A trip down the River Cam

You're invited aboard the Princess Charlotte on the River Cam for a Naked Scientists Summer Special
26 July 2022
Presented by Harrison Lewis, James Tytko
Production by Harrison Lewis.




Harry Lewis and James Tytko are off on a summer science special, a jolly down the River Cam with their Captain for the day Peter of Camboats. If you're willing to adhere to the safety rules of the vessel you'll be making pit stops to check out the local wildlife, sporting prowess of the University's rowing team, historical engineering works that still function perfectly and local residents taking it upon themselves to monitor the health of the water itself. But to kick it all off the boys will start by dipping their toes in the deep end, and making the most of what's on their doorstep...

In this episode

A swimmer in the sea.

00:00 - Wild swimming

River swimming clubs are at capacity; is no one worried about the cleanliness of the river?

Wild swimming
Simon Crowhurst, Nicky Blanning, Alex Buxton

Harry Lewis and James Tytko prepare for a dip in the River Cam, Cambridge. Down a quiet strip for the river, trees overhang the water and the occasional punter drifts downstream. They are joined by Simon Crowhurst, Nicky Blanning and Alex Buxton...

Harry - That was quite impressive, James. Are you gonna take the stairs?

James - The slow way in?

Harry - I think there was really quite a stark difference between the way you got in, James, compared to Nicky, Alex, and Simon.

James - Definitely. How long until I acclimatise?

Simon - well, you need to move, give it a minute.

James - Okay. I'm good.

Harry - You're listening to The Naked Scientists and it's our summer special. So that's with me, Harry Lewis, and I've managed to drag James Tytko out the office too. Is it a hot one where you are at the moment? Because it certainly feels like it has been here over the past few days and, to beat the heat before the show kicks off properly. It looks like James and I are gonna get lured in for a wild dip in the river cam in Cambridge.James and I are joined by Nicky Blanning, gliding effortlessly through the water alongside Alex Baxton, and here on the banks with me is Simon Crowhurst. Coming down on such a beautiful day, where are we and what are we looking at?

Simon - We're on Sheep's Green. We're looking at the river Cam banked with beautiful willows. So I can see my wife and my friend, Nick, in the water swimming along and enjoying the water, which at 21 degrees is warmer than it usually is during the year. Wild swimming has increased in popularity immensely over the last few years and we've got so many applicants to join our swimming club that we can't cope with the numbers.

Harry - And you said it was 21 degrees, which sounds actually quite warm. I'm quaking in my boots about getting in Simon, because I hate the cold, but 21? How can you prove that that's 21 degrees? Well,Simon We've got a thermometer in there so we can take a look at the actual measurement. Let's do that.

Simon - So here we are with an old fashioned analog thermometer. We'll take it quickly to the water before it has chance to change. It's just under 21 degrees and you can see the liquid falling immediately as it comes out of the water because it's cooling down in the air, working a bit like a fridge.

Harry - <laugh> James, you just jumped out of the water as well. A valiant effort, I thought, when you got in. How was it?

James - Yeah, it's definitely a cliche but it's lovely once you're in.

Harry - Simon, you said that at the moment your particular swimming club's literally just got too many applicants to be able to support. Do you think that's representative of the rest of the rivers and wild swimming clubs around the UK?

Simon - Well, there's been a tremendous surge in interest and activity of wild swimming. As long as people do it safely and responsibly. I don't think it's a problem. Where people just charge into the water without any experience -without being strong swimmers - then you can have problems and people can get into difficulty very quickly.

Harry - Nicky and Alex you've swam over to us graciously, I might add. There wasn't quite the calamity of when James got in and he was holding his breath as hard as possible. <laugh> What's it like? How's the river?

Nicky - Oh, it's really beautiful. Honestly, it's absolutely gorgeous. I could stay at it for hours.

Harry - Well, I know for a fact, Nicky, you've actually been out twice today. Now you were up this morning, weren't you?

Nicky - I was, yes. I swam in the Lido and I try and swim twice a day at the moment in the summer while it's so nice.

Harry - I mean, there are health benefits that are supposedly associated with getting yourself in cold water. Obviously ,exercise is good. You're in nature, so it's a little perk for your mental health, isn't it? Are these things you think about or is it just the fact that, you know, I've got a bit of extra energy and I'm up nice and early. Why not get out there and into the world?

Alex - It becomes an addiction. I think Nicky would probably agree with this, an addiction. It's like your daily fix of something that's you know, it's a good addiction to have, I hasten to add.

Simon - It's one that has a positive effect on your physical and your mental health. I find it punctuates the day really well when I've been for a swim, it almost doubles the enjoyment that you get out of the day

Harry - On a day like today, it makes complete sense to make use of it, seeing as it's on the doorstep. Are you guys coming out here when it's not warm and sunny, when it's not 21 degrees in the river?

Nicky - Yes. I think the coldest I've swam has been actually when the river's been frozen and I've cut a circle in the ice and swam round in a circle.

Harry - You can't see it, but I'm astonished. Nicky, was this witnessed by anybody?

Nicky - Yes I have photographs.

Alex - We waded through snow to get to the river and you can't even see the edge of it

Nicky - We waded through floods of water!

Alex - That's what I mean by an addiction.

Harry - And as well, this is based on swimming that's been done here historically. Isn't it? There's photos of this exact area. Taken en mass.

Alex - Before indoor pools were built, before that, everybody swam in the river. My mother was brought up in Cambridge and she learned to swim in the side river here in the 1930s. You had to swim as a child. You had to show you could swim in the shallow side river before you were allowed in the main river, and there were people actually in charge of all this.

Harry - Well, that's probably changed quite a lot today. There isn't really a body or governing body that does look after swimmers in wild rivers is there? And Imean, that brings me onto, I guess, a more general question. It's not quite the picturesque clear colorless water of the Maldives. There is a dark kind of murky green isn't it, the river Cam? <Laugh>. So do you feel safe when you get in and out? Is there any worry about the cleanliness of the water?

Simon - Yes. There are concerns about the water quality and we are downstream of water treatment plants. The water quality does vary. There are people who heroically monitor the water quality through the year. We know there are times when the bacterial load is higher. Some of that is due to release from sewage works. Some of that is due to more suspension of particles in the water when the river flow is higher and it's hard to separate out those two effects.

Harry - And how do you feel, Nicky? Is there any fear when you get in or...

Nicky - I certainly think about it more when it's flooded and there's been heavy rainfall. I think you have to be more sensible then and I tend to keep my head out of the water. It doesn't stop me swimming, but I do think about that.

Harry - Right. Well saying that I think I put it off long enough now. I better get in as well.

Harry - Go on then. Before I dip my toe in the water, let me catch you up to speed. So, the plan is that we are going on a river trip down the river Cam right into the heart of Cambridge. We'll be stopping at sites of scientific importance on the way. So hopefully we'll also get a chance to leaf through a couple of history books, too. Sport, wildlife technology, all to come. But first we better meet captain Peter, which we'll do straight after this. God, it's gonna be so cold.

James - Don't build it up. Okay. <Splashes>

Water vole

07:13 - Protecting chalk rivers

200 chalk rivers are known globally, 85% reside in Southern and Eastern England...

Protecting chalk rivers
Iain Webb, The Wildlife Trust

The team poddle down the River Cam to their first stop on the trip. Captain Peter tells the Naked Scientists of J. R. R. Tolkien's favourite pub in Cambridge, The Green Dragon. Supposedly, the freehold makes its own apperance in the novel and iconic films too. Iain Webb, Community Communication Officer at The Wildlife Trust Cambridge, has the boat steered over to a quiet river mouth entering the Cam. Iain and colleagues are putting in efforts to protect the rare chalk rivers and wildlife they harbour...

James - Well, I'm not sure how you've wangled this, Harry. I can see we're approaching our vessel here. It looks pretty plush.

Harry - It does look pretty plush, the 'Princess Charlotte'.

James - The Princess Charlotte of 'Eco Cam Trips'. And we're about to be introduced to our skipper, Pete, and Ian Webb from Cambridgeshire Wildlife Trust.

Harry - Well, let's go say hello, shall we?

James - Hello, Peter.

Peter - Good morning.

James - Nice to meet you. Thanks for having us on your boat.

Peter - It's a pleasure.

Harry - Morning, Peter. And what a vessel as well.

Peter - Yeah. The Princess Charlotte is a lovely eco boat powered by solar panels on the roof and what a better day to get it out and about on the river with you.

James - Absolutely. So that's where the 'eco' in Eco Cam Trips comes from.

Peter - Yes. Yeah. Absolutely. We're trying to do our bit for the environment and especially with Ian here today, need to make sure that everything's done properly in a clean way that preserves the wildlife and the integrity of the river.

James - Well, that segues us on very nicely to Ian. Nice to meet you, Ian.

Ian - Nice to meet you.

James - And what might we see today?

Ian - Well, who knows? It's always an adventure going on the river because you never know what you're gonna see. But, you know, Moorhens, ducks, swans, the usual fair. But, we might see a kingfisher; might see a grass snake swimming along the edge; water voles; maybe we've got some dragonflies or damselflies; fish leaping out the water. But it's always wonderful being on the river and it's always a surprise, what we're gonna see.

James - I'm chuffed, I'm really excited. Pete, are we ready?

Peter - We are, yeah, we'll cast off in a moment if you'd like to get yourselves on board.

James- Thank you very much.

Peter - All right, gentlemen, here we go. As you can hear the boat is lovely and quiet. Just a little hum from the electric motor.

Harry - And there we go. It's official, we've weighed anchor. We've been out this morning, James and I, in the water ourselves. And obviously we're sort of preserving that by, on our trip today, being on your electric boat, as you've said. I mean, do you see many of these actually on the water and what's going on? What's this bit of tech, is it half decent?

Peter - Yeah. we believe it to be a unique boat in the UK. It's an electric catamaran and then we converted it to solar panels in the last couple of years. So yeah, we think it's a very special boat because it doesn't use any fossil fuels, it's virtually silent and, at the end of the boat's life, the boat's built of aluminium and it can be recycled completely itself. We'll quite happily power the boat all day, top the batteries up as well, and that would give us about four or five hours of evening cruising, even when the sunlight disappeared.

Harry - How much power do you need to get this thing going?

Peter - Currently, we are using about one kilowatt and the solar panels are generating about two and a half kilowatt.

Harry - Oh, fantastic. And for the rest of the day, where are we off to? What's this journey gonna look like?

Peter - Well, we started off at our main moorings at The Plough at Fen Ditton, just on the Northern edge of Cambridge and we're currently traveling upstream in towards the city center. We're just coming around Ditton corner and, if you draw an imaginary line across the river, this is the city boundary. So we're leaving, Fen Ditton behind and here is Cambridge in front of us, but it doesn't look like it because there's cows in the meadow, there's ducks and ducklings directly in front of us, there's people wandering around. This could be somewhere out in the East Anglian Fens, not a mile and a half from the city center. Looking over the side of the river, the water looks quite clear and you can see down towards the river bed, but that is a slight problem that the river's not flowing that much at the moment. When we get down to Jesus Lock in town, you'll see that the weir is hardly flowing at all. That means the river is stationary and there's lots of weeds growing up through the river, which is good in some ways, but it does make navigation a bit tricky sometimes. During the winter, it's a completely different story. The river turns brown with all the sediment that gets washed out from the fields. And, at that stage, the river's flowing very fast. We're currently about three or four inches below the normal river level because it's not being topped up with fresh water all the time.

James - So Ian, following on from what Harry was talking about with Pete, the stillness of the water is one of the things that strikes us as we are gliding down it. What can we take from how that will impact the environment?

Ian - So yeah, the lack of rainfall we've had this spring has really had an impact on the flow of the fresh water into the river. That impacts on not just the quality of the water, as Pete mentioned, it's really quite still, there's not much flow going on. The fresh, regular fresh water from showers and storms, et cetera, throughout the year helps dilute any pollutants that are found in the water and the, runoff from farming, which inadvertently happens. Oh, sorry, it's just a grey heron just heading our way.

James - Oh, amazing. That's coming right for us.

Ian - It is. It's gonna go through the middle. <laugh> Nearly.

James - That is beautiful.

Ian - Very nice. And with the lack of flow means the build up of water plants. We can see there's curled pondweed in there. I saw some water milfoil all growing in the bed of the channel, which is great, but when there's a low flow, it really does get quite thick and can clog up the river. And it's not just the lack of rainfall in the spring that's the issue, it's the over abstraction of water. So yeah, a lot of the river Cam water comes from chalk streams of which England has an international responsibility. It's a very scarce habitat in the globe. We'll be seeing one in a bit actually along Stourbridge Common, those water bodies are fed by chalk water that rises from the chalk aquifers that are beneath South Cambridgeshire, which is quite a unique habitat. The aquifer, you know what an aquifer is, is a sort of subterranean reservoir of water that is charged by rainfall.

Ian - So when the rain falls on the ground, some of it runs off into rivers and streams et cetera, but a lot of it percolates into the ground and it sort of collects in a big underground reservoir in the chalk. At certain points, at a certain level where the chalk surface is broken, that water bubbles up - it 'spring heads'. So there's quite a few in south Cambridge, 'Nine Wells' just south of Cambridge is a good example. Where we'll be looking at Coldham's Brook that rises in Cherry Kinton, which is in Cambridge as well. So that water flows from those spring heads and, as all water does want to do, goes downhill. So eventually it created these habitats, these streams, these water features that are really quite unique and, because of the nature of the water, it being very clean because there's very little pollutants, it has come straight from the ground, it's a very constant temperature as well, about 10 degrees throughout the year.

Ian - It has created quite a unique habitat. Some of the features have been lost over the years of over-engineering, over -dredging of these chalk streams. So one of the major features is graveled bottomed chalk streams. Nice, not very deep and quite wide, providing great habitat for aquatic plants, such as 'water crowfoots', which in turn provide really good habitat for lots of invertebrates, which in turn provides food for fish, brown trout are a good example of a species found in chalk streams. And from that, if you talk about food webs from a good, healthy base of plant life, you get a very complex and very diverse and very secure food web going all the way up to otters. And we have otters coming through the city all the time.

James - I find that amazing that the temperature of the water stays so consistent all year round.

Ian - Because it's coming straight from the ground and it's been, obviously now there's lots of water coming off roads and the arable land et cetera. It is sped up, you know, the actions of people draining the land, et cetera, building lots of houses causing lots of hard services means the water flows off very quickly. It doesn't have time to percolate in and that's why you have issues with flooding with lots of hard impermeable land. When it rains in something, as we have more experience of stochastic rainfalls, a really heavy downpour, that water's got nowhere to go. So it just flows into the drains and flows into the rivers. And that causes either localized flooding, if the drainage isn't sufficient to remove that water, or it causes flooding in the river when all the water joins and sort of adds to what's already there. We're getting to where Coldham's Brook, a chalk stream, now enters the Cam on the edge of Stourbridge Common.

Harry - It's quite picturesque, isn't it?

Ian - It is very nice. Nature is wonderful when it gets an opportunity to show off itself.

Harry - What have we got there on the riverbank? There's a bit of pink sprouting out and there's draping green.

Ian - I can see branched bur-reed. You've got a greater willow herb. You've got a moorhen chick sitting on the rock. You've got some water mint. There's some gypsy wort.

Harry - I know you said that these types of habitat are quite rare and England has a real duty to protect them. Firstly, what do they bring about that we need to protect? And secondly, are you working with the wildlife trust to help look after them?

Ian - There's about 200 chalk streams or chalk fed streams and rivers in the world. And we have about 85% of them in England. So, as a habitat, which is really quite special, it is really quite rich for invertebrate and plant life and is indicative of good quality habitat. We have a great responsibility to make sure we're looking after it as well as we can. And that is difficult because yes, we can change the sort of physical nature of these streams and rivers. But it's the amount and the quality of the water that is key that makes the habitat so special. And that is a lot harder to manage. My colleague Ruth Hawksley is an amazingly active person working to enhance these chalk streams, and where possible engaging with the landowner, to introduce features that would've been present in a natural chalk stream, but have been lost due to overengineering. So putting in gravel beds, putting in more meandering, The nature of how rivers and streams have been managed over the years is to get rid of the water as quickly as possible, powering water mills, et cetera.

Harry - And agriculture, I suppose as well.

Ian - Oh yeah. Wanting to drain the land so we can grow food to feed our population, which is an important thing to do.

Harry - And so Ruth's just putting some of these features back in, like you said. Meanders, gravel pits, what else is she doing?

Ian - She's putting in big lumps of wood, which is quite exciting, just to help the water move more within the channel, let it become more natural. And one of the issues with chalk streams is there isn't that much flow because they're spring fed. It's not like a raging torrent up in the Yorkshire Dales or something with a large amount of energy in the water to do a lot of movement of gravels, et cetera. These rivers are quite gentle. And so once a feature is lost, it's very difficult for that volume of water to actually make an effect. That's why we have to introduce these gravels, because a lot of the gravels would have been scooped out when they were straightened or deepened to allow the passage of water to be quicker, et cetera.

Harry - And as Peter now pootles us away from Coldham's Brook, are there any particular success stories from the local area where Ruth's gone in and changed the dynamic flow of the river?

Ian - There's this work starting to look at Coldham's Brook. Hobson's Conduit is another one. And outside of the city, there's Hoffer Brook, there's Mel river. There's actually places within the river Cam itself where these features being put in. And also one of the things working with mentioning other organizations is partnership work, working to help remove barriers within the rivers and streams, that hinder migration of fish. So weirs to control water flow, et cetera, or if they can't be removed, putting in features to allow fish to pass through. So if you go to Byron's pool in south Cambridge, there's a bypass channel, which bypasses, as they suggests, the weir at Byron's pool, but allows fish to migrate upstream.

Harry - What fish are we talking?

Ian - Oh, there's about 18 species of fish.

Harry - Here in the river Cam?

Ian - Yeah. They're all under the water, you see, that's the thing. You can't really see them. It's a challenge. So with a lot of the things, looking at the health of rivers.

Harry - And what are a few of those?

Ian - Eel, brown trout, pike, perch, dace, rudd, chub, pike. Yeah.

Harry - I think you've nearly got the whole 18.

Ian - Possibly <laugh>. Yeah. So there is a really rich fish fauna within the river, which is great, but it could be so much better and you just need to create those habitats within the river channel to allow them to find those places to live, but also making sure that water is there constantly flowing, clean and healthy.

Peter - So just to give you a description of where we are on the river at the moment, we've just come under the Green Dragon footbridge. It's proper name is the Stourbridge footbridge, but the Green Dragon pub is just at the end of the bridge. And as we come along this little stretch with all the liveaboard boats, just off in front of us, got a small herd of cattle. You were off the boat a little earlier on looking at Stourbridge Common. We're just coming to the tail end of it and Ian was talking about the cattle that come and graze the meadow. Well, here they are standing underneath one of the trees. There's a horse trough fed by the water point, just here. So the cattle come and have a drink here. So it's quite natural for people to come across them, just standing around milling around, not doing a lot. And off in front of us, the tall chimney of the old waterworks building, the old technology museum just here on Riverside.

Harry - And little does James know I've got a bit of a surprise for him because we're actually visiting that. So we'll be pulling in, in just a couple seconds.



20:40 - Historic sewage systems

In the 1800s cholera swept through Cambridge, until the installation of a state of the art steam engines...

Historic sewage systems
Jinx St Leger, Cambridge Museum of Technology

Rising up from the banks of the River Cam, is a tall chimney like structure, the tallest thing to emerge from the city's skyscape. The structure belongs to the Cambridge Museum of Technology. Jinx St Leger, the chief engineer, waits for Harry Lewis and James Tytko at the museum entrance... 

James - It's a special treat for us Jinx, this.

Jinx - Yes. Yeah. Well, you know, there's nobody else here.

James - So why is that? Why is it closed?

Jinx - The museum's actually only open at the weekends at the moment. We are really reliant on volunteers and we just don't have that many people that volunteer. So at the moment we are only open Saturdays and Sundays.

James - And can you tell me the Cambridge Museum of Technology - What's the story? Because this didn't look like it was originally built to be a museum.

Jinx - No, very much not. It was a very, very practical building. These two very beautiful engines, in this main engine hall, actually originally pumped sewage. So in the 1800's, there were several outbreaks of cholera in Cambridge because the Cam was an open sewer. So after several outbreaks of cholera, it was decided that they needed to treat the sewage somehow - get it out of the river. And this station was built to pump that sewage to Milton, where the sewage works still currently is, they're looking to move it, but it is still currently being treated in the same place it was over 120 years ago.

James - And could you talk me through what I'm looking at here? This is visually very impressive.

Jinx - Well, they're stationary steam engines. So we have two engines in here. These two, as far as we know are the only two left in the world and they both work. We also have around the room, some smaller engines that were originally used to pump water into the boiler from steam. So, originally, they would've pumped water from the river, but now we don't do that. We come from the mains and we then pump it that way.

James - If I were to come back another time, when might I be able to see these engines in action?

Jinx - So we have just got back into steam. We had our first steam event in many years in April because we'd had the boil refurb, so we couldn't produce steam before that. And then we had another one in June. We're looking to have another steam event in September.

James - But when you say a steam event -

Jinx - Oh, see, I'm using the terms of the community. So, a steam event is basically when the museum or any place that runs steam engines will raise steam, runs engines. And it's a bit of a family event really. And there is very much a steam community. So it's not just people running steam engines. We are like a small family and, and we work as a community together to do that. So the colloquialism is 'steam up'. So if you are a steamy, if you're in the steam community, you say we're having a steam up. <laugh>

James - I wonder if we could have a look at some of the components of these enormous engines.

Jinx - I'd like to show you this big wheel here. So, obviously there's one on each engine. So, when we run this, before we start the engine at a 'steam up', I will turn to the audience and say, "how do you think the steam engine works"? And pretty much 99 times out of a hundred, people will say that big wheel spins round. And it doesn't, because it's connected to a tiny beam. And actually that wheel only revolves 90 degrees. It rocks backwards and forwards. So we often say our engine is very beautiful, but not very dramatic. It's always kids that notice it. It's never grownups, grownups never notice that that doesn't spin. It's always the kids going well, there are two rods going through the floor.

James - So the engines that we can see right now, that's not everything that's going on here when the whole thing's operational.

Jinx - No, absolutely not. This is a very attractive tip of an iceberg. There are several floors below us. Some of them are now flooded with water.

James - Where next?

Jinx - I can show you through to the gas engine room.

James - Let's do that.

James - Okay. It looks kind of similar jinx to what's in the other room, but I'm sure it's, it's very different. What can you tell me about what I'm looking at right now?

Jinx - Right. So these are very different. These are gas engines. The problem with a steam engine is you can't just flick a switch and get it to go. It needs to be warmed through. It needs to sort of be prepared. It needs to also work under load. Not so with the gas engines, you can pretty much flick a switch on these and they will start working. They don't need to have a load on them. So as the size of Cambridge grew, there was more population, more sort of flash flooding because obviously the ground had been covered. So the ground and the water wasn't soaking away in the same way, and they needed more engines, and this was the ideal accompaniment to the steam engines, because basically you could flick a switch and off you go.

James - How much water did they need to move?

Jinx - Now that's a tough one. And obviously it depended on how much rain there'd been and how much sewage there was. So I can't really give you an exact answer off the top of my head, but it had to move three miles up a slight hill - as hilly as the Fens get - to the sewage pumping station. So it was quite an ask.

James - And what sort of effect did that have on the cholera outbreak?

Jinx - Well, just having the steam engines here basically stopped that because the Cam was no longer an open sewer. So, as soon as that was being dealt with, no more cholera. Wonderful.

James - Jinx, we've entered a bit of a cavernous expanse with bits of machine everywhere. What's going on in here?

Jinx - So this is the boiler house. So obviously you can't run steam engines without steam, and this is where the steam is generated. So it's a big old place. The biggest boiler is about the size, It's about the height of a house, and about half the width of a, sort of a fairly decent sized house. And we have two smaller boilers. The ceiling here is really, really high. It used to get extremely hot. So one of the reasons you would have tall ceilings is because of the heat in here as well. When the plant was working, the engine room would've been pristine. So nice, shiny ceramic tiles, very, very beautiful. Boilerhouse was very much the opposite. So you can tell it's dusty. You can tell that things were burnt in here. All the walls are kind of this off-white. It doesn't look run down, but it does look like it's the business end, it really does.

James - How does it work?

Jinx - All our boilers here are Babcock and Wilcox and that company has been going for a very, very long time. The boilers are all water tube boilers. So, inside the boilers, they have big tubes filled with water and you put fire under it and that creates a steam. Initially, fuel was pretty free. The council collected rubbish, the rubbish was sorted up that top area, which is called top bay. Anything with a high calorific value was burnt and other things could have been reused or recycled. Later on, the destructive boilers were adapted. When the calorific value of the rubbish went down, the fronts of the boilers were changed so they could be stoked with coal. And then the final, the grand lady of this area is boiler number four. So boiler number four was put in in 1923, so she's nearly a hundred years old. And she's really the reason that I ended up working at the museum.

James - Why is that?

Jinx - So I was a volunteer here for a while and they needed somebody to project manage the restoration of this historic boiler. She was in a bit of a bad state. The problem with industrial heritage is that when it's in its working life, it's constantly being used and maintained, and all those things that you do when you have a working plant. When you have something that then becomes static, it becomes prone to rust and decay because it's not being used all the time. She had basically failed at a steam up in 2014. Right in the middle of the steam up, some of her tubes bursts. The curator at the time, alongside with some of the trustees, applied for a heritage lottery grant and basically they needed somebody to run the project, to restore the boiler. So that's where I came into the museum.

James - What's the process of restoring something as complicated as this?

Jinx - Well, the thing is, it's not complicated. When I came here and I was talking to the subcontractors before we started work, they basically said ""oh, it's not complicated. It's a big kettle, which might be an oversimplification, but not by much. So, you're heating water, you're putting it into a drum and the steam's coming off the drum and powering the engines. But, unlike the boiler you might have at home, most of the walls of this boiler are made of brick. So the big complications we had to take the walls, one of the walls down before we could get inside to sort out the tubes that was complicated because we didn't know what was historic and what wasn't. Because this is a protected building, we had to establish how old the wall was. And then we found out it'd been rebuilt in the 1980's by the volunteers, so then it wasn't a problem anymore. We took the wall down, and we removed all the tubes. That sounds very easy, it took a long time, and then there were some innards that needed to be replaced. And then tubes went back in wall and went back up. The whole process took well over a year because we had to have different contractors on site at different points.

James - I'm desperate now to see the rest of that iceberg we talked about earlier.

Jinx - Well, Just because it's you guys, I can do that.

Harry - <laugh> Jinx, You're an angel <laugh>.

Harry - Through here?

Jinx - Yeah. Through here.

Harry - That's a slight on my sandals. Not really appropriate footwear for any engineering.

James - No, not for a place of work like this. Down the hatch. We've opened up a sort of cellar-type area. There's some ominous humming going on, emitting from it, and a sort of rusty looking ladder that we're about to climb down. I mean, after you, Harry.

Harry - It looks very traditional. That's what I will say Jinx.

Jinx - Yes. Yeah. It's not rusty and it's perfectly fine. But the ominous humming you can hear is the ventilation system, because this is a confined space. So, obviously we want to adhere to health and safety. So, even though this is a very old building, we've got modern engineering practice here. So we have it just to make sure the air's nice and fresh under the engines.

Harry - Oh, how slim are these people? Jinx? <Laugh>.

Jinx - Uhh, slimmer than you.

Harry - Yeah. Obviously. It really feels like the belly of the beast down here. Doesn't it? Yeah. What an absolute trip back in time, it feels like. Suddenly, we are surrounded by all these old components.

Jinx - So you've got two sets of pumps here. You've got what are called air pumps, and you have the actual main pumps that would be pumping the sewage. So, already where we are, it is a very high ceiling and there are several of those below us. Like I said before, a couple of them are actually flooded through. So this might look very unattractive and unappealing, but like with the beautiful engines at the top, we need to work on these. On the top of each section of the pump, we have these little yellow boxes, which you probably wouldn't notice, but every time we start the engines, we have to pour oil in there and we have wicks like you would have in a candle. And that helps the system all lubricate.

James - Wow.

Jinx - It's never ending. There's always something to do. Always something to prettify. I'm concerned, basically, with these engines in the main engine room, but there's a whole site with other things on it that need to be done. We also are looking to encourage more young people into engineering. So in the future, we're looking to have a program where young people can come and work alongside some of our volunteers and get some engineering experience as well. So I think that's one of the next big things and obviously steam ups.

James - We have to get ourselves down to the next one.

Harry - I will. Yeah. And what's fascinating is, later on, we've spoken about cholera and sewage in the Cam. Well, later on, we're speaking to Susanna and Anne as well, they're doing some real life time monitoring of the pathogens and bacteria that are in the river at the moment. So we are going literally from the history of the river Cam and sewage to the future. So, Jinx, thanks for grounding us in such good knowledge.

Jinx - Yeah, thanks for coming.

A 4 person boat rowing on water at sunset

33:08 - The history and heroes of Cambridge rowing

From novice to Olympian; Cambridge rowing builds champion athletes...

The history and heroes of Cambridge rowing
Alister Taylor, Cambridge University Boat Club

As we continue our trip along the River Cam, Alister Taylor, from Cambridge University's Boat Club, hopped aboard to tell Harry Lewis about the rich history of rowing in Cambridge...

Harry - And there he is, that's Alister Taylor. He's going to be coming on board to tell us a little bit about the heart and then the tradition of rowing in Cambridge, which of course we have to touch on. He's part of the university's boat club. So, if Peter's gonna pull in for us, we'll welcome him aboard. Alister, how you doing? Have you had Alister on before Peter? Because he's nimbly jumped on; he must be a man that's used to the water.

Alister - Not at all. I think you've looked after a few of our guys and they've gone back and forth and done a few bits and pieces.

Harry - Which club have we just picked you up from?

Alister - So you've just picked me up from Downing College Boat Club, which is one of the top clubs in Cambridge. It has developed athletes from novice to Olympics in several examples -  under 23s Annabel Vernon, who is a multiple world champion, multiple Olympian, Olympic medalist - basically learned her trade there. They refined what she'd got as a school kid in Cornwall. Thea Zabell learned to row there; went to under 23s and medaled there. Truly an impressive place for development and we are very lucky as a university to have those clubs.

Harry - How many clubs and how many boats are there? Do you know?

Alister - There are 31 clubs. I would hesitate to put a number on the boats. I would say probably 500-600 just in the university.

Harry - Crikey, Wow. And of course you've got the clubs outside of the university to consider as well. Another thing that Peter mentioned was we're obviously on quite a narrow river, it definitely feels that way. But he said sometimes when all of these people come out in force, you can get up to a thousand boats on the water. I know that there is a bit of a competition coming up this week. What is it that we've got?

Alister - So we've just come off the university May bumps, we're coming into now town bumps. So we do have, I think, six divisions, men's and women's, so that's, I think, 240 boats. So we're looking at over 2000 people racing in town bumps.

Harry - And you don't often see rowers carrying out the sport alongside one another on the water, but this is gonna be slightly different, isn't it? It's quite an exciting time.

Alister - It's possibly the silliest thing you can do in a rowing boat. In Cambridge, our river is so narrow; you can't row side-by-side for more than half a mile or so. So what they do is they put 20 boats in a row, put about a length of clear water between them, push 'em out the river. And then a thumping big cannon goes off, and you try to hit the boat in front of you and not get hit by the boat behind you.

Harry - I mean, it sounds like a lot of fun, but it also sounds like you've gotta be slightly careful of that expensive bit of kit you've got. Would I say irresponsible perhaps?

Alister - I think when you're racing, you can think you're being careful, but you just want to get the boat in front of you. There are breakages, but thankfully we've advanced well beyond where 130+ years ago, Clare College had one of their coxswains killed. Trinity Hall's boat didn't stop in time because the Clare boat had made a really hard bump. Apparently, the bow went straight through his heart.

Harry - Right? I mean, things must have changed since then?

Alister - Thankfully, yes. It's been quite a safety innovation. I think immediately afterwards they started putting these rubber balls on the bow to make sure you can't actually go through people. If they fall off, it's pretty scary.

Harry - And we are just coming up, I know this college on the right hand side, that's Trinity College. That's quite a big one as well. Isn't it?

Alister - Trinity College is the biggest college in Cambridge. Again, it's another one that's been incredibly successful in developing athletes. The stroke of the women's blue boat this year Imogen Grant rowed there. She grew up in Cambridge, but had never rowed. She was a novice there, did the Cambridge university dev squad in her second year, made two university crews, rowed under 23s world championships. Now she's an Olympian, she's a world champion and she's also a med student as well. She's just an incredible all rounder.

Harry - One of those people that really puts me to shame at a pub quiz, I'd say Alistair.

Alister - In fairness, she puts all of us to shame.

Harry - And it's fantastic being in the heart of Cambridge, talking about something that is at the root of Cambridge traditions, but it'll be rude not to mention the boat race as well. For anyone who's listening who doesn't know, it's a massive event in the UK where the Cambridge rowing team takes on the Oxford rowing team. How did that all get started Alistair?

Alister - Well, there were two school boys from Harrow. Both of them were pretty certain their university was the best. So the challenge went down at the end of 1828 and the first boat race was in Henley in 1829. Ever since then, other than 2021 when it was at Ely, it's been on the river course at Putney. It is our reason to be, it is a fantastic event, And it has people who've learnt throughout Cambridge or Oxford as novices to people who've come from the Olympics as gold medalists.

Harry - And I would like to mention women's rowing in particular. It seems like you really nurture and have a lot of successful young female athletes. Where has that come from? Did that part of the club start and originate with the men's team as well?

Alister - That took a long, long time to happen. The first women's boat race was 1927 and that was a very daring thing back then. But even then they weren't allowed to race side by side. It was a processional for a time troll and style. Thankfully we've come a long, long way since then. Now we're all with the same sponsorship, and particularly in Cambridge, we now have one club which brought together the three legacy clubs - the men's club, women's club and the lightweights - all into one Cambridge club. And that's been one of our big developments and something we're very proud of.

Harry - And a real emphasis, it seems throughout this chat, has been just on novices coming through and really succeeding.

Alister - We're really fortunate. There's a stat going around, whether it's made up or not, that about 50% of Cambridge students will row at some point. There's 30,000 students at Cambridge. There are going to be a lot of good athletes. And when you combine that with great coaching and elite student athletes coming in, it's fantastic. We had one of our men's athletes break a 5k world record on the rowing machine - if you've ever been on one, it's frankly ridiculous what he did. The benchmark for elite/international for 2000 meters is six minutes. Tom went faster than that pace for 5k.

Harry - And where are we now?

Alister - So we've just passed the last boathouse on the Cam before Jesus Lock; Christ college, which is, again, one of the oldest boat clubs in Cambridge. And we're now coming past a lot of the resident barges on the river coming towards Jesus Lock and the Jesus Green Lido, which as an Australian, has really surprised me that you can have an open air pool, brutally cold and a hundred yards long. It's fantastic.

Harry - Alistair. I know you've actually got yourself a lunch on the river sorted, so let's drop you off and thanks so much for coming on and sharing a bit of history about the rowing in the river.

Alister - It's my pleasure. It's a fantastic place. And the history of it is what makes it so important and so wonderful.

River sewage

42:06 - Hunting for harmful bacteria in UK rivers

Universities and citizen scientists alike are on the lookout for indicators of faecal matter...

Hunting for harmful bacteria in UK rivers
Susannah Salter, Cambridge University, Anne Miller, Cam Valley Forum

Harry Lewis and James Tytko have been thinking about their early morning swim. Guests along their summer trip down the River Cam have left them worried about the cleanliness of the water and whether it was safe to swim in. Susannah Salter is a research assistant in the Cambridge Department of Veterinary Medicine, she's been looking for the presence of E.coli in the local river. Whilst Susannah is testing the same site daily, Anne Miller from Cam Valley Forum and her army of volunteer heroes have been looking for traces of E.coli and enterococci bacteria across a range of different sites...

James - And here we are with two people who've been monitoring the health of the ecosystem very closely. Can I ask you both to introduce yourselves please?

Anne - I'm Anne Miller from Cam Valley Forum, and we've been taking water samples and getting them analysed to look at the water quality.

Susannah - And I'm Susannah Salter. I'm a research assistant at the Department of Veterinary Medicine, and I've also been monitoring E. Coli in the river.

James - So Harry and I had a dip in the river earlier, did some wild swimming with a local swimming club. And it strikes me now that it probably would've been a good idea to speak to you guys before we jumped in. Should we be worried?

Anne - Well, the key thing is, where were you swimming? If you were swimming a couple of miles downstream of Haslingfield sewage works, I really wouldn't have recommended it. But if you were in the popular swimming spots in Cambridge, like Newnham riverbank club and Sheep's Green, I think it's probably okay, but just so long as you didn't drink it.

Susannah - So I've been measuring a site that's a couple of miles upstream of Cambridge at Byron's pool, which is in a nature reserve between Grantchester and Trumpington, and I've been doing frequent sampling, weekly sampling of the river and measuring E. coli levels. So E. coli is a faecal indicator organism and, week by week, it changes quite a lot actually. And the season depends on what the levels are like in the river.

James - Why are you looking for indicators of faecal matter?

Anne - It's an indication of whether there's poo in the water. And from our point of view as a community group, we are looking for quite a simple way of seeing is this water safe. Personally, I don't want to swim in poo and the bathing water directive sets thresholds at which the levels should be. And so we're trying to see whether the water would be classified as good.

James - And you're a community driven organisation. How do you cooperate with perhaps a more scientific outlet?

Anne - We've got lots of volunteers, but we haven't got very much money. We've done about six batches of samples over the last year at typically 20 sites going as far upstream as about 10 to 15 miles upstream of Cambridge and a few miles downstream of Cambridge. And then we send our samples, water samples that we collect, off to a professionally accredited lab to be analysed. So that's the real sort of science bit. And then we put them on the website so anybody can see what they are, but then Susannah does the more detailed work on a particular site.

Susannah - I started looking at the river because, a few years ago, I was involved in a detailed survey called punt seq, the punt seq project, where we were sampling from different places along the Cam, and then sequencing the DNA in the samples to have a look at what bacteria were present in the river. Lots of interesting results came out of that, but one that piqued my interest was that there was a gut associated pattern in some places, not all the time, though. And one of the places that we saw that was at Byron's pool. And so I wondered whether it was something that was a really rare event or whether it was actually something that happened regularly. And so we thought if we did this pilot study to look in much more detail with much more frequent sampling, that we'd be able to see whether that was something that happened often.

James - And can I ask the both of you to just summarise your sampling techniques?

Anne - We take a clean sample bottle that we get from the labs and we attach it with elastic bands to the end of a rake that go about three metres long, and we dip it into a particular depth in the water, take our samples, and then they all have to get to the lab by, I think, one o'clock in order to be analysed. So it takes us probably a few weeks sometimes before we've got the results back.

Susannah - My sampling technique, on the other hand, the collection of the samples is very similar, but instead of looking at a wide range of places, I'm looking at one place but at a really high frequency. I do the testing myself in my laboratory, in the department of veterinary medicine. And some of the assays that I do are very similar to what's done in the commercial labs, but I'm also comparing that with other kinds of methods. I collect my samples on my way to work in the morning. So they go straight from the river into the lab.

James - Can you talk us through the results of that sampling?

Anne - So the main focus of our work was to try to find out where the sources were, or at least where the major sources were of the pollution that we know is coming into the Cam. And what our work seems to be showing is that the Cambridge sewage works isn't too bad - usually. Sometimes, just once, it was absolutely dreadful, but the main offender seems to be Haslingfield sewage works, which is a few miles upstream of Cambridge and possibly Melbourn sewage works. So we've only done two readings there, which is a little bit further still. And sometimes we've seen leaks coming from the pipes going to the sewage works and so that's completely raw sewage that's flowing into the river. That hopefully doesn't happen for very long because they go and fix it. But we've literally seen raw sewage running down the bank into the river, which is really shocking and shouldn't be happening.

James - Is this sewage in the water that you're describing enough to be harmful to the environment, to people?

Anne - Sometimes. So the readings we got in June at Haslingfield were 17 times higher than the level that the environment agency would call poor quality. So that must be harmful. But on the other hand, a day later, we think it was probably okay. So one of the things that we are really seeing is the way it varies. Everybody goes and has a poo in the morning and a few hours later, it gets through the sewage works and the levels are then higher. By the afternoon, it's not so bad. So what we really, really want and probably Susannah does too, is an instrument that would allow us to measure in real time continuously what's going on.

James - Do you agree? Do your results concur, Susannah?

Susannah - Yeah. So the results that I've had have shown that in winter, the levels are quite high. My sampling site is a couple of kilometres downstream from Haslingfield, and some of the highest levels that I've recorded have coincided with known recorded sewage spills during very bad weather. So this is a storm overflow. This is something that happens when you have really heavy rain and very bad weather, and to stop the system from being overloaded, they release partially treated effluent. The highest levels that I've seen were last year, sort of towards the end of October, which were in excess of 10,000 CFU (colony forming unit) per hundred ml, which is quite a lot. So we were talking about acceptable levels that you would have in bathing waters. Normally that would be significantly below 1000 CFU. So this is very high. And 10,000 is like, if you were to take a gram of fresh faeces and mix it in about 10 litres of water, you'd get a similar result from that. So it is quite a high level to be having a significant distance downstream of the sewage plant, but there are other times where the levels have been quite persistently, unacceptably high, but it doesn't map with one of these storm events or extremely heavy rain. And the water company are not reporting that they have had a spill on those dates. So I don't think that the only explanation of that - of course animals can also be a source of waste material getting into the rivers - but also it's possible that where you have silty stretches along the river, that when you have very heavy rain, for example, it may not be enough to cause a problem at the sewage plant, but it does kick up all of the silt that's at the bottom of the river. The river becomes very turbid. And if you have some of this material sort of surviving in the silt at the bottom of the river, that's normally settled down when it all gets re-suspended in the water, you may see your levels temporarily rise up. And, certainly in terms of how long the levels stay high, that very high level back in October, it stayed above 10,000 CFU for two weeks. So it's not quite as simple as just waste going into the water and then being washed through and then it not being a problem anymore.

James - Those results kind of alarm me when I think about how frivolously we dived into the river earlier. I mean, maybe I'd have kept my mouth more tightly pursed than I did.

Susannha - I collected a sample two days ago and I got my most recent results this morning. And actually this week, the levels are fairly low. So they're around about sort of 5 to 600 CFU. So that's not quite so bad. And I swim in the river too, although not in the winter.

Anne - And we took a reading a couple of weeks ago from pretty much where you were swimming. And I seemed to remember that the reading was about 400, which is okay, but I would keep my mouth shut. And I too swim in the river, but I keep my mouth shut.

James - And moving forward with the data you've collected, what can we do with it? What are the next steps?

Anne - We're using it to apply pressure to the people who are causing the pollution to clean it up. First, we want to find out where it is in a proper scientific way, as well as we can. And so clearly some of it is the responsibility of Anglian Water, who own Haslingfield sewage works, and they actually seem to really be listening to us and we hope are being responsive. We are starting to explore whether we can get hold of an instrument to let us monitor continuously, because we also strongly suspect that it's not just the sewage works that's the problem. It's the farmers emptying out their slurry and things like that. Earlier this year, we were doing some tests outside Cambridge sewage works, and one of our heroes was taking samples of the effluent coming out of the sewage works and there were brown bits in it. And yes, it was what we feared, it was poo. And we discovered that this was because somebody had fly tipped some slurry liquid poo, basically, at the inlet of the sewage works and it had flown through completely overwhelming the system. And that's why there was bits of poo at that instant going into the river

James - For someone who doesn't know a lot about these things. What you've said to me so far today sounds quite alarming. Susannah, is it something we should be more worried about?

Susannah - When I started sampling, I was surprised at how high the levels were too. And clearly this is something that we are looking at locally, but it is a really significant issue all around the country in rivers everywhere. This is a nationwide issue. And because people enjoy our rivers and also our coastlines as well for swimming and for recreation, it's really important that people know that the water's going to be clean. And in some places there is monitoring in place so that people know when there's been an event, that means they can't swim there, but in other places, that's not the case. And for a lot of inland rivers, that's not the case. So yeah, it is something that people really should be concerned about.

Anne - And on top of that, the water companies need to have the power to tell developers that they can't build houses because they haven't got the sewage capacity because that's part of the problem. And the other part of the problem is that, particularly in a dry place like Cambridge, we haven't really got much water in the aquifer. And so what they're doing is, they pump water, clean water out of the chalk aquifer, to put into the river, to flow down the river, to delete the sewage to acceptable levels. That is completely and utterly nuts. So we need to stop the problem at source, have good quality sewage works, and not put excess development where it can't sustainably be.

James - And that's what Cam Valley Forum are all about. That's what they're doing?

Anne - That's right. And if, and if people want to be involved with what we're doing or check out our results, go and have a look on our website, which is camvalleyforum.uk.


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