKER_02: And there's some good reasons.
26:13
SPEAKER_02: That that's a fact that actually kind of surprised me, to be honest.
26:16
SPEAKER_02: Like even a little dam somewhere in Michigan or Pennsylvania or wherever, you know, that you require a federal permit to actually discharge sediment from the reservoir downstream, that kind of surprised me.
26:26
SPEAKER_02: But there's some good reasons because actually, you know, sediment can be a pollutant if the sediment itself is polluted, right?
26:34
SPEAKER_02: And there's a couple of really famous examples of this.
26:36
SPEAKER_02: One is the Milltown Dam on the Clark Fork River in southwestern Montana.
26:41
SPEAKER_02: That was deemed a super fun site because there's just tons of sediment that was contaminated by arsenic.
26:48
SPEAKER_02: And when the dam was like threatened because I muted her.
26:55
SPEAKER_01: Now she's she's on now.
26:56
SPEAKER_00: So he stole my bear.
26:59
SPEAKER_00: So for that, it is a sad day.
27:03
SPEAKER_02: We're working here.
27:04
SPEAKER_02: We need a men working sign.
27:06
SPEAKER_00: Super sad.
27:07
SPEAKER_02: Yeah.
27:07
SPEAKER_00: I know.
27:08
SPEAKER_00: I'll be right back.
27:09
SPEAKER_00: Just give let me have that one, and then you get yourself a different one.
27:12
SPEAKER_00: That way you don't have to come back down again.
27:14
SPEAKER_00: We're recording.
27:16
SPEAKER_02: Jenny, we gotta get this done.
27:18
SPEAKER_02: Go away.
27:18
SPEAKER_02: Yeah.
27:19
SPEAKER_02: She's gone.
27:22
SPEAKER_02: Uh yeah, so so this was uh deemed a super fun site because there's loads of sediment that was contaminated by arsenic.
27:29
SPEAKER_02: And you know, the dam was threatened.
27:31
SPEAKER_02: They had to release a bunch of water that released a bunch of sediment that was contaminated, and so you know, created this huge catastrophe, environmental catastrophe downstream.
27:40
SPEAKER_02: There's another one, another example that's the Fort Edwards Dam on the Hudson River, where a lot of sediment that was contaminated with PCBs was released downstream, and it you know required a whole bunch of remediation to deal with this problem.
27:54
SPEAKER_01: How is it getting contaminated though?
27:56
SPEAKER_01: Is it from runoff then is getting impounded in the dam?
28:01
SPEAKER_01: Is that what the case is?
28:02
SPEAKER_02: What's I mean, most of these are old dams that were built, you know, back in the day where they were contaminated by either, you know, in one case, copper mining industry, another case, industrial city near the reservoir on the river that was just putting pollutants into the sediment.
28:15
SPEAKER_02: However, it happened.
28:16
SPEAKER_02: The fact is that the sediment that has built up in the reservoir is contaminated.
28:21
SPEAKER_02: So actually, you can't just release that downstream.
28:25
SPEAKER_02: Uh and so in that case, the sediment isn't the contaminant, but there is contamination within the sediment itself.
28:31
SPEAKER_02: So in some cases, that can be disastrous, but in other cases not.
28:35
SPEAKER_01: It's interesting though that regarding permitting, it permitting actually is not required as long as the sediment that you're going to mobilize and pass through the dam is equal to or less than the sediment load that is carried by the river.
28:50
SPEAKER_02: Yes, that's right.
28:52
SPEAKER_01: So if we could do this, then we could basically halt the sediment accumulation at all dams right now at the average of 25% less capacity, right?
29:04
SPEAKER_02: That's right.
29:04
SPEAKER_02: So this is the steady state.
29:06
SPEAKER_02: You can basically maintain things at a steady state, just have a pass-through of sediment through the dam itself, which is a pretty good solution.
29:13
SPEAKER_02: It doesn't solve the problem, but it prevents it from getting worse.
29:17
SPEAKER_01: Right.
29:18
SPEAKER_01: So there's another recommendation of doing these kind of controlled releases, allowing the dams to catch up that would use what we now know about fluvial geomorphology.
29:30
SPEAKER_01: A lot of the dams are aging, as we talked about in our previous episode.
29:33
SPEAKER_01: So a lot of these permits are a result of a lack of knowledge, too.
29:37
SPEAKER_01: You know, if we use what we now know about fluvial geomorphology, but what we know about rivers, we can do this in a smart way.
29:45
SPEAKER_01: But the permitting process is really hard to get around.
29:48
SPEAKER_01: And so the recommendation is really like we need to revamp the permitting and allow for local permits, not these federal, you know, all across the board permits.
29:58
SPEAKER_02: That's right.
29:59
SPEAKER_02: That's right.
29:59
SPEAKER_02: Uh the science has gotten a lot better.
30:01
SPEAKER_02: And, you know, we can do things like release more sediment during certain seasons where there's less impact on downstream wildlife, you know, and things like that that are actually quite clever and we know a lot more about the problem so we can solve it more easily.
30:14
SPEAKER_02: That's like the our take on the dam's impact on the river system itself.
30:20
SPEAKER_02: But as part of the follow-up here to our dams episode, we have a couple more points to make.
30:24
SPEAKER_02: And one of them is that we received a really good listener question via Instagram, and we love these questions.
30:30
SPEAKER_02: So keep hitting us up with questions.
30:32
SPEAKER_02: We love that.
30:33
SPEAKER_02: The question was regarding methane released from the reservoirs behind dams and whether this had a significant impact on climate.
30:40
SPEAKER_02: And actually, this is a really good point that we kind of skimmed over in our previous episode.
30:44
SPEAKER_02: So, Chris, you want to take a take a whack at this one?
30:47
SPEAKER_01: So, yeah, this is based on a paper that was published in 2016.
30:52
SPEAKER_01: And so this research studied the culpability of dams for adding greenhouse gases, which is you think about this and you're like, wait a minute, what how how would this like how would dams add greenhouse gases to the atmosphere?
31:10
SPEAKER_01: Well, it it actually is a substantial thing.
31:14
SPEAKER_02: Yeah, so this is potentially a big contributor to greenhouse gases, or relatively big.
31:20
SPEAKER_02: Uh, they can add a billion tons of annual carbon dioxide equivalents.
31:25
SPEAKER_02: That billion tons would contribute to about 1.3% of the global total uh as of 2016 numbers, so a little bit less than that today.
31:33
SPEAKER_02: But um, this is a significant amount, right?
31:36
SPEAKER_02: This is something worth considering, and this is actually added in the form of methane.
31:40
SPEAKER_02: So, Chris, let's go through a little brief thing of how this works.
31:42
SPEAKER_02: How do reservoirs add methane to the atmosphere?
31:45
SPEAKER_01: The lake that you get when you impound this water, that lake drowns and kills the ecosystem that existed there prior to that, right?
31:54
SPEAKER_01: So bacteria in the water, then, they feed on this organic material, right?
32:00
SPEAKER_01: Whether it was a forest that got flooded, the forest floor, whatever, that organic material that existed there, um, the organic material feeds on that and releases both carbon dioxide and methane.
32:12
SPEAKER_01: Now, this is interesting though, that like if the water is oxygen rich, the bacteria will release carbon dioxide.
32:20
SPEAKER_01: But if the water is oxygen poor, the bacteria will release methane.
32:25
SPEAKER_01: And the methane is really what takes over usually because what happens is these lakes, you get the runoff that brings in these phosphates and nitrates from fertilizers, right, from agricultural land use.
32:39
SPEAKER_01: And those fertilizers, they provide food for the bacteria.
32:44
SPEAKER_01: So these the bacteria just explode, right?
32:47
SPEAKER_01: And this bloom they consume all the oxygen, and so now you're dealing with an oxygen-poor environment, and so they burp out and fart out methane then from as they're decomposing.
33:02
SPEAKER_02: That's a good one.
33:03
SPEAKER_02: A whole bunch of bacteria farting out methane from the reservoirs.
33:06
SPEAKER_02: But you're right, it's a huge problem.
33:08
SPEAKER_02: And there's actually it's a big enough problem and actually a potential source of energy.
33:12
SPEAKER_02: There have been proposals that suggest that we could actually capture some of this methane and use it for fuel because methane is basically natural gas, what some people burn in our in our homes.
33:22
SPEAKER_02: And there are membranes that can separate methane from water, and there are actually microbes that do the same thing, basically this decomposition in reverse that will capture the methane and do this kind of really amazing stuff that might not be a transformative energy source, but it might help, you know, alleviate the problem of methane into the atmosphere.
33:42
SPEAKER_01: We do that with landfills.
33:43
SPEAKER_01: Right.
33:44
SPEAKER_01: You know, landfills have natural gas, you know, being emitted all the time, and they either flare it off, they burn the methane, or they capture it and and use it for home heat and power and things like that.
33:55
SPEAKER_02: Yeah, exactly.
33:56
SPEAKER_02: Okay, so reservoirs, methane, all super cool stuff.
34:01
SPEAKER_02: Now, Chris, you've been over there just being very impatient.
34:06
SPEAKER_02: You might sound patient on the podcast, but you've been pretty impatient.
34:09
SPEAKER_02: And you're itching to talk about this next section, I can tell.
34:13
SPEAKER_02: So that's because you didn't let me do it last time.
34:15
SPEAKER_02: I know, I know, I know.
34:17
SPEAKER_01: We yeah, yeah.
34:18
SPEAKER_01: Whatever.
34:19
SPEAKER_02: Well, that's water under the bridge, as they'll say, or over the dam in this episode.
34:23
SPEAKER_02: Over the dam, I'm just dun, dun, dun.
34:24
SPEAKER_02: But let's get to it because this is a really cool part.
34:28
SPEAKER_02: And so I'm gonna let you go and listener, you know, pay attention-ish.
34:32
SPEAKER_02: And if you get a little bit bored because Chris is rambling, that's okay, but make sure you come back when I come back on in like five minutes or something.
34:39
SPEAKER_02: Wow.
34:39
SPEAKER_02: Wow.
34:40
SPEAKER_02: All right, the Aswan High Dam.
34:41
SPEAKER_01: Chris, let's talk about it.
34:42
SPEAKER_01: Really cool.
34:43
SPEAKER_01: Yeah, I want to talk about this because the Aswan High Dam is widely considered to be at the center of this damn debates and issues that we've been talking about these last two episodes.
34:54
SPEAKER_01: So, a little bit of background.
34:55
SPEAKER_01: It's built on the Nile River in Egypt, and it was completed in 1970.
34:59
SPEAKER_01: It was built for several reasons.
35:01
SPEAKER_01: It was built for hydroelectric power, it was built to control the annual flooding on the Nile, which is the first time in human history that the Nile has been controlled like this.
35:10
SPEAKER_01: And most importantly, it was built for irrigation.
35:12
SPEAKER_01: And so it has a lot of advantages.
35:15
SPEAKER_01: You know, it does.
35:16
SPEAKER_01: It's not at all a downside store to this.
35:18
SPEAKER_01: So the advantages are it allowed for irrigation even during their significant drought season.
35:25
SPEAKER_01: We're talking about Egypt, right?
35:26
SPEAKER_01: So they have a significant drought.
35:29
SPEAKER_01: Two, the dam generates a massive amount of electricity.
35:34
SPEAKER_01: It is capable of generating 45% of Egypt's electric needs.
35:41
SPEAKER_02: And this is relatively carbon cheap electricity, too.
35:45
SPEAKER_02: Hydroelectric power over the lifetime of the dam is pretty cheap in regards to carbon emissions.
35:51
SPEAKER_01: Yeah, for sure.
35:53
SPEAKER_01: Thirdly, flood mitigation.
35:56
SPEAKER_01: The dam has undoubtedly saved lives.
35:59
SPEAKER_01: Nobody argues that.
36:01
SPEAKER_01: And then lastly, it's a major tourist attraction.
36:04
SPEAKER_01: But what are the disadvantages?
36:05
SPEAKER_01: What's this controversy that surrounds this dam and why is this at the center of the debate?
36:10
SPEAKER_01: Well, a number of things.
36:12
SPEAKER_01: Okay.
36:13
SPEAKER_01: One, and this is like in no particular order, I'm just going.
36:16
SPEAKER_01: Okay.
36:16
SPEAKER_02: Yeah.
36:17
SPEAKER_01: Over a hundred thousand rural Egyptians were displaced.
36:21
SPEAKER_01: Next, they did not account for the massive rates of evaporation that would take place.
36:28
SPEAKER_01: Over 10% of the water in the lake is lost due to evaporation.
36:32
SPEAKER_01: I mean, remember, it's in Egypt.
36:34
SPEAKER_01: It's kind of hot.
36:35
SPEAKER_02: It's kind of a funny thing to not account for as an engineer.
36:40
SPEAKER_01: It gets better.
36:40
SPEAKER_01: It gets better.
36:41
SPEAKER_02: But I guess this was in the 1960s when they were designing this.
36:44
SPEAKER_02: So maybe we'll give a little bit of credit, but still, anyways.
36:48
SPEAKER_01: Okay.
36:48
SPEAKER_01: All right.
36:49
SPEAKER_01: So next, and this is this rings home, a massive accumulation of sediment, which has largely been ignored.
36:57
SPEAKER_01: So they're not doing anything for the sediment, which is basically the issue of this podcast.
37:01
SPEAKER_01: Next, erosion downstream.
37:04
SPEAKER_01: Get this has destroyed bridges and other dams.
37:09
SPEAKER_01: So this hungry water at a cost that is greater than the cost to build the dam.
37:16
SPEAKER_02: That is an astonishing thing.
37:18
SPEAKER_02: And so the way to picture this is picture driving over a dam.
37:21
SPEAKER_02: You have the big pilings going into the water.
37:23
SPEAKER_02: Now, if that water is hungry, it's just going to erode those pilings faster because it's hungry water.
37:29
SPEAKER_02: And so this is what the destruction is because the water is hungrier than its natural state when those bridges and other dams were made.
37:37
SPEAKER_02: So that's what's going on.
37:38
SPEAKER_01: The Nile Delta is disappearing.
37:41
SPEAKER_02: Bummer.
37:42
SPEAKER_02: That sucks.
37:43
SPEAKER_01: A bummer.
37:44
SPEAKER_01: Did you just say bummer?
37:45
SPEAKER_02: Yeah.
37:46
SPEAKER_02: That is the under understatement of the century.
37:49
SPEAKER_01: You just understated that is so bad.
37:56
SPEAKER_01: You're just not a very good partner.
37:58
SPEAKER_01: Um so the sediment that used to get to the Delta is trapped in Lake Nasser.
38:06
SPEAKER_01: It's this sediment accumulation.
38:08
SPEAKER_01: Next, they now have to fertilize their farmland, their agriculture, because the Nile used to flood.
38:16
SPEAKER_01: And the flooding in geology, we call that the gift of the river, which is sediment.
38:21
SPEAKER_01: Okay, so it would, as the river floods, it would disperse this very fine-grained sediment over the floodplain, and that that very fine-grained sediment quickly breaks down into very fertile soil.
38:32
SPEAKER_01: And so now they have to fertilize it.
38:35
SPEAKER_01: Next, and this one gets me.
38:37
SPEAKER_01: The dam was built on porous and permeable sandstone and has about half of the water that they expected.
38:47
SPEAKER_01: Okay, the reservoir has about half the water they expected to get because they're losing water to the groundwater, to the water table below.
38:55
SPEAKER_01: Okay.
38:56
SPEAKER_02: Again, poor engineering 50 years ago.
38:59
SPEAKER_01: So I'm gonna finish with this one, and it's so important and tragic at the same time.
39:04
SPEAKER_01: So because they irrigate now, because that was the major reason why they built the dam for irrigation, okay.
39:13
SPEAKER_01: There's no drying period of the land.
39:15
SPEAKER_01: Okay.
39:16
SPEAKER_01: And so it's produced a habitat for snails that carry this parasite, which is uh it's this parasite that causes urinary tract and intestinal infections.
39:26
SPEAKER_01: Now, they before the dam, though, the snails were kept in check because they had a dry season and they don't have that anymore because they're irrigating year-round.
39:37
SPEAKER_02: I mean, that is an interesting one, and that strikes particularly close to home because my family, meaning my father and my sister, work on this schistosomiasis thing.
39:47
SPEAKER_02: Well, they work on the North American analog for schistosomiasis.
39:51
SPEAKER_02: So, you know, this snail infection thing is kind of well, near and dear to my heart in a way.
39:57
SPEAKER_02: My biologist's family likes this stuff.
39:59
SPEAKER_02: But for me, it really highlights the difficulty or the interesting importance of dams because, you know, last episode, the Spartan episode, we talked about the river system and how when the river is actually filling in stuff in the delta, that's a sign of a healthy river system.
40:15
SPEAKER_02: And here we're just basically the Aswan High Dam is providing 45% of Egypt's energy needs in a carbon cheap way, but it also is creating all of these problems that some of them were predicted, some of them weren't predicted.
40:32
SPEAKER_02: So it's part of the conversation of just be informed when you're thinking about the pros and the cons of these really complicated issues.
40:39
SPEAKER_02: Just be informed, right?
40:40
SPEAKER_02: And and thinking and understanding about how dams provide benefit and also have some disadvantages is a really important thing to consider if you're thinking about removing or installing a dam in your area.
40:53
SPEAKER_02: Um, and so it's a it's a really interesting focal point here.
40:56
SPEAKER_02: So, Chris, I'm glad you had the rant.
40:58
SPEAKER_02: I'm glad you brought it up because it really highlights how important these things can be.
41:03
SPEAKER_01: Yeah, when you change a river, you're gonna have consequences, right?
41:06
SPEAKER_01: And some of those are intended consequences, and some of them are gonna be unintended consequences.
41:11
SPEAKER_01: You're changing habitats and ecosystems and uh geomorphology.
41:16
SPEAKER_01: It's just uh it's you know, it's just interesting to think about these things, right?
41:22
SPEAKER_02: Well, I'm glad that we really revisited this damn topic.
41:26
SPEAKER_02: Although it took a little bit of work on your part to get me on board the first go-round.
41:29
SPEAKER_02: It's really important and it really highlights key concepts from the basics of streams, from riffles, runs, pools, and glides to you know our energy transition and habitats of like beautiful trout.
41:42
SPEAKER_02: I mean, it brings in so many important topics all in one spot, and it's really fun to think about.
41:48
SPEAKER_02: So uh with that, I think we're gonna wrap it up here.
41:51
SPEAKER_02: And as usual, if you like what you're listening to, we just ask that you share it with somebody.
41:55
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42:03
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42:07
SPEAKER_02: Those things really matter to the podcast and to us, and we would appreciate it.
42:12
SPEAKER_01: Absolutely.
42:13
SPEAKER_01: Hey, we'll see you next week.
42:14
SPEAKER_02: All right, take care, everybody.