Bidwell Brook – a foul water story…

If you wander from the bus stop in Dartington opposite the village shop and walk towards Things Happen Here you will pass one of the four most vital bits of infrastructure in the village.
Because running by the Wave Academy school, under the road and emerging by the Cider Press Centre is the Bidwell Brook, a six mile stream which has become polluted thanks to the five sewage outfalls which discharge into it. And one of these CSOs – combined sewage outfalls – is tucked away behind the patch of village green where you can sit on one of the benches and watch the world go by.

As we know, nationally all is not well with our rivers. Thousands of times a year, massive quantities of storm water overflows are pumped into them when the drains are overwhelmed with rainwater – and because the old drains also carry our household effluent (hence combined sewage outfalls) – that unlovely mix goes with it….polluting rivers and beaches. The Bidwell Brook’s valley is an important wildlife corridor, supporting many species, including otters and bats. It connects several wildlife sites, including ancient woodland, bat roosts and existing and planned conservation projects. A year ago the Bidwell Brook Partnership was set up to push for a clean up. The Partnership includes Dartington Parish Council, Rattery Parish Council, The Friends of the Dart, the Dartington Recreation Association, Dartington Hall Trust and The Apricot Centre.

I spoke to Richard Haigh, from Rattery Parish Council, about the partnership’s long term plans to clean up the brook. “We have done two things. One is to put farmers at the forefront of what we are doing and the other is to get South West Water involved.”

HEALTH CONCERNS

The brook discharges into the Dart right by a popular canoeing and bathing spot and in 2022 around 200 people reported falling ill after swimming in the river. “Microbial pollution is a threat to human health more than it is to wildlife – hence it is the major concern for Friends of the Dart and their campaign to achieve bathing quality water for the Dart,” said Richard.

Bidwell brook, which rises in Rattery, is classified as having only “moderate ecological status” because the untreated sewage contributes to the level of phosphates in the water, and phosphates impact on the plant life in the brook.

In 2022, there were 299 spills to the Bidwell Brook totalling 2,990 hours (124 days). That was just from the five outfalls (all of which spilled) with Event Duration Monitoring installed. And that was in a particularly dry year. Three of these outfalls (1 in Rattery and 2 in Dartington) are in the top 10% sites for total duration of spill for South West Water. The monitoring shows that the sources are poor livestock management, poor soil management and poor nutrient management – run off from fields gets into the drains – but the worst offender was the waste water treatment plant in Rattery.

The 13 sq km catchment area of the Bidwell Brook has about 20 farms, including two dairy farms, vegetable and arable, lamb and beef, Richard said. There’s now a concerted effort to help farms get grants to make their farms more sensitive to the needs of the catchment, he said. SWW, the Westcountry Rivers Trust and the Devon Wildlife Trust are all involved. Pesticides, slurry and fertilisers make agricultural run off a big problem.

SWW’s website includes this nugget of information: “In terms of bacteria, one cow has the pollution potential of 50 people. There are roughly 850,000 cows in Devon and Cornwall.” Richard said: ”This is a ten to twenty year project and the key is this has to be a farm led project. Farms are in dire straits at the moment and they need all the help they can get.”

Farmer Peter Smerdon, who farms beef and sheep in the area and is on Rattery Parish Council, said half his farm is already involved in the catchment sensitive farming scheme and he welcomed this being extended to the Bidwell Brook catchment. “You can’t stop cattle grazing. It’s when they are housed indoors and the muck is in one place, then you have the possibility of run off from the yards and storage areas.” “Everybody is well aware of the problem and has a duty of care to make sure your system doesn’t cause pollution.” Solutions include building more storage tanks, aerating the fields to let more water drain through and stopping cows wading into streams to drink – and relieve themselves.

The main problem though is the discharge from the Combined Sewage Outfalls. Investigations by South West Water have found that what is also getting into the drains includes dog poo, bird poo and road dirt. This has been confirmed by DNA testing, Richard told me. There may also be some run off from private sewage soakaways.

Climate change is not helping. Heavier rain means the old drains are overwhelmed more often than they were. More hard surfaces as homes are built means more water runs into them rather than sinking into the ground.  As Richard points out, these discharges should only be in emergencies, but in 2023 there were 98 incidents at the school CSO, compared to 61 in 2020.

Which is why SWW is looking at using nature based systems, sustainable drainage systems, water butts and soakaways. In a statement SWW said: ”Although our plans are still in development, a solution has been developed to reduce spills to fewer than 10 a year and fewer than three per bathing season. This is likely to include the creation of storage tanks, relining or rehabilitation of several sections of the network, changes to the network to reduce reliance on storm overflows and other measures that reduce both infiltration and inflow to our network from the surrounding landscape and private networks in the village.”

BEWARE A FATBERG

And apparently locals aren’t helping by shoving old cooking oil down the sink and throwing wipes down the loo. SWW said: ”These materials have been responsible for causing blockages and other waste-water issues in Dartington over recent months.” You have been told!

I understand the homes now being built in Dartington are on a twin system so all the sewerage goes straight to the Totnes treatment works.

It is going to take years and lots of money to solve the problem and bring the brook back to full health, which will benefit the Dart and its users and the wildlife which lives in the beautiful Bidwell valley.