The Environment Agency....

[nottskev]

I agree entirely that clear and clean are two different things.

But I've seen the argument that some species of coarse fish were more abundant before sewage treatment improvement on the Derwent made the river "cleaner" before - and not always made by bs'ers!

For example, a few years after a £20m upgrade of a treatment plant below Nottingham in the 90's a Midlands Regional Fisheries manager said the clean-up was leaving the river poorer in fish in some ways, the gist being that removal of sewage and other suspended solids had made the water clearer and less rich in organic matter, thus making small fish more vulnerable to predators while having less to feed on. The result had been the disappearance of much aquatic life, especially the spectacular shoals of roach for which the Trent was renowned.

It may seem contrary to common sense, but you'll often see the point made that traces of sewage - I don't mean discharge of raw sewage etc under flood/failure conditions - help support the food chain below some species. Anyone know more about this?

 

[tigger]

I agree entirely that clear and clean are two different things.

But I've seen the argument that some species of coarse fish were more abundant before sewage treatment improvement on the Derwent made the river "cleaner" before - and not always made by bs'ers!

For example, a few years after a £20m upgrade of a treatment plant below Nottingham in the 90's a Midlands Regional Fisheries manager said the clean-up was leaving the river poorer in fish in some ways, the gist being that removal of sewage and other suspended solids had made the water clearer and less rich in organic matter, thus making small fish more vulnerable to predators while having less to feed on. The result had been the disappearance of much aquatic life, especially the spectacular shoals of roach for which the Trent was renowned.

It may seem contrary to common sense, but you'll often see the point made that traces of sewage - I don't mean discharge of raw sewage etc under flood/failure conditions - help support the food chain below some species. Anyone know more about this?

Kev, any form of sewage isn't good for fish or their habitat.
Who ever those peple are who say traces of sewage are beneficial to fish and the river inhabitants just don't know their harris from their elbow.
A purely unpolluted river will hold far more lifeforms than a river with a low amount of sewage.
I have no idea why the people who state such utter nonsense do so mg:.
Same goes for the ocean, anywhere where the water is as near to pristein as it should be there will be a huge difference in the bio mass of life.

 

[Keith M]

On our club forum Keith Speer once commented that every drop of our precious river Lea had probably been through at least five people by the time it reached the Thames.

Keith

 

[Jeff Woodhouse]

I agree entirely that clear and clean are two different things.

But I've seen the argument that some species of coarse fish were more abundant before sewage treatment improvement on the Derwent made the river "cleaner" before - and not always made by bs'ers!

For example, a few years after a £20m upgrade of a treatment plant below Nottingham in the 90's a Midlands Regional Fisheries manager said the clean-up was leaving the river poorer in fish in some ways, the gist being that removal of sewage and other suspended solids had made the water clearer and less rich in organic matter, thus making small fish more vulnerable to predators while having less to feed on. The result had been the disappearance of much aquatic life, especially the spectacular shoals of roach for which the Trent was renowned.

It may seem contrary to common sense, but you'll often see the point made that traces of sewage - I don't mean discharge of raw sewage etc under flood/failure conditions - help support the food chain below some species. Anyone know more about this?

Maybe. I have contact with managers and directors of Thames Water and also many Fisheries people at the EA. Neither agree, BTW.

After one discharge of effluent in 2013 (for which TW were fined £8m), boat owners in Cookham complained of faeces messing up the hulls of their little boats and gin palaces. I phoned up the leader of the area EA Fisheries team at the time, his comment was "Well, a bit of sh!t won't do much harm." This was never brought up in court!

In fact he thought it could do some good by increasing the nitrogen levels that would encourage more suspended algae and therefore provide food for the following spawning season. It's a fact that at Calverton fish farm, they have poly-tents in which they have ponds and get them as green as possible by adding chicken manure. Once they are full of suspended algae they put in up to 100,000 small fry and I was told that in two weeks the ponds are once again clear!

The water companies have a duty under their licences and also the WFD to produce treated sewage as clean as it can possibly be. Yesterday we were working again on a stream that is 90+% treated sewage and the insect life in there is unbelievable. We even netted in 2017 a stone loach and they cannot tolerate any pollution of any kind. The water is, for most of the year, gin clear and therein lies a problem, if fish spawn, where are the fry going to find that all important algae?

Trying to find that balance is difficult.

Yesterday...



Edit bit: Those three lads at the back are French Scouts. Only one other is an angler, where are our young volunteers? Lying down in bivvies carp fishing, maybe?

 

[nottskev]

Interesting post, Jeff. I'd like to agree with the "cleaner must be better" view. Life would be simpler, and I'd have better fishing if it applied to one of my local rivers!

But the point I'm asking about isn't answered by saying cleaner must be better. The slump on the lower Derwent has gone hand in hand with improved water treatment, and now, and for the past few years, the river, including the lower river down to the confluence, has been producing very little other than grayling - which we rarely saw on those lower sections.

Grayling demand good water quality, so if the river is "clean"enough to make them thrive, why aren't the other species thriving too? What kind of conditions in a river favour grayling but lead to a conspicuous slump in coarse species which previously thrived there? We are talking lower river here, with plenty of depth and variation in habitat, not just the typical territory grayling usually favour.

Sorry to go on, but that's the question the EA had no real answer for, and neither has anyone else I've spoken to.

 

[Jeff Woodhouse]

I honestly don't know, Kevin. Take the Test for example, it has a good head of grayling, and trout, salmon, dace and roach to good figures. Is it peaty in colour? Perhaps it's more acidic as opposed to the Test that could be more alkaline. It could just be that there isn't much in the way of spawning habitat for roach and other cyprinids, something we're trying to achieve on our tiny river (it's only 3kms long before it reaches the Thames.)

PS: I hooked a nice perch as well last time I fished the Test, about 1½lbs, and lost the little blighter at the net!

 

[nottskev]

I honestly don't know, Kevin. Take the Test for example, it has a good head of grayling, and trout, salmon, dace and roach to good figures. Is it peaty in colour? Perhaps it's more acidic as opposed to the Test that could be more alkaline. It could just be that there isn't much in the way of spawning habitat for roach and other cyprinids, something we're trying to achieve on our tiny river (it's only 3kms long before it reaches the Thames.)

PS: I hooked a nice perch as well last time I fished the Test, about 1½lbs, and lost the little blighter at the net!

It's mysterious. It's not long since it had roach, chub, perch, bream, dace, and, latterly, barbel, in abundance, so the coarse fish clearly were spawning and thriving in the past.

Before I moved to live round here, I used to travel the 80m down from the northwest to fish it. On one occasion I caught 26 good chub and had run of bait by lunchtime. These days, I wouldn't bet on catching one. A friend with a big local match-fishing background for one of the top teams around here retired to live by the Derwent for the great fishing; he knows the place well, but can't catch a chub or a barbel locally these last few years.

When I first moved here in 2004, in the right swims, you threw in casters and the water boiled with roach and dace. Now, you can get a few grayling then that's it. It had great perch fishing - lean pickings now.

Graham - The Crow - used to travel over here for the|Derwent barbel fishing, but he'd long stopped doing so as the fish disappeared.

Some local club officials say the river has always gone in cycles. I'm familiar with cycles where, say, roach and dace give way to chub, which give way to barbel which etc etc. But a cycle where coarse fish disappear and the grayling population explodes?

 

[tigger]

Interesting post, Jeff. I'd like to agree with the "cleaner must be better" view. Life would be simpler, and I'd have better fishing if it applied to one of my local rivers!

Cleaner is better, i'm amazed you can't get your head round it Kev.
Sewage is lethal to fish and pretty much all aquatic life it de-oxygenates the water and that kills most things in the river!
Run off from fileds is also lethal. Farmers are only supposed to spread slurry in certain conditions and at certain times of year for this reason, but far too many seem to ignore the laws when it suites them and fekc the consequences.
Sewage causes silt which covers the gravel beds where fish spawn and smothers the spawn and suffocates it! Sewage and run off cause huge amounts of nitrates which cause giant alea blooms that cause unnatural growth of plants which choke the river.... the detrimental effects go on.
I don't think there are any good side effects from sewage whatsoever.

I find it quite shocking that anyone can think sewage is good for the rivers!

 

[nottskev]

Cleaner is better, i'm amazed you can't get your head round it Kev.
Sewage is lethal to fish and pretty much all aquatic life it de-oxygenates the water and that kills most things in the river!
Run off from fileds is also lethal. Farmers are only supposed to spread slurry in certain conditions and at certain times of year for this reason, but far too many seem to ignore the laws when it suites them and fekc the consequences.
Sewage causes silt which covers the gravel beds where fish spawn and smothers the spawn and suffocates it! Sewage and run off cause huge amounts of nitrates which cause giant alea blooms that cause unnatural growth of plants which choke the river.... the detrimental effects go on.
I don't think there are any good side effects from sewage whatsoever.

I find it quite shocking that anyone can think sewage is good for the rivers!

I hear what you're saying...it's not a matter of me getting my head around round it in theory, it's a matter of why cleaner is better doesn't seem to be working in practice.

How would you figure out the situation I'm describing? A cleaner river where coarse stocks collapse but a species of game fish is having a population explosion? Aren't grayling supposed to be a more sensitive barometer of the health of a river, and all that?

 

[tigger]

I hear what you're saying...it's not a matter of me getting my head around round it in theory, it's a matter of why cleaner is better doesn't seem to be working in practice.

How would you figure out the situation I'm describing? A cleaner river where coarse stocks collapse but a species of game fish is having a population explosion? Aren't grayling supposed to be a more sensitive barometer of the health of a river, and all that?

I don't know Kev, but the decline in coarse fish is certainely not because of better water quality.

Did you see Jerremy Wades moster river the other night?...he was on the Ganges and it's seriously polluted! The river was pretty much void of life.
He travelled up river to parts above the sewage works etc and it was like a totally different river and still had the mahseer present.

 

[nottskev]

Yes, I did. It was good. I like the current series. It's a better format than that stuff where he hypes it up......"..could this be the fish that's been abducting children from the local villages?..' and that type of hokum.

 

[Jeff Woodhouse]

Sewage causes silt which covers the gravel beds where fish spawn and smothers the spawn and suffocates it!

That's what is known as 'sewage sludge' and yes, it can be detrimental to a river, but most of it is trapped in the siltation beds in STWs then sold off to farmers and that's where some problems can stem from. Some nitrate content can be good, as I said, it promotes suspended algae that fry can feed on. However, I will agree that you don't want DO levels to fall to 4mgs/L (about 4 parts per million) as that's when fish do start to suffer.

The lower Ganges is dreadfully poor in quality, but that's a nation who's environmental interests are low on the agenda.

 

[Tee-Cee]

I don't know your river Kev, or its history, so can you say what the 'official' verdict around is the decline of the coarse fish from the EA? I'm assuming this is not a sudden happening but one that has gradually got worse and worse over a number of years?
Likewise, I'm assuming the EA carry out regular tests on the water and from this surely they can say, with all the experience they have around such matters, what is going on? I cannot believe someone doesn't know the actual cause, or am I being nieve?

Similarly, if sewage or run off is the prime cause, then tests would surely show this to be the case and consequently who is responsible, as happens when companies are taken to court?

All of the above seems obvious to me, but then I'm sure it is a lot more complicated as something would've been done to arrest the situation by now..................

 

[nottskev]

Morning Tee-cee. Regarding water quality, the peculiar thing seems to be that the coarse fish decline coincides with the cleaning up of the river through water treatment improvements.

The decline to the point where we only catch a few small grayling seems to have taken 15-20 years.

I brought it up as the thread was about the EA, and someone asked whether a river could ever be "too clean". It's not that I believe a a polluted river is preferable to a clean one. But it does raise questions when ostensible water quality improvement coincides with replacement of a huge coarse fish population with a relatively small number of game fish. Something quite similar seems to have happened to another Trent tributary, the Dove, which used to have great stocks of roach, dace, chub and latterly barbel. We stopped going after several visits over a couple of years produced only trout and grayling. I'm happy to admit I'm less familiar with the Dove, though.

As to the EA, here's the main bit of a reply to an official from one of the three clubs controlling the lower 15 miles. The EA acknowledges that the same issues are being raised by all three.


"With regards to changes / shifts in fish populations in the lower Derwent. I have discussed similar issues with fishing performance on the lower Derwent with representatives from Derby County Angling Club and Earl of Harrington. At present it would be speculation to try and say if and what the issues are as we don’t have any concrete evidence, only anecdotal reports from anglers. Some general comments would be that: (i) water quality on the whole has improved a lot over the last few decades. Grayling are very intolerant of pollution, in particular to ammonia. Increasing numbers of grayling is a good sign. (ii) Lower numbers of Chub and Barbel could be due to a number of issues; habitat suitability may have shifted now that water quality has improved and the river now may favour other species (Grayling, Trout). (iii) Current stocking levels may not be at the same levels of decades ago when the numbers of chub and barbel in the river may have been artificially enhanced. (iv) Predation by avian predators may have increased; but this would also affect grayling populations…"

Let us know if you find the cause(s) in there! The reply fixes on chub and barbel, so no mention of the disappeared stocks of other coarse species, and the only open inquiry seems to focus, questionably, on the barbel population rather than any others.

"....... we are running a Barbel project on the Trent and Lower Derwent to try and understand the health of the population. We already have several hundred scale samples to analyse; from this we can look at growth rates, compare these to other rivers and try to understand if there are any bottlenecks in the population. I will let you know as soon as we have further information on this project; if these results do not give us enough information we may need to undertake further survey work to try and understand the reason for a decline in fishery performance."

 

[rich66]

I sometimes think that we confuse clean with clear ? Just because the water looks clean/clear is it ?

We have to ask ourselves what damage are the insecticides and pesticides that get into our water doing, plus we have the effect of ethinyl-estradiol (EE2) which is found in most common birth control pills and other hormones/hormone blockers. Which has a documented affect on the sex of fish, perhaps we are just slowly turning them all female. This would account for a slow decline, plus all the other factors mentions predation, lack of spawning sites, food etc etc

Around 2010 the EU I believe tried to tighten the laws on the removal of EE2 from our waste water that is pumped back into rivers, but I don’t think it ever got any where with the massive outcry from water companies etc.

Then there the signal crayfish for instance, which just devours everything in its path, from invertebrates that fish feed on to the fish eggs and fry.

There’s probably far far more factors than we realise

Estrogen in birth control pills has a negative impact on fish -- ScienceDaily

Something fishy in the water? - NHS


YouTube

 

[The bad one]

Rich the problems are far greater than just EE2s We are now up to around 300 known endocine substances that are making fish infertile. All coming through the lovely Water Treatment works. In all that clean water the Utilities companies tell us are so clean.... poppy cock!

 

[rich66]

Rich the problems are far greater than just EE2s We are now up to around 300 known endocine substances that are making fish infertile. All coming through the lovely Water Treatment works. In all that clean water the Utilities companies tell us are so clean.... poppy cock!

I know it’s ridiculous really when you sit back and think about what we are pouring into the waters and eventually back into the food chain etc.

 

[Philip]

Allot of this just comes down to the definition of "clean".

Is water thats drinkable to humans "clean" ? ...I suspect the general public would say yes. Is that same water also beneficial for a healthy river and food chain ? ...thats when it starts to get more complex to anwser !

I am sure there are all sorts of things in treated water that are probably not so good for fish or the enviroment but I do also wonder if allot of the water being pumped in is killing the food chain at its base at there is no food as such held within it.

Even a goldfish in a bowl of tapwater would die of starvation eventually.

 

[no-one in particular]

I am wondering if it's right that water can be too clean for coarse species, they don't live in upper parts of rivers generally where the water is cleaner.

 

[Tee-Cee]

Kev.........If and when the EA tested your water and came up with 'the water is clean' (if that is what they say!) do they issue figures which actually show what the samples taken show in (say) parts per million? Surely, if pesticides etc. etc. are shown to be higher than they should, this would show up in the tests, or is that simplifying the issue too much?

It's all very well saying this or that is the cause, but any conclusions must, surely, be based on scientific fact, and not on what folk think might be the cause? Some above mention EE2 as a possible cause. Does the EA agree or dispute this suggestion and if it is the former are they saying they cannot do anything about is - just a fact of how we live etc.?

Is it too simplistic to take water samples over a given length of water (along high, middle and lower stretches, for example) test them with every test known to the EA and then ask the top bods in (say) universities to give an opinion, independently? I cannot think we don't have the means to at least arrive at the likely cause, regardless of whether we can make the necessary changes to rectify the situation?

Questions, questions, but who has the answers, eh??


ps I recall a film called 'Erin Brokovich'...............................she took years to find who was responsible for killing folk via polution, but got there in the end...............Not quite the same thing, but it showed that someone, somewhere has to be responsible and pay the price..