Pollution from Shropshire lead mines still reaches the Severn

This information from an Environment Agency page will come as no surprise to regular readers:

There is evidence of lead mining in the Minsterley area of the Shropshire Hills since pre-Roman times. The importance of lead mining grew during the medieval period and had become a major part of the economy of Snailbeach and Minsterley by the late 16th and 18th centuries, respectively. 

This continued to grow throughout the 17th and 18th centuries, until the 19th century, when the mining activity was at its peak. During the 1870s the Stiperstones area was one of Britain’s main sources of lead.

But the page goes on to say that these long-abandoned mines still present a significant pollution problem:

Minsterley Brook is polluted in its headwaters by cadmium, however after the input of a mine water discharge known as Wood Adit at Gravels, the watercourse is polluted along its length for cadmium, lead and zinc down to the confluence with Rea Brook. 

Hogstow Brook is polluted along its length by cadmium, lead and zinc from its source at the outflow of the Boat Level mine drainage tunnel. Further metal polluted inputs enter the watercourse from Snailbeach. 

After the confluence of Rea Brook and Minsterley Brook, Rea Brook is still polluted at the sampling point at Hook-a-Gate Bridge near Bayston Hill. However, Rea Brook is not polluted, when assessed as an annual average, approximately 8km downstream of Hook-a-Gate Bridge at Coleham in the centre of Shrewsbury. 

Rea Brook flows for 25 miles from Marton Pool near the Welsh border to the Severn at Shrewsbury, passing Minsterley, Pontesbury, Hanwood, Hook-a-Gate and Bayston Hill on the way. 

It is joined at Minsterley by the Minsterley Brook, which rises on Stapeley Hill and runs through the wooded Hope Valley. The Hogstow Brook is a smaller stream that joins the Minsterley Brook shortly before its confluence with the Rea Brook.

There is another page on the pollution of these rivers on Restoring Europe's Rivers, but it's 10 years old and I don't know its provenance.

But, for what its worth, it says:

The mines were worked for mainly lead ores, but also zinc ore and latterly barites until closure in the 1940s, leaving spoil deposits and drainage adits which discharge to Minsterley Brook at various points. The mines are a significant source of heavy metal pollution in the catchment, and the discharges from them represent one of the longest continuous sources of pollution in the whole Severn River Basin.

Environment Agency routine monitoring found there were high levels of zinc in Minsterley Brook over most of its length, exceeding the Environmental Quality Standards (EQS) for the brook (75ug/l). As a result, the watercourse isn't achieving the 'Good status' for water quality as set out in our Severn River Basin Plan. 

The Boat Level adit discharge is the main source of the zinc (around 3000kg per annum) and other heavy metals, such as cadmium and lead, and discharges these pollutants into the Hogstow Brook. Immediately downstream of the Boat Level adit the zinc concentrations are up to 47x the EQS. 

At Minsterley, the zinc concentrations are 8x the EQS. Downstream of the mines, concentrations exceed the EQS for over 15km, until the Rea Brook reaches Hanwood and dilution from other rivers lowers the concentration to below the EQS.

Ecological surveys of the brooks have found aquatic insects were suffering as a result of these heavy metals, which can settle in river sediments. There is also a lower than expected population of small fish species.

To end on a happier note, the pretty little bridge in the photograph above crosses the Minsterley Brook in the churchyard of Holy Trinity, Hope.