Canal colour

[Philip]

Over the last couple of weeks I've travelled the whole Grand Union mainline, the short bit of the Oxford and the Shropshire Union B&LJ amongst others and noticed the different colour of the water in different canals.

 

The Grand Union is almost a dark green in places but what I'm most intrigued by is why the Shropshire Union is like a chocolatey brown in most places (implying lots of mud being churned up through frequent use) and yet the busier stretch of canal between Blisworth, Braunston and Napton isn't like this, it is just a pale murky colour. I would've thought the busier the stretch of canal, the darker brown the water is? Is it more to do with the type of fertiliser used in the area or something?

[Captain Pegg]

There has been a lot of heavy rain in some places recently which will have resulted in a lot of run off from fields. I suspect this may be the principal cause of the differences you observed. There will be some natural variation in any case but after periods of heavy rain the colour of water in the canal does change.

 

JP

Edited August 23, 2020 by Captain Pegg

[tree monkey]

57 minutes ago, Philip said:

Over the last couple of weeks I've travelled the whole Grand Union mainline, the short bit of the Oxford and the Shropshire Union B&LJ amongst others and noticed the different colour of the water in different canals.

 

The Grand Union is almost a dark green in places but what I'm most intrigued by is why the Shropshire Union is like a chocolatey brown in most places (implying lots of mud being churned up through frequent use) and yet the busier stretch of canal between Blisworth, Braunston and Napton isn't like this, it is just a pale murky colour. I would've thought the busier the stretch of canal, the darker brown the water is? Is it more to do with the type of fertiliser used in the area or something?

The soil that is washed into the canal will be different in different areas, clay, chalk, peat etc. All of these will have a different hue, peat will be blackish, clay brownish, chalk milky.

Different ratios of the above will have different hues, the green could point to algae and points to a fertile/over fertile run off.

The T&M has an orange colour because of the iron rich water feed from Worsley  and there is an area on the GU where it can be crystal clear because the water is pumped from an underground aquifer.

 

Al least that's my ideas

[matty40s]

The GU on that pound went very orange in February when it rained solidly for days and the Nene was in flood.

[Captain Pegg]

15 minutes ago, tree monkey said:

The soil that is washed into the canal will be different in different areas, clay, chalk, peat etc. All of these will have a different hue, peat will be blackish, clay brownish, chalk milky.

Different ratios of the above will have different hues, the green could point to algae and points to a fertile/over fertile run off.

The T&M has an orange colour because of the iron rich water feed from Worsley  and there is an area on the GU where it can be crystal clear because the water is pumped from an underground aquifer.

 

Al least that's my ideas

That’s the Bridgwater that’s orange at Worsley. The T&M is orange at Kidsgrove for the same reasons. For obvious reasons water doesn’t find its way from Worsley to Kidsgrove.

 

Why do you think the water is so clear on the Wolverhampton level and not just on the bits that aren’t busy? The water is also quite clear on the Birmingham level below Factory locks. The Erewash is even clearer.

 

JP

Edited August 23, 2020 by Captain Pegg

[matty40s]

We were probably one of the first boats to go down through Leicester when lockdown was ended. The stretch from Kilby Bridge through to the Soar at Kings Lock was mostly clear as a bell and you could see everything underwater. 

[tree monkey]

47 minutes ago, Captain Pegg said:

That’s the Bridgwater that’s orange at Worsley. The T&M is orange at Kidsgrove for the same reasons. For obvious reasons water doesn’t find its way from Worsley to Kidsgrove.

 

Why do you think the water is so clear on the Wolverhampton level and not just on the bits that aren’t busy? The water is also quite clear on the Birmingham level below Factory locks. The Erewash is even clearer.

 

JP

Pah Bridgewater/T&M basically the same place

serves me right for not bothering to think before pressing send.

 

I imagine a lot would depend on water sources,  canal construction and flow but I am guessing now.

how cloudy the water gets and how quickly it clears would depend a bit on sediment size, fine silt will take a long time to settle, whilst sand might not even be disturbed by boat movements, the % mix of sediment sizes would contribute to how slowly the water will clear

[Athy]

1 hour ago, tree monkey said:

 

 

The T&M has an orange colour because of the iron rich water feed from Worsley 

There were streams in the Derbyshire Peak District which ran that colour - known by the locals as "ockerwatter".

[tree monkey]

14 minutes ago, Athy said:

There were streams in the Derbyshire Peak District which ran that colour - known by the locals as "ockerwatter".

I used to work at an old water mill and it was fed by leats from underground mine workings and they were the same

[NB Esk]

1 hour ago, tree monkey said:

I used to work at an old water mill and it was fed by leats from underground mine workings and they were the same

 

This is the reason some streams in mining areas are orange, due to ockerwatter.  Iron ore deposits resulting in water stained by ochre. 

This is a disused mine I explored c1981.

 

 

[tree monkey]

1 hour ago, NB Esk said:

 

This is the reason some streams in mining areas are orange, due to ockerwatter.  Iron ore deposits resulting in water stained by ochre. 

This is a disused mine I explored c1981.

 

 

You would NOT get me in there