Why Is The River Esk Red?

If you look at the river Esk in Ironmills Park you will observe a red colouration in the water. In fact it is the river bed that is red and most locals are aware that this is due to high levels of Iron in the river. One might think this is why the park is named Ironmills but I think the name Ironmills came from the Iron mill that used to operate in the park at one time.

So where does the Iron in the river Esk come from? Is it a good thing or might it be detrimental; and if it is detrimental what can be done about it?

Iron is present in coal seams and mud stones in the form of pyrite (ferrous sulphide). Midlothian had many mines that have now closed down leaving the coal seams stagnant. As the water table lowers in these disused mines, the air oxidizes the pyrite and along with bacteria in the seams, the acidity levels drop to pH 2 or 3. Acidic water can then discharge from these old mines with the iron in its oxidized state.  The oxidized iron can then precipitate on the river bed when the pH of the river water rises above 6. In these alkaline conditions the iron is converted to ferric hydroxide. The iron precipitate discolours the rivers leaving unsightly ochrous deposits and the oxidation process leads to the depletion of the oxygen in the river water.

So it comes from disused mines, certain conditions cause it to deposit and it’s a bad thing. I am aware that some disused mines have to have water levels managed by human intervention and there are controlled releases of water from these mines. So I guess there are times when the Iron deposits are particularly bad and other times when they might be insignificant. But I’m not sure.

The internet is a wonderful thing – I found these 2 articles and have extracted the most relevant info;

Ferruginous waters discharging from disused mines have been a problem for decades, but with the closure of so many coalmines, beginning in the 1950s and continuing into the 1990s, the problem has been accentuated. As mines closed, pumping stopped or was reduced and groundwater levels recovered. The rate of recovery depends very much on the rate of flow into the workings and their extent. In some cases complete recovery may take several decades. As well as contaminating rivers, rising acidic ferruginous groundwater may in the future contaminate aquifers overlying the Coal Measures such as the Permian Basal Sands, the Magnesian Limestone and the Permo-Triassic sandstones. The rise of water levels can also lead to subsidence as a result of the weakening and eventual collapse of strata left to support the roof in shallow workings. The corrosion of engineering structures that contain Portland Cement and the flooding of landfills are other problems. The quality of the discharge from disused mines improves gradually with time as the rising groundwater flushes the acidic oxidation products out of the Coal Measures, but the process can take many years. Increasingly widespread pollution by such acidic ferruginous waters seems to be inevitable unless expensive treatment methods are introduced or pumping from some mines is continued to control the discharges. The circulation of contaminated ferruginous waters through artificially constructed wetlands, which improves their quality, is being investigated as a relatively cheap solution to the problem. Responsibility for pollution by acid mine-waters is very unclear. Mine owners who permit pollution from abandoned mines are given indemnity under the Water Resources Act of 1991 and, in Scotland, the Control of Pollution Act of 1974. The Environment Act 1995 removed this defence but only for mines abandoned after 1999. This leaves the legal responsibility and the problem unresolved.

Abandoned mines are one of the most significant pollution threats in Britain. Our legacy of mining for coal, metal ores and other minerals dates back to the Bronze Age. Many thousands of mines have been abandoned and now discharge minewater containing heavy metals and other pollutants into our watercourses. Other more recently closed mines are still filling up with groundwater and will start discharging in the future.

Nine percent of rivers in England and Wales, and two percent in Scotland are at risk of failing to meet their Water Framework Directive targets of good chemical and ecological status because of abandoned mines. These rivers carry some of the biggest discharges of metals such as cadmium, iron, copper and zinc to the seas around Britain.

The legal position in the UK is such that no-one can be held liable for the pollution from the majority of mines. It is only since 1999 that the operator of a mine has had any obligation to deal with the consequences of abandonment. The Environment Agency, Scottish Environment Protection Agency (SEPA) and Coal Authority are leading efforts to deal with the problem.

Thirteenth century coal workings near Dalkeith in Scotland still discharge acidic, iron rich waters into the River Esk (Younger and Adams, 1999).

Looking through my old files I came across a newspaper article from Feb 1996 in the Edinburgh Evening News.

“Lothian Streams Run Red As Pollution Battle Rages” – “Who’ll Clean Up Our Rivers?”

So what do you think? Should there be more effort to clean up the Esk?

I also came across an angling association with an interest in the Esk.

http://www.fishingaround-scotland.com/riveresk.htm

The river Esk runs from the North Esk reservoir down the Pentland hills in to Penicuik then onto Dalkieth then flows to Musselburgh where it meets the Firth of Forth. The river was once full of trout and slamon the latter many years ago. Through the years the esk served the papermaking mills of Penicuik and surrounding area. The mills have long gone and it seems so have many of the fish. The river was fished for trout by man and boy for many years, it was then stocked with brown trout by the Eskvally Angling Association.
Many areas of the river have under gone redevelopment seeing housing built on the banks of the river where the mills used to employ many people as the area developed sadly the river banks did not, now many parts of the river are hidden by over grown trees and under growth. Even the foot bridge that lead you into the braes at Penicuik has long gone. Foot paths have been made along parts of the river but most of them follow the old Penicuik Railway line which used to link Penicuik to Roslin Rosewell Bonnyrigg and Dalkeith.
The river has been subject to pollution in the past years and a land slip a few years ago was the last time pollution entered this once fine river. Now that the pollution which we believe was lime that polluted the river has been washed out, by the several winter spates the river is once again starting to look clean and fresh. What it needs now is for some volunteers to make access to the areas to allow fishing to recommence on the river. Who knows possibly in years to come salmon ladders may be erected on the few weirs that prevent them from returning to the once happy spawning grounds. How ever getting access to the river and stocking it with trout would be a start and possibly bring anglers back to the banks of the river Esk. This would require the co opperation of land owners and the District Council.
Penicuik once known as the paper making town is no longer a paper making town  and river is left to do what it does, with a little help it could bring visitors to the area not only to fish, but use the walkways and local services breathing some new life into the town.An approach has been made to the local Penicuik District Coucil who are in favour of supporting this idea.With the assistance of the local tackle shop Fishers and some members of the local community this could be achieved along with the land owners permission to cut back some trees and under growth to make access to the river, enabling access to fish. A permit system could be introduced to facilitate the costs of stocking the river with fish, and over seen by some volunteers.  Some volunteers have already been identified and willing to give up some time to help achieve the goals set out. 
The intention would be to make access to the river from the Telfor bridge to Roslin glen at the top of the weir how ever Auchendinny would be a more realistic target to begin with. So willing to get involved or lend a hand contact tom@fishingaround-scotland.com to register an interest and  you will be kept up to date with where we are and what is happening.

I have joined the blog for the Eskvalley Angling Association and who knows where that might lead. Being a girl, fishing doesn’t feature in my activities but......my dad did take me fishing in Peebles when I was little and I did fish off the West Coast of Scotland. I remember catching a lot of Mackerel. Oh and I did go on one of these Jeep off road days which included a shot at fishing in a well stocked “pond”. That was easy and the instructor told me that girls often do well at fishing because of the pheromones! So ladies – if you are releasing pheromones and want to catch fish – go for it!