Mangerton Mill to Milton Mill, 27 Feb 2015 - by Geoff May:
The purpose of the walk was to conduct a first-hand survey of the various barriers to fish migration on the stretch
of the Mangerton Brook between Mangerton Mill and Milton Mill. Mangerton Brook is a tributary of the River Asker
joining it at Bradpole.
The migration of salmon and sea trout from the sea at West Bay up the Brit/Asker river system should, in
theory, be possible following the installation of fish passes at Palmers Brewery (2011, at the confluence of
the Brit and Asker) and Jessop's Flood Defence Weir on the Asker (2010). Two feasibility studies in relation
to the removal of barriers to fish migration on this part of the river were conducted in 2012 (Apem) and 2013
(Fishway Engineering), as well as a further review by the Environment Agency/Frome, Piddle Fisheries Association/Friends
of Rivers Programme Board (2013).
The latter produced a map of this section of the river which is included below.
The walk commenced at Mangerton Mill:
Those taking part were:
The weather was glorious - sunny, crisp and dry - and everywhere on the walk we were treated to literally carpets of snowdrops:
MANGERTON MILL - WEIR WITH HATCHES
The first task was to establish the nature of the barriers at Mangerton Mill. In essence it appears quite straightforward:
the mill leat is taken off the main river at a weir with hatches some 200 metres or so upstream of the mill
beyond the field which serves as a site for touring caravans during the summer season. It is accessed by a
footpath running alongside the river.
Weir with hatches upstream of Mangerton Mill - Barrier 4 on map:
Over the passage of time the mill leat has become wider so that to the casual observer it appears to be the
main stream from the weir to the Mill. The leat passes over the water wheel at the Mill into a tail pool.
It then continues alongside the river by the side of the track leading from the lane to the Mill for about
100 metres before rejoining the river just before that lane.
Mill leat at Mangerton Mill (right) rejoins the river just before lane:
The first barrier to be tackled, therefore, is the weir with hatches (Barrier 4) above Mangerton Mill.
One issue that will also have to be considered is whether fish migrating upstream will take a right and
follow the mill leat up to the tail pool at the Mill rather than taking the left hand stream to the weir.
We then followed the course of the river through the grounds of Mangerton House and across the field to Milton Mill.
The fishermen among us commented that this stretch of river appeared to provide excellent habitat for
migratory fish with numerous stretches of gravel offering perfect locations for spawning.
Gravel bed upstream of Mangerton House:
MILTON MILL - LARGE WEIR UPSTREAM OF MILTON MILL
The second task which we had set ourselves was to understand the various barriers in the system of streams
and mill leats around Milton Mill. The owner had kindly given permission for us to walk through the grounds
of the MIll to do this.
Again the situation seems quite straightforward: the mill leat is taken off the
river at a large weir about five hundred metres above Milton Mill. It is accessed through the field at
the bottom of Larcombe Lane where it enters Milton Mill; a public footpath runs through this field to a
bridge across the river just below the weir.
Field below West Milton Weir, with public footpath leading to bridge across the river near left:
Weir is located at the top of the field on the right.
West Milton Weir above Millton Mill - Barrier 1 on map:
The mill leat runs from the top right-hand of the weir through a hatch, down along the side of the field
mentioned above, under Larcombe Lane into the grounds of Milton Mill and through a further weir(Barrier 2)
where the flow was historically diverted through the mill (now blocked off). It then flows on through the
grounds, taking two dog-legged turns with one set of sharp drops at the second dog-leg, eventually rejoining
the river some 50 metres further on.
Hatch where mill leat is taken from river above the weir:
Weir on the leat above which flow was originally diverted through Mill (Barrier 2):
Second dog-leg in mill leat showing first sharp drop:
Mill leat (left) rejoins the river below Milton Mill:
The second barrier to be tackled is the weir (Barrier 1) above Milton Mill. This is a substantial
structure and will require a major engineering solution. On the face of it access may be a problem for
contractors. One other issue that may have to be considered is the single step on the river where it
skirts Milton Mill before joining up with the leat (Barrier 3). This is not a significant obstacle and
may not present a barrier to fish migration when the river is in spate.
Single step in river below West Milton Weir (Barrier 3):
As at Mangerton Mill, there is the issue of whether migrating fish may be inclined to swim up the mill leat rather than up
the river at the confluence.
The various barriers on the mill leats at both Mangerton Mill and Milton Mill do not appear relevant to fish migration.
With thanks to the owners of Mangerton Mill and Milton Mill who gave permission for us to access the various
barriers on the river, and to the Marquis of Lorne where we had a splendid lunch.
MAP OF MANGERTON BROOK FROM MANGERTON MILL TO MILTON MILL:
River walk in 2014:
“CELEBRATORY WALK” - Sunday 12 October 2014 - by Geoff May
This walk marked the completion of the fish pass at Gundry's Weir. It began at Palmers Brewery, followed the River Asker up to Jessop's
Weir and then across Coneygar and Victoria Grove, through the fields, past South Mills finishing up at Gundry's Weir on the River Brit.
These three weirs - Palmers Brewery, Jessop's and Gundry's- were the major barriers to fish migration from the sea at West Bay harbour.
Now the fish passes are completed, fish are able to negotiate these barriers and migrate significant distances up the river system in
order to spawn.
Rendezvous for the walk was at the weir at Palmers Brewery. The select few that could make it included Roger Guppy, Pat Hughes, Geoff and Diane May and John Wreford. The weather was distinctly autumnal but we were spared the rain. The purpose of the walk was to visit the three major obstacles to fish migration on the Brit and Asker nearest to the sea.
The Larinier fish pass at Palmers Brewery was completed in August 2011. It was the second fish pass installed on the river at the
confluence of the Brit and Asker. The project was initiated by the Frome, Piddle and West Dorset Fisheries Association who
obtained the funding from Westcountry Rivers Trust. The prefabricated structure was installed on a concrete ramp built into
one of the existing hatches which are adjacent to the weir. Prior to its installation, fish migration was possible through the
hatches but only if they were opened. Now salmon and sea trout have unhindered passage up the river. We were pleased to note that, three
years on, everything works as planned.
We crossed the South Street near Morrison's Supermarket and walked along the path to Asker Meadows. This path has been upgraded
in recent years by Bridport Town Council and now provides a very picturesque walk.
Our first stop was the pool at South Mills, an enchanting area of water hollowed out by the river.
We then walked up to the new bridge linking the new housing development at New Zealand with Asker Meadows. We were able to
inspect the area of land beside the development that will soon become a designated nature reserve - a welcome addition to
Pressing on, we walked on up the Asker, past the gauging station (below, which is not felt to impede fish migration) and
up to the bridge over the river at the easterly end of East Street, near the roundabout.
From there it is a short walk along Sea Road North to Jessop's Weir.
Dating from March 2010, this was the first of the fish passes to be installed. It is a so-called "artisan" solution, and was
constructed thanks to the determined efforts of Roger Genge at the Environment Agency to see what could be done in the
absence of funding for a conventional fish ladder. The ladder comprises approximately 25 sections of battens made from
recycled plastic and secured to the concrete with steel supports. It is an ingenious design and the indications are that
it facilitates a degree of fish migration.
Leaving Jessop's behind we made our way over Coneygar and Victoria Grove to North Mills to find extensive in-river works
in progress. This was clearly aimed to remove much of the silt which has built up in order to reduce the risk of flooding.
Gundry's Weir is part of the flood defence structures on the Brit. It presented an insurmountable obstacle to fish
migration as witnessed by the numerous sightings of large fish attempting to leap it during the migration seasons following
the completion of the Brewery fish pass.
GUNDRY'S WEIR (before):
The project to install the fish pass was the result of collaboration between the Environment Agency (who own the weir),
Friends of Rivers, Frome, Piddle & West Country Fisheries' Association and Westcountry Rivers Trust. A Programme Board
was set up with representatives from each of these bodies to oversee the project which was managed and funded by the
Environment Agency. Work commenced in the autumn of 2013 and was completed in August 2014.
GUNDRY'S WEIR (after):
A single flight Larinier fish pass has been installed within the weir against the right bank wall with a separate integral
eel pass. Construction involved a series of angled stainless steel plates set into a concrete ramp to disturb flows and
allow the fish to climb it. The toe of the existing weir is tied into the entrance (downstream part) of the new pass. This
is to ensure the attraction flow to the fish to ensure they can find the pass as they approach the weir. This will result
in the Larinier pass extending approximately 10 metres upstream of the existing weir crest.
A new single-span footbridge was also constructed as part of the works.
With the completion of the fish pass at Gundry's migratory fish are now able to navigate the river Brit all the way from
the sea at West Bay, past the Brewery hatches, over Gundry's Weir, past Pymore Weir to the weir at Slape Manor. They now
have access to some eight kilometres of ideal habitat of spawning habitat above Gundry's Weir.
Armed with this knowledge we took ourselves off to the Loders Arms for a celebratory lunch!
Previous walks - 2009 and earlier