Data and Emerging Patterns, 2021


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This map shows where the three elements of the 2021 study were conducted. They are:
1 The River Parrett which forms the western boundary of Martock Parish
2 Wellhams Brook, known variously as Hinton Meads Brook and Hurst Brook in Martock, which drains into the Parrett, a wide area extending as far as Yeovil to the east.
3 Witcombe Bottom, mainly in Ash Parish, an artificially drained wetland around the River Yeo, a Parrett tributary.

Map of areas

Patterns emerging
The results of the survey are grouped geographically below into the three areas which are shown on the map. For detailed data of the three surveys, follow the links on the right

River Parrett in Martock Parish
The Parrett forms the western boundary of the Parish and samples have been taken throughout its length, from some tributaries as they enter the river on both banks, as well as from some adjacent ponds. The Parrett has a consistently high level of phosphate–around 1.0 ppm.. It serves to transport phosphate rather than a source of it. Under the winter drainage protocols this phosphate normally flows straight through to the Bristol Channel. Under the summer drainage protocols some of this nutrient rich water is diverted articicially onto the Moors and Levels.

Three sewage treatment plants drain into this stretch of the Parrett, South Petherton, Martock and Kingsbury Episcopi. None of these removes phosphate and they are a major source of the overall Parrett phosphate, possibly in excess of 30%.

Wellhams Brook, Martock Parish
Wellhams Brook is the name used by the Environment Agency to describe the system of tributaries that drain the western fringe of the Yeovil Scarpland east of Martock all of which converge to join the Parrett just upstream of Gawbridge. The main tributary is known locally as Hurst Brook (or Hinton Meads Brook) which divides shortly after entering the Parish creating a mill stream which once powered Madey Mill in Martock. The Mill stream (Mill Brook) rejoins Hurst Brook shortly before the confluence with the Parrett. The whole area contains a network or rhynes and ponds and is subject to frequent flooding. Phosphate levels are variable and linked to agriculture. No sewage treatment plants drain ino this system.

The Hills to Levels Scheme, Wellhams Brook
This scheme, developed by local and FWAG expertise, is an effective mechanism for controlling flooding of the village. It operates in various places in the Wellhams Brook catchment and has resulted in the creation of numbet of ponds of varying sizes throughout he catchment. Evidence is emerging that these can also play a significant part in removing nurients such as phosphate from the water through he growth of healthy oxgenating plans in and around the ponds. The ponds are also emerging as significant centres of biodivesity.

Witcombe Bottom and the River Yeo, Ash Parish
Witcombe Bottom is an area to the north in the parish of Ash. It is the floodplain of the River Yeo. It is now drained by a network of rhynes flowing into Witcombe Bottom Main Drain which is regulated by the pumping station on the Yeo at Long Load. It has always been an area of dairy farming which is now dominated by a large dairy (shortly to reach 3000 cows reportedly) which has, in turn, in the last few years, increaisingly dominated the agricultural rotations and farming practices in both Parishes.

There is a barrier across the Yeo at Long Load, adjacent to the pumping station, which is normaly raised in summer and lowered below the normal level in winter. This allows upstream farmers to access irrigation water in summer when the level is maintained high. Water is regularly pumped up from Witcombe Main Drain into the Yeo throughout the year, automatically controlled by the level of the Main Drain. Witcombe Main Drain is a major contributor to the phosphate pollution of the Yeo.

One small sewage treatment works, Tintinhull, feeds the Drain network. It does not have a phosphate removal stage yet. The measurements suggest that the impact of this plant is very small compared with that of agriculture of the area.

The River Yeo joins the Parrett downstream of both Parishes and some initial sampling has been done in Langport downstream of this confluence.


River Parrett survey
This shows consistetly high levels of phosphate throughout the year with the outflow from Martock Sewage Treatment works just north of Gawbridge consistently raising the level by between 10 and 20%.

Wellhams Brook survey
This showed considerable variation in phosphate levels, greatest during the winter when agricultural run-off was greatest. The impact of good watercourse management was noticable in several places.

Hills to Levels, Wellhams Brook
The potential of ths scheme to remove phosphate is discussed further here

Witcombe Bottom survey
This showed high levels of phosphate contamination of the waterways attributable to agricultural run-off. There was evidence of a spike during the spring slurry-speading season which was before the Levels drainage switched to summer mode and the Yeo was low. At this time, activating the Long Load pumps increased the phosphate concentration in the River Yeo by 25%