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Middle/Lower Colne Watermills - Water Head Conservation


mark99

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I only just picked up this titbit. Going "down".

 

If a boat came through Cowroast Lock on the GUC, then on South, entered Cowley Lock <GUC> the water was allowed to go through Cowley Lock into the "long pound" of the GU/Regents. (Water was GUC from Tring summit ressy's).

 

If the boat passed down through Cowley Lock but not Cowroast <ie it entered further down than Cowroast>, the water had to get put into the Colne via this sluice (my image) which is in the sidewall of the Cowley Lock and falls into the Colne. Thus keeping the net flow to the lower Colne = net flow = upper Colne. (Water was Colnes).

 

As mills went out of business, this arrangement was stopped/not required.

 

 

 

 

20140705_145902_resized.jpg

Edited by mark99
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Surely it would be too complicated to control every boat using the canal. How would the lock keeper at Cowley know where the boats had come from in order to make the decision. Did he inspect each boat on arrival and decide what to do?

 

The waterway beside Cowley lock is the Frays River which goes under the cut immediately above the lock. Its not the Colne. 

 

I always assumed that side sluice in the lock was a flood sluice but it would make more sense to put it above the lock. 

 

Or a feed to the long pound from the Frays River with lock empty and gates open. 

 

Definitely intriguing. 

 

I've heard people complaining that lock useage in London on Regents section causes level problems for the long pound so maybe that sluice was used to give an extra supply as well as the water which is provided by the Colne via the bywash at Uxbridge lock. But then most of that disappears just above Uxbridge boat centre. The fact the side sluice is no longer used could explain why the long pound goes low in modern times. Because there is inadequate supply. A direct connection to the Frays River would be undesirable because it could cause flooding problems in London. Having a controlled optional supply might be useful specially as there was probably more traffic density and all the locks are going down. And they were double locks so you would need a lot of water. I can't think where else the water to get through London is coming from. There must be another supply. 

 

I believe they had back pumps as well.

 

 

 

Edited by magnetman
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But why cowroast? The Colne doesn't join until below Lot Mead AFAIK. Surely for river Colne management you would be logging traffic from Common moor down or actually just do Lot Mead. I don't think the cut used any Colne water above there. 

 

Maybe it did.

 

Then there's the Bulbourne and Gade feeders so not all the water coming down is from the reservoirs. 

 

I don't see a mill v canal problem on the Colne above Lot Mead unless I missed a bit further up. 

 

Edited by magnetman
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The main supplies south were the Tring ressies, Wendover Arm in theory! Aldenham ressy, Ruislip ressy, Brent ressy, Rivers Colne, Gade, Bulbourne, Brent.

It was Cowroast as this is 1st lock down south from Tring Summit where there were 5 ressies and Wendover springs and pumps.

 

Before Cowley the Gade flows in and out and Dickenson Mills had sorted water levels/compo with GJC via courts/litigation and then collaboration.

Edited by mark99
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I picked it out of Faulkners History of the GJC I got off Ebay.

 

It's quite dry but he does reference Acts etc rather than opine.

 

Thanks for Frays ref never knew that.

 

One of my dreams is to live in a real watermill. ;)

Edited by mark99
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On 04/04/2019 at 20:57, mark99 said:

I picked it out of Faulkners History of the GJC I got off Ebay.

 

It's quite dry but he does reference Acts etc rather than opine.

 

Thanks for Frays ref never knew that.

 

One of my dreams is to live in a real watermill. ;)

Hi, I made a video about Cowley Lock while it was empty, and explained what you asked. I knew I'd got the information from somewhere - must have been from this book. 

 

Basically, any boats bringing the companies water with them as they descend, took the water into the Paddington Arm. It was known where the boats came from when the toll ticket was inspected at this spot. Any boats not having come from above probably Berkhampstead but I can't find any information about it would have been using river water which would have normally ended up in the Colne had a boat not used it, so at this point it was returned to the river. Why it was important to keep the water in the river at this point can only have been a mill or mills downstream of this point objecting to loss of water.

 

Of by the water - was the photo taken at normal water levels - It looks a little low from the tide mark, but I can see from your photo the bottom of the paddle surround is just spot on the right level.

 

The video:



Cheers,


Mike

Edited by mykaskin
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Thanks Mike. Tallies up. They reportedly  doubled up in the 1800's with lockeepers at Cowrest and Cowley to check, issue tickets. One lockie for a GJC and one for the Mill owners.

 

 

http://www.hertfordshire-genealogy.co.uk/data/answers/answers-2004/ans-0392-mustill.htm

Edited by mark99
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Any suggestions as to where the water came from for all the downhill locks through London?

 

That must have been some massive water demand with pairs of wide locks all the way down. 

 

 

Plus of course locks down toward Brentford. 

 

I reckon that big hole in the side of Cowley lock is related to the water demand for the canal not the mills. 

 

Edited by magnetman
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22 minutes ago, magnetman said:

Any suggestions as to where the water came from for all the downhill locks through London?

(snipped)

I reckon that big hole in the side of Cowley lock is related to the water demand for the canal not the mills.

No MM. It's explained in the previous posts.

The water comes from the reservoirs at Marsworth; Wilstone, Startopsend, and previously Tringford. The supply is augmented from the Colne and other small rivers such as the Gade. Water from these enters at Berkhamsted (River Bulbourne) and Hemel Hempstead (River Gade).

The River is at a lower level beside Cowley lock, so could not have been any kind of 'supply' for the long level.

Edited by Derek R.
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The Brentford Section past the Hanwell Flight would have of course had the Brent as a source. In fact its canalised river. Oh the aroma!

1 hour ago, Derek R. said:

No MM. It's explained in the previous posts.

The water comes from the reservoirs at Marsworth; Wilstone, Startopsend, and previously Tringford. The supply is augmented from the Colne and other small rivers such as the Gade. Water from these enters at Berkhamsted (River Bulbourne) and Hemel Hempstead (River Gade).

The River is at a lower level beside Cowley lock, so could not have been any kind of 'supply' for the long level.

Wilstone Ressy was extended at least twice.

 

Nb Ruislip Ressy is kept so low these days it's not a feeder. The canal feeder outlet is much higher than the ressy level.

Edited by mark99
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3 hours ago, Derek R. said:

No MM. It's explained in the previous posts.

The water comes from the reservoirs at Marsworth; Wilstone, Startopsend, and previously Tringford. The supply is augmented from the Colne and other small rivers such as the Gade. Water from these enters at Berkhamsted (River Bulbourne) and Hemel Hempstead (River Gade).

The River is at a lower level beside Cowley lock, so could not have been any kind of 'supply' for the long level.

There's a borehole at Northchurch too.

 

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I thought at Northchurch it was just a back pump. The one at Cow Roast certainly drew from a borehole, and before they covered the inflow you could fill your can from it - sweet clean water. Same source as Toms Hill Farm bottled water from up the hill above Aldbury if I'm not mistaken. There were days when with no traffic, you could see the bottom of the canal clearly above Cow Roast lock.

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33 minutes ago, Derek R. said:

I thought at Northchurch it was just a back pump. The one at Cow Roast certainly drew from a borehole, and before they covered the inflow you could fill your can from it - sweet clean water. Same source as Toms Hill Farm bottled water from up the hill above Aldbury if I'm not mistaken. There were days when with no traffic, you could see the bottom of the canal clearly above Cow Roast lock.

You still can, when weather conditions are right (it tends to be in frosty conditions). It's quite interesting and spectacular, the shoals of large carp have disappeared over the last few years and sometimes the water is clear for about 50 yards beyond the marina entrance. 

Additional sources of water for the canal are the rivers Chess and Misbourne, the first joins the canal at Ricky and the second, just above Uxbridge, both are chalk streams and suffer badly from water extraction.  The river Gade is another source, joining the canal at Hemel.

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4 minutes ago, mark99 said:

Further north at one time you used to lock down to the Ouse, go along the Ouse and lock up again. Wolverton.

Interesting, as a kid I spent summer holidays with 'fishing mad' rellies at Newport Pagnell (just along from Wolverton), the rivers Ouse and Ouzel (Lovat) were in great condition, water so clear, you could see the fish, underwater weed growth and bottom, great days. I visited Mk last week and revisited some of those spots, 60 years on how things have changed, the Ouse has been re-aligned and the Ouzel has a poor flow of turgid brown water. Real shame.

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15 hours ago, magnetman said:

Any suggestions as to where the water came from for all the downhill locks through London?

 

That must have been some massive water demand with pairs of wide locks all the way down. 

For a given tonnage being carried, wide locks use about the same as narrow ones. They do, however, allow greater tonnages to be carried per day, though possibly not double that carried by a narrow canal. In terms of water supply to usage on canals with a good number of locks, the maximum that can be carried without back pumping is around 2 million tons per annum, as happened on the L&LC, where its usage was always close to its maximum available water supply. The BCN carried a greater tonnage, but over much smaller distances, and often without passing through locks.

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