The 11th Dartmoor Society Debate
What Future for Dartmoor’s Water Resources?
27th September 2008, Meldon Village Hall
© The Dartmoor Society, 2008
Fifty-five delegates and speakers, under the chairmanship of Paul Gompertz, Director of Devon Wildlife Trust, gathered in the splendid Meldon Village Hall to discuss Dartmoor’s water resources.
The first speaker was Mike Hedges (Dartmoor Society member and recently retired Planning & Capital Works Manager of Portsmouth Water) who covered ‘The History of Dartmoor’s Water Resources’ in a richly illustrated talk.
Mike explored a wide range of uses of Dartmoor’s water from earliest times when the first settlers required a supply of water for their own survival, as well as that of their grazing animals. He used the example of Grimspound which enclosed part of the stream known as Grim’s Lake, a tributary of the West Webburn.
Water played an integral part in the viability of hundreds of years of mining operations on Dartmoor for tin, copper, lead, silver, zinc, arsenic, iron, tungsten and uranium. Waterwheels, which were more or less common to all mines, were used for:-
a) driving stamps to crush the excavated ore into finer particles.
b) driving bellows to force air through the smelting furnaces.
c) driving other equipment, e.g. pumps
d) operating buddles for settling crushed tin
The steeply falling river valleys of Dartmoor were suited to the widespread use of leats, and many of these were built to convey water from rivers and streams to the sites of workings. They followed a gradually descending route, following the contours where necessary or feasible, and were often constructed over long distances. Examples included the Birch Tor & Vitifer Mine Leat, the Grimstone & Sortridge Leat and the Wheal Emma Leat. The latter was built in 1859 to augment the waters of the River Mardle, which in turn provided power at the Wheal Emma (later Brookwood) Copper Mine, near Buckfastleigh. It was approximately 8 miles long and its remains are clearly visible today over much of its route.
Occasionally, at workings located some way from, or too high above, a river valley, reservoirs were constructed to collect and store rainwater from channels to supply such workings.
Mike then took the example of Wheal Frederick (Foxhole) Mine, which was located in the valley of the Doe Tor Brook, western Dartmoor. The mine was licensed in 1845, and is recorded as having produced £200 - £300 worth of tin in 1865. It employed 12 to 15 men at most and the sett was abandoned in 1887 (ref: Wheal Frederick Tin Mine – Doe Tor Brook, by Tom Greeves, Dartmoor Magazine no. 73). The site of Wheal Frederick (grid ref SX 546 854) contains to this day a number of interesting features that bear testimony to the essential use of water in the process. These features include:-
• a leat
• an elevated leat embankment
• a filled-in waterwheel pit (the waterwheel drove the stamps that crushed the tin ore).
• two buddles, i.e. shallow circular settling tanks in which tin-bearing sand was built up as a deposit while lighter, non-metal bearing material was washed away.
Mike showed slides of the Kelly Mine, near Lustleigh, restored by the Kelly Mine Preservation Society. This mine produced micaceous haematite (for anti-corrosion paints) between 1797 – 1951. The mine includes a working waterwheel, which drives numerous items of equipment including a set of stamps.
The need for water on farms, both for domestic use and for livestock, was covered next. Mike showed aerial views of Manga Farm (North Teign), where it is still possible to trace the course of the leat supplying the farm from Manga Brook, and Teignhead Farm (North Teign) located close to the same brook. At each farm, one can still see small water troughs among the ruins.
As well as its use in the mining of metal ore, water had a vital role in the powering of corn mills, of which one of the earliest known examples is at Babeny, dating from about 1304. Other such mills existed at Jordan (Widecombe), Sandypark (Chagford), Higher Batworthy (south of Chagford), Rushford (Chagford), Gidleigh and Peter Tavy Higher Mill, to name but a few.
Water power also drove fulling (tucking) mills for pounding and cleaning wool. Examples were at Chagford (1800), Buckfast (12th century onwards) and Buckfastleigh (Town Mill, 1846).
Paper production, relying on water, was practised at Shaugh Prior, South Brent, Moretonhampstead, Buckfastleigh and Horrabridge. At Ivybridge, paper is still produced by Arjo Wiggins Fine Papers Ltd at Stowford Mill. This paper is used for passports, driving licences, cheques etc., and the mill employed 150 people in 2000.
The unique works at Powdermills near Postbridge (operating from 1844 – c. 1900) produced gunpowder. The constituents were ground to fine particles at a series of water-driven mills.
Dartmoor’s water was harnessed for hydro-electric power at Chagford (1891), Mary Tavy (1936), and at many smaller installations. Modern small-scale hydro plants exist on Dartmoor today and there is much potential for further installations. A prime example is that of Miles and Gail Fursdon at Old Walls Farm, Poundsgate, where the annual average output is enough to supply 90 houses, and where surplus electricity is sold to the grid. The installation paid for itself in 4½ years.
Mike then focused on china clay production. The operational china clay sites on Dartmoor are at Lee Mill (Imerys) and Cornwood (WBB). The Lee Moor works were started by John Dickens & John Cawley in 1830, taken over by William Phillips in 1833 and by Martin Brothers in 1862. By the 1870s there were nine clay works from Cadover Bridge to Crownhill Down and Headon Down, and on the lower slopes of Penn Beacon and Wotter. English Clays Lovering Pochin took over the site in 1932, followed by English China Clays, then later Imerys.
Water in powerful jets is used to wash out china clay and transport it via pumping to settling pits. Water is supplied from the former Bottle Hill Mine Leat which runs for 4 miles from Ditsworthy Weir on the Plym, via Trowlesworthy Warren to Lee Moor. Supplies are augmented by other sources from Penn Beacon and the Tory Brook.
China clay is cleaned and flows as slurry to drying works at Marsh Mills.180 people were employed in 2004 at the site, which occupies 2,200 acres. The capacity is 300,000 tonnes per year.
Other china clay sites on Dartmoor include
• Knattabarrow Pool (1836)
• Bala Brook (1858)
• Petre’s Pit and Shipley Bridge (1850s and 1870s)
• Leftlake (19th century and 1922 – 1932 with Red Lake)
• Red Lake (1910 – 1932) employed up to 100 men (and one lady – the mine captain’s wife in charge of the hostel!)
Mike showed slides of the Red Lake works in its operational days and in the present day.
Local leats on Dartmoor formed the earliest, very localised supplies. In fact, many properties on Dartmoor still take their supplies from leats and treat the water in private package plants. The best known leats are
• Plymouth Leat 1591. Sir Francis Drake was on the Select Committee that approved the Bill and he carried out the contract at a profit of £140. The Leat took water from the River Meavy at Burrator (the site of the future reservoir) to Plymouth. It supplied houses and businesses including corn and other mills.
• Devonport Leat 1797. Built to supply the growing needs of Plymouth Dock, it takes water from the Blackbrook, Cowsic and West Dart rivers.
The major use of Dartmoor for water supply has developed since the mid-19th century. The principal public water supply sources (with opening dates) on Dartmoor are Tottiford Reservoir (1861), Kennick Reservoir (1884), Trenchford Reservoir (1907), South Teign Intake (1927) and Fernworthy Reservoir (1942) all supplying Torquay, and
Venford Reservoir (1907) and Swincombe Intake (1929), supplying Paignton. Avon Reservoir (1957), supplies south Devon. Burrator Reservoir (1898, extended in 1928), supplies Plymouth. Prewley Intake (1952), Taw Marsh (1959, now closed) and Meldon Reservoir (1972) supplies north Devon.
Mike looked in more detail at Fernworthy Reservoir, of which the summary history is as follows:
• intake on South Teign built in 1927 (Edward Sandeman was the Engineer) to augment water supply to Torquay, when a ‘splendid site’ for a future dam was noted.
• water gravitated via a 16-inch pipe to Kennick/Tottiford/Trenchford.
• 999 year lease from Duchy of Cornwall.
• area was being planted with conifers for what became Fernworthy Forest.
• Fernworthy Farm was abandoned and partly demolished.
• powers to build the reservoir were obtained in 1934 (Edward Sandeman was again the Engineer).
• contract was let in 1936 to A. Waddington & Son of Sheffield.
• construction was straightforward except for a deep mineral vein, which had to be excavated and filled with concrete.
• 4th Aug 1938: 3.47 inches of rain fell in 8 hours – 2 million gallons of water and 500 cubic yards of material had to be removed from the workings.
• an overhead cableway, tipping trucks, overlapping derricks and a 2ft gauge railway system were used to remove excavated material from the dam foundations, and to move materials such as concrete and dressed stone into the required position.
Edward Sandeman (1862 – 1959) began a water engineering dynasty, which was heavily involved in water supply on Dartmoor. His life and career can briefly be summarised thus:-
• Water Engineer, City of Plymouth (1891 – 1900).
• Engineer to the Derwent Valley Water Board (1900 – 1912).
• formed own consultancy, E. Sandeman & Partners (1912 - 1939).
• ‘almost’ knighted for work at Derwent Valley. Apparently King George V was annoyed at a press leak about a forthcoming knighthood for Sandeman, refused to attend the opening ceremony at Derwent Valley, and consequently the knighthood fell by the wayside!
• involved in early water engineering in Egypt.
• from a Quaker family in north-east England.
• worked until he was 77!
• lived at Shaldon, Teignmouth in retirement.
• highly respected water engineer of his time.
• consultancy changed its name to Sandeman, Kennard & Partners (1939 – 1970), when Julius Kennard, who had carried out the detailed design for Fernworthy, became a partner in Sandeman’s business.
• this firm merged with Rofe & Raffety in 1970 to form Rofe, Kennard & Lapworth (1970- 1997). Julius Kennard’s son Michael became a partner.
• this relatively small, but expert firm of consultants designed many water supply schemes, both in the UK and (later) overseas
• thus Sandeman himself worked on the early Dartmoor reservoirs and his successor partners designed Meldon, the last one to be built on Dartmoor.
In conclusion, Mike stressed that due to Dartmoor’s valuable water resources :
• productive water-reliant industries have been developed and operated over many centuries.
• employment has been provided for many local people.
• alternative employment and production has been available in an area where the climate is not sympathetic to agriculture.
• essential public water supplies continue to be provided.
• great scope is offered for renewable energy in the form of hydropower and several successful schemes have been implemented in recent years.
The second speaker was Chris Elliott of Western Renewable Energy Ltd, who spoke on ‘The Use and Future Development of Hydropower on Dartmoor’.
He reminded us that before the industrial revolution ‘water was king’. On Dartmoor mills are recorded from the 14th century, mostly for milling grain. Only a tiny number are still in use. Mining was also an important user of waterpower, for tin blowing houses and later machinery. Woollen mills, paper mills, forges and foundries were all important.
Hydro-electricity developed from the late 19th century. Rain falling above Chagford passed through 8 hydro-electric systems in the 1940s, as well as at least 7 mills. About 12 hydro-electric systems are in use currently on Dartmoor. Some reservoirs for water supply have hydro-power capacity.
The Christy brothers developed the Morwellham and Mary Tavy (the biggest in England) schemes. These two plants represent the bulk of the current hydro capacity on Dartmoor. Privately owned schemes exist at Buckfast Abbey, Sowton Mills, Old Walls and at Dart Country Park. Hydroschemes are hardly visible in the landscape, unlike reservoir dams.
Chris reminded us of renewable energy targets in the county, and capacity on Dartmoor:
• 2010 total Devon target : 151MW
• New Hydro capacity in the DNPA plan : 1.5MW
• Existing hydro capacity on Dartmoor : 3MW
• Total hydro capacity on Dartmoor : 7MW
• Approx Dartmoor mean electricity demand 10MW
So, Dartmoor has the potential to be almost self-sufficient in its electricty energy generation. But, remember:
• we’re just talking about electricity, not all fuels
• the hydro schemes on average may produce about 50% of their peak power output
• to develop 7MW would require harnessing of many rivers – is this acceptable?
• the proportion of water available for hydropower is being squeezed by new regulations
• BUT – new schemes are being approved, they are viable and they are, on balance, a good thing.
Chris then raised some very thought-provoking questions. He asked if Dartmoor is unspoilt? If it is, are we proud of that? Is it because of how we live our lives or despite how we live our lives? – he believes the latter. Can we sustain the current situation for ever? He felt that what is ‘good for the environment’ will become increasingly difficult to decide. He told us that the average person in the UK requires 25,000 units equivalent per capita per annum of energy. Just 1 unit is the energy required to carry 40 bags of sugar from sea level to the summit of Everest! 98% of our energy comes from oil, gas, coal, and nuclear, with only 2% renewable.
He told us that UK average annual car mileage is 15,000 miles. At 32 mpg this represents 2,100 litres of fuel at a cost of £2500. But where has this fuel come from? The top oil exporters are Saudi Arabia, Russia, Norway, Iran, UAE, Venezuela, Kuwait, Nigeria, Algeria, Mexico, Libya, Iraq, Angola and Kazakhstan. He wondered how many of us had been to these countries. What happens to the money that pays for this fuel? – there is no traceability. Yet the market is a dangerous thing and our £2500 can cause a lot of environmental damage. We are urged to ‘buy local’ for food – why not energy too?
Local decisions have a global impact, and other people’s decisions affect us locally. Most importantly, we can’t export our impacts and problems for ever - just because we don’t dig big holes in the ground on Dartmoor much any more, doesn’t mean it doesn’t happen somewhere, to some otherwise worthwhile habitat, in our name to satisfy our needs. Dartmoor gives a false sense of security that we are not having a big impact. Look, for example, at carbon emissions. Economic development depends on increasing carbon emissions. The Government claims a reduction in CO2 of 13% in the UK since 1990, but imports actually have caused a 13% rise. In Chris’s view, we haven’t even started to get the problem under control.
Regarding hydropower on Dartmoor, planning permission was possibly the biggest issue in past, but DNPA have better knowledge and fewer misconceptions now, and even some positive policies.
Regarding abstraction, the Environment Agency is the absolute key to determining the viability of schemes, but the EA is driven very strongly by the new Habitats Directive.
Chris stressed that the situation and ecosystems were highly complex and that it can be ‘very difficult to define what an impact is’. Some interests become of over-riding importance, and we therefore lose any balance in weighing up the evidence. Nowadays, ‘nothing is as important as salmon’ which distorts decision-making. There is still a lack of observed evidence.
So some key issues remain:
• how do you balance a non-financial ecological effect with a cut-and-dried economic decision?
• due to historical reasons, current roles and new regulations, salmon are above any balanced decision – they are given absolute priority .
• as viability improves, ‘best practice’ will keep on ratcheting up, but at some point this stops having any worthwhile effect.
• there is a need to acknowledge that both the EA and the hydropower industry believe they are ‘doing the right thing’.
• fish protection in terms of keeping them out of turbines is an issue which has been solved technically and ecologically.
• current tension relies on behavioural aspects of fish, i.e. will a fish be stimulated to attempt something? Will a fish behave differently after a certain event? This is hard to prove either way, and expensive to do so. Thus, the precautionary principle is adopted and becomes an issue, which is immensely frustrating for the operator who can demonstrate no evidence of a problem, but is told they may be causing a problem.
In looking to the future, Chris concluded that energy price increases will continue to make more sites viable, especially old sites such as Castle Drogo. The EA are seeking to reduce existing output, but they need to produce evidence of harm. New run-of-river sites will be proposed and approved on the fringes of the moor in the region of 50 – 200kW capacity, but complex abstraction regimes will develop in response to EA requirements, which will squeeze some of the smaller schemes.
After coffee, with scones and biscuits, the third speaker of the day was Simon Bates Senior Project Manager of Natural England whose talk was titled ‘Stugged in a mire - what is the future for Dartmoor’s wetlands?
Simon began with an extract from a poem, Dartmoor Days, by Edward Davis (1863), illustrating one perception of Dartmoor’s bogs:
’The hunter homeward speeds in haste,
Ere fogs o'ertake him on the waste;
And if to Foxtor mires he roam,
He'll bid a long adieu to home;
A dreary shroud is o'er his head,
A yawning swamp around him spread;
Spell-bound and lost he ventures on
One fatal step - and all is done’
As a result of the work of Chris Caseldine and Jackie Hatton, we now know that by about 7,700 BP [= Before Present] all the major tree species were established on Dartmoor: hazel, oak, birch, elm, alder. A landscape can be imagined with isolated pockets of heath on the highest exposed tor summits, a tree line characterised by hazel with some oak and birch, and a dominant woodland cover of oak with hazel and alder, the latter especially in river valleys.
Between 7,700 & 6,300 BP, there is a continuous record of microscopic charcoal paralleled by a gradual reduction in tree pollen and the expansion of peat-forming plants. This has been interpreted as the use of fire by Mesolithic man at the woodland edge as a strategy for hunting game, gradually reducing the tree line. Woodland regeneration was prevented by browsing, but more effective precipitation (rainfall) was the principal driver of blanket bog expansion.
Peat is the partially decomposed remains of plants laid down in waterlogged conditions. Sphagnum moss is more resistant to decay than other plants and when the rate of decay is less than the rate of accumulation, bogs & fens are formed. Under optimal conditions peat accumulates at 2mm per annum on average.
Blanket bogs receive all their water and nutrients from rain and clouds. They have a pH <4, and low levels of calcium & magnesium. Farmers call bog asphodel ‘brittle bone’ because prior to mineral supplements, sheep grazing where it occurred often suffered leg breaks, owing to the calcium deficiency. By contrast, fens receive more of their water and nutrients from the ground and, where springlines emerge from the edge of the granite, they are less acidic and richer in minerals.
Simon then suggested, with a demonstration involving a bucket of water and a sponge, that the popular notion of Dartmoor as a giant sponge, slowly releasing water, needs qualification. When the sponge is saturated water trickles out. If rainfall occurs, the response (i.e. release of water) is immediate. The ‘sponge myth’ leads to the mistaken assumption that bogs provide base flow during water shortage, and attenuate flooding. In fact, poor base flow can be a problem for water companies, despite 80% water being within 40cm of the peat surface for most of the year.
Good soil structure is vital for retention of water. Erik Meyles (Plymouth University) studied runoff from the catchment above Fernworthy reservoir. Below 60% soil moisture, there was minimal increase in stream discharge but above 60% there was a spike in runoff. Soil porosity below heavily grazed vegetation was 10-15% less than under vegetation with low grazing levels, giving rise to higher rainfall-runoff response in wet conditions and lower flows in dry conditions. This could have a negative impact on water supply in summer and flooding in winter. Therefore there was benefit in restoring heath because it reduces the possibility of a ‘flood pulse’.
The structure of peat is composed of two layers. The top 5-25cm has a fluctuating water level and high conductivity. Underlying this is an almost saturated layer. Many peatlands appear dominated by overland flow of water or through - flow in this upper peat layer when saturated. However, Dr Joseph Holden from Leeds University has recently discovered pipes & pores in the peat, through which about 10% of the water flows, moving up and down from the mineral soil. Drained peatlands have higher densities of pipes & gully erosion. Simon illustrated Cut Hill as an example of gully erosion.
Every six years the condition of Dartmoor vegetation is monitored.
The condition of bog & fen vegetation within Sites of Special Scientific Interest on Dartmoor as at March 2008 was 25% ‘favourable’, 25% ‘not favourable’, and 50% ‘unfavourable but recovering’. The major cause of unfavourable condition is uncontrolled fires.
Organic soils are a vast store of carbon. Dartmoor peat is the equivalent of 60 years of greenhouse gas emissions from Devon! 70% of our drinking water comes from the uplands.
What can we expect from climate change? The Government wants to reduce greenhouse gases so that we can avoid a 2°C global average increase in temperature. Global emission trends have risen from a 2.7% per annum average for the last 100 years to 3.3% per annum in the last 5 years – the Stern Report assumed 0.96%!. Minimising the rise to 4°C (which is the likely figure worldwide) requires a 3% annual reduction in CO2 equivalents. The only example where this has been met to date was following the collapse of the Soviet Union, when there was a 5% annual reduction.
In future, we can therefore expect that summer droughts will impact on small upland reservoirs and headwater streams which are
likely to experience lower flows and higher temperatures. Intense rain storms will increase peat loss. This peat will end up in the water supply. Yorkshire Water spend £30k per day to take out peat colouration! Structural changes to peat will follow drought. Mineralisation of nitrogen & sulphur will increase stream acidification. Oxidation of peat will release CO2. A loss of 2mm of global peat = 1.6 billion tonnes of CO2 = 8% annual global fossil fuel release.
How should we respond? Peatland restoration schemes are underway on Exmoor (Exmoor Mire Project) and on Dartmoor (on the Rattlebrook). They have proved an ‘instant success’ in terms of raising water levels. We might need to create more shallow pools within the peat areas.
We need to explain the importance of peat to ‘the more enlightened farmers’, who can then spread the word to others. Full benefits need to be costed and good management rewarded. Natural England hopes peer pressure will eventually bring an end to uncontrolled burning, which is still favoured by some farmers wanting to follow ‘traditional’ burning practice. Strategic firebreaks will become more important.
In mid-Wales, woodchip from new farm woodlands is being used for bedding, saving £50k per year per farm on straw purchase. Of course, the woodchip is also a fuel. Such savings make a massive difference for marginal upland farms. Planting of streamside and mid slope woodland areas and pond creation in previously drained areas has been shown to reduce surface runoff and increase infiltration, thus contributing to reduced flood peaks. One study calculates that the world's farm ponds bury more organic carbon than the oceans!
In conclusion, Simon said that Dartmoor’s bogs and fens formed under a cooler climate, and we still do not fully understand them. However, while their condition has improved in the last 10 years, climate change is a major threat. Blanket bog will probably not survive on Dartmoor but some fens might. Meanwhile, they are so important to us that we must do all we can to restore them. His talk ended with a more optimistic quotation from Miser’s Money by Eden Phillpotts (1920):
‘Only at clear dawns and sunsets will Fox Tor Mire sound its highest colour song, brim with delicate and transient brightness, shine through all its granite reeves and clitters, and blush over its moss bogs where the sphagna glow ivory white, emerald green and wine purple’.
A joint presentation came next, titled ‘The significance of the Habitats Directive for Dartmoor’, by two representatives of the Environment Agency: Emma-Rose Herrera, Team Leader, Technical (Fisheries, Recreation and Biodiversity), Devon, and Karen Gowlett, Senior Environmental Planning Officer, Devon & Cornwall.
Emma began by saying that the Habitats Directive was ‘not about stopping things’, but was about ‘balancing people and wildlife’, and was actually very positive. She explained that the Habitats Directive was a product of two directives, one in 1992 and one in 1979, plus regulations dating to 1994:
Š Council Directive 92/43/EEC on the conservation of natural habitats and of wild fauna and flora
Š Council Directive 79/409/EEC on the conservation of wild birds
Š Conservation (Natural Habitats, &c.) Regulations 1994
The Natura 2000 Network of protected sites included
Special Areas of Conservation (SACs), which are essentially habitats, and Special Protection Areas (SPAs) which relate to bird species. There are 325 SACs in England & Wales, and 100 SPAs, most of which are already SSSIs. In Devon and Cornwall there are 36 SACs and SPAs.
The overarching aim is to maintain and restore sites to a ‘Favourable Conservation Status’.’ Competent Authorities’ have a general duty, in the exercise of any of their functions, to have regard to the Habitats Directive. There is a requirement for ‘Appropriate Assessment’ of implications for sites of any ‘plan or project’ likely to have a significant effect (alone and in combination). The ‘Precautionary Principle’ is practised. Under ‘Plans and Projects’ the Environment Agency covers
Š Flood Risk Management
Š Discharge consents
Š Abstraction licences
Š Flood Defence Consents
Š Environmental Permitting Regs
Š Section 30 Consents (fish stocking)
Š Strategic Plans and Strategies
The largest undertaking is the ‘Review of Consents’ (RoC) which requires assessment of all existing consents for abstraction of water, with a deadline of 2010 imposed by DEFRA. There are about 250,000 permissions potentially affecting SACs and SPAs in England and Wales. The review is a 4-stage process:
Stage 1 – Identify relevant permissions
Stage 2 – Assess likely significance
Stage 3 – Appropriate Assessment
Stage 4 – Options Appraisal
Much of Dartmoor is a SAC, with boundaries that coincide with existing six SSSIs. Of particular interest are:
Northern Atlantic wet heath
Old sessile oakwoods
Of these, salmon are the key feature of the Dartmoor SAC.
Some 6,500 permissions relate to the Dartmoor SAC, of which there are 713 discharge consents and 62 abstraction licences which are ‘likely to have a significant effect’.
The presence of salmon in the Dartmoor SAC is confirmed by using historical records and electrofishing surveys. The ‘main stem’ of each river is assessed, not every tributary.
The Assessment at Stage 3 involved, in consultation with
Natural England, Dartmoor National Park, Hydrology & Fisheries:
• estimation & verification of natural flow at each of the assessment points.
• licensed impact of abstraction on natural flow.
• comparison of impacted flow with targeted flow.
Target flows are required to protect both the spawning and juvenile habitats within the SAC, plus the migration route to these areas.
Optimum flows for adult migration vary depending on location and the time of year. Considered are:
In Stage 4, decisions will be based on the best available information and science. The EA makes sure that views are obtained from stakeholders (including licence holders) including, in particular, Natural England. At the end of Stage 4 decisions are recorded and then licences are confirmed, modified or revoked.
A final decision will be recorded in the Site Action Plan for Dartmoor SAC at the end of the Stage 4 process. The Environment Agency is confident that decisions are made using the best available science and are fair and reasonable.
Regarding Stakeholder Engagement, the process is not consultative like Catchment Abstraction Management Strategies (CAMS), and the EA is unable to discuss potential modifications of revocations in an open forum, except with those who may be affected by permission changes. Factsheets are published, which are circulated to people and organisations in the interests of good relations and good practice. Some commercially sensitive information may be removed from the Stage 3 documents, if requested.
The Environment Agency commissioned a report (covering data 1992-2007) by the University of Hull International Fisheries Institute (HIFI), to investigate the status of Dartmoor SAC salmon populations, to meet reporting requirements for the Habitats Directive. The conclusion was that the Dartmoor SAC is in ‘unfavourable, declining condition for salmon’.
However, it should be mentioned that the conclusion says also that there are not as many salmon present in the SAC as would be expected under natural conditions, and the reduced numbers may be a result of many influencing factors such as climate change, sea survival or habitat condition (run-off, pollution etc). There was no evidence that this unfavourable, declining condition was a result of Environment Agency Abstraction licences.
We are moving forward on the precautionary principle to restrict abstraction to current levels. Further investigations will continue to monitor the salmon stocks and recruitment. Additional fish screening will also be put into place where required.
First Discussion Session
Quentin Morgan-Edwards raised Chris Elliott’s point about an overemphasis on salmon [Chris Elliott had had to leave to go to a wedding!]. Emma-Rose Herrera emphasised that the EA supports renewable energy, but not at the cost of what makes rivers special. Salmon are indicators of a healthy system, or otherwise. The EA does not want to prevent hydropower, and the fact that Dartmoor has hydropower and salmon on the same rivers is proof of that.
Judy Ehlen said she was from the Pacific North-West which was major salmon country. Why was there this emphasis on salmon? What about trout? Emma-Rose Herrera said that salmon were the key indicator species.
Major Montague said that he represented a good many fishing interests, including those on the R. Teign. There was a need to get the right balance between hydro schemes and fisheries. How will EA control hydro schemes and monitor the amount of water abstracted? Karen Gowlett said that EA were specially interested in the ‘deprived reach’ (between abstraction of water and its return to the river) relating to hydro schemes.
Edmund Marriage of British Wildlife Management said there was far too much red tape and bureaucracy. There needed to be a much closer link with farmers and wildlife practitioners. The reseeding of heather on a 7-year rotation in the Peak District was a good example of what was possible. In general, there was a ‘catastrophic’ situation of ‘undergrazing’. We must look to examples of where problems had been solved. Simon Bates agreed that it was vital that the agencies talked face to face with farmers. EM said that there was a real problem with badgers.
Paul Gompertz said that if 3% of wetland stores 30% of the world’s carbon, perhaps private ownership of wetland should be abolished.
Diana Moyse, a resident of Lydford said that South West Water had been looking for a site for a new sewage treatment works and required a ‘fast-flowing river’ so that effluent could be dispersed. E-RH said that this was an example of the very raison d’etre behind the Environment Agency.
Gail Fursdon wanted to know how many of the 62 abstraction licences being reviewed on Dartmoor were for hydro schemes. [information was found over lunch and the answer given by Karen Gowlett was that there were 6. GF asked if one of these was the Mary Tavy scheme, but was told this could not be revealed. GF asked that full details of any decision should be published].
GF also asked about the figures Simon Bates had quoted for woodchip as a substitute bedding material. She said that £50,000 represented 500 tons of straw, and she wondered how many acres of woodland would be required to produce an equivalent amount of woodchip bedding. SB said he would look into it.
Tom Greeves said that a cynic would look at the mire restoration project at Rattlebrook and say that its impact must be infinitesimal. He wondered whether existing pools within the blanket bog area had been studied for their effect on wetting the surrounding peat. He reminded the audience that the military used to create many small pools with their artillery shells. Might the restoration of Cranmere Pool be a good idea? Simon Bates said that the Rattlebrook scheme was a pilot project, covering 50 acres in total. Some research on pools in general had been carried out by Lauren Parry of Plymouth University.
The afternoon session began with Jeanette Collett, Ecological Appraisal Team Leader of the Environment Agency, talking on ‘Creating a Better Environment - The Health of Dartmoor Rivers’.
She began by telling the meeting about a significant piece of relatively new legislation, the Water Framework Directive (WFD), a European law which aims to deliver long-term protection of the water environment, with watercourses having a good ecological status. The Directive rewrites existing legislation into a new overarching programme, leading to effective and more sustainable water management. It has an ecological focus.
A wide range of monitoring is used, together with chemical and physical measures to assess the ecological status of waterbodies. From this will be developed River Basin Management Plans that will set how it is hoped to address problems and work towards achieving good ecological status. Draft plans are being worked on now and will be out for consultation at the end of this year
Two teams based at Exminster and Bodmin / Launceston undertake ecological sampling and analysis for the rivers on Dartmoor. Work is a mixture of field surveys, lab work and data analysis and reporting. The greatest challenge is to turn scientifically robust data gathered from fieldwork into information for a wide range of people.
Ecological assessment is done by using biological indicators:
h Benthic Invertebrates
h Macrophytes (plants and mosses)
h Other Surveys
h River Habitat Survey (RHS)
At this point, Kevin Baker of the EA demonstrated the core field toolkit of toothbrush, net and bucket.
Invertebrates are present all year round and respond to pollutants. They are sampled in spring and autumn, using 3 - minute kick samples and a 1 - minute hand search. Many of the 1000+ species have a range of tolerances to different types of environmental stress – e.g. organic, acidic, metals, pesticides. Stoneflies, Mayflies and Caddis flies are specially sensitive fauna and indicators of good water quality, found in highly oxygenated, fast flow, clean waters. They are dominant in Dartmoor rivers. Reasonably tolerant are Freshwater Shrimp, Blackfly Larvae and Water Beetles.
Gammarus and asellus ratios can help to indicate organic enrichment . Most tolerant are worms, most snails, non-biting midge larvae and leeches. When the community is out of balance, the tolerant species dominate.
Macrophytes and diatoms are also studied. The latter are unicellular algae in an ornamental silica case (frustule), distinct for each species. The Trophic Diatom Index (TDI) monitors eutrophication (organic enrichment).The diatoms are collected by scrubbing and chemical preparation, and then examined under a microscope
Fish are high up the food chain, so are good indicators of the overall health of our aquatic environment, and are the first to be impacted by rising river temperatures. They are very sensitive to stress. Fish surveys are undertaken of juvenile salmonid fish using electric fishing – no harm is done to the fish which are briefly drawn to the cathode, netted and then measured and identified.
The Tavy, Walkham, Lyd, Plym, Meavy, Piall and Yealm rivers all support salmon and sea trout. For the most part, they support good macroinvertebrate populations, though there are some localised pressures from industry. The Lyd is an excellent river and supports the highest densities of salmon on the Tamar catchment.
The Tavy is generally expected to attain good ecological status under the WFD, although it is at risk/probably at risk in certain parts of the catchment from acidification, hydrology, dangerous substances directive chemicals, diffuse sediment, mines, metals, pesticides, combined source phosphates and morphological changes to the watercourse. There are currently phosphate issues on the R. Burn, but these are being addressed and it is anticipated that by 2015 phosphate levels will not limit the ecology. Work is underway to improve the abstraction at Hillbridge and work has already been carried out to improve the screening of intakes to protect fish.
The Plym is also expected to attain good status, although the Tory Brook is not. China clay impacts in the headwaters are a limiting impact for fish and macroinvertebrate populations. Mines, dangerous substances directive chemicals, metals, and morphological changes are among the pressures acting upon this catchment.
The Yealm also has china clay impacts at the headwaters of the River Piall and although good for the most part, fish have only moderate status in places. The salmon run on the Yealm is small compared to the Plym, Lyd and Tavy but the Yealm supports a good run of sea trout. The Erme, Avon, Dart, Teign, Okement & Taw all support salmon and sea trout, and their health is good. They drain from Dartmoor within the Devon Area of the EA. These rivers all support salmon and sea trout and for the most part, support good macroinvertebrate and plant populations.
The major pressures on the health of the rivers include discharges from sewage works, ball clay extraction and mines. There is a naturally low pH, especially on the high moor. Abstractions may be a problem, as can be agricultural & diffuse sediment inputs which can cause smothering of gravels and increase of algal growth through nutrient input. Migratory barriers to fish which may be both natural & artificial can cause problems, as can a lack of spawning gravel where there is a naturally high occurrence of boulders and the substrate is very embedded.
In general it can be said that the fish populations on Dartmoor’s rivers are good, although high flow levels have made surveying difficult this year. The data has not highlighted any poor results and many of the sites surveyed within the Dartmoor SAC have had salmon present although typically in low numbers.
Annual samples of macroinvertebrates collected show good quality although monitoring has been reduced this year to only one site for operational reasons. Several samples have been collected as part of the Dartmoor SAC project but most are yet to be processed.
Dartmoor rivers contain a large component of mosses typical of these river types and can provide a good indication of the pH levels of the water. No major water quality issues have been identified.
Diatoms are particularly good at identifying nutrient issues. This can be a problem at sites where there is agricultural or diffuse inputs but generally results are good across the Dartmoor rivers.
Among concerns are invasive plant species such as Japanese Knotweed and Himalayan Balsam. Signal Crayfish and Top Mouth Gudgeon (from Asia) are also a problem. These species often out-compete native species, reduce habitat, and spread disease.
Future challenges include climate change, which will result in increasing river temperatures, and extreme & unpredictable weather – more droughts, more flood events; changes in land-use & farm practices; inability to manage habitats to benefit of wildlife.
Among anticipated changes are the warming of headwater streams, and the loss of temperature intolerant species. There is a predicted 20% decline in macroinvertebrate abundances per 1°C rise in temperature, and there is a predicted 2.5 °C increase in SW by 2050.
What does climate change mean for Dartmoor? Research by Durance and Ormerod (2007) found that macroinvertebrates in headwater streams at Llyn Brianne (Wales) were profoundly affected by increasing temperature over a 25 year period. Between 1981 and 2005 forest and moorland streams warmed respectively by 1.4 and 1.7 °C after accounting for the natural variability between years (North Atlantic Oscillation affects).
The species assemblage changed, as heat-intolerant species were lost. Although many core species could persist if temperature gain reached 3 °C, between 4 and 10 of the mostly scarce taxa, representing 5-12 per cent of the species pool, would risk local extinction. Perhaps more importantly, their studies showed that macroinvertebrate abundance might decline significantly with even small increases in temperature which are expected to occur by the 2050s. Durance predicted that in circumneutral streams, spring macroinvertebrate abundance might decline by 21 per cent for every 1°C rise in temperature.
The moorland streams of Bodmin Moor and Dartmoor offer a great opportunity to monitor ecological changes in an area of the country with even greater predicted gains in temperature. Under UKCIP 2002 high emissions scenarios, temperatures in South West England are predicted to increase by up to 2.5°C by 2050, which could have a considerable impact on freshwater ecology.
Work has started on 4 sites on the River Walkham, from the headwaters of Dartmoor to the confluence with the River Tavy, to see what is happening relative to climate change. We will be looking at invertebrates, fish, plants and diatoms and also collecting some chemical data. The range of sites have different land uses and varying degrees of shade. The sites are fairly evenly spaced to provide good coverage of the catchment and provide data from a range of altitudes and distances from river source. This will enable monitoring of the rate of ecological and temperature change over time within the headwaters, and comparison to sites further downstream as well. To keep costs to a minimum existing monitoring sites are used where possible. This also maximises the amount of historic data.
Headwaters are important because they are good indicators of environmental change; they are relatively unshaded, have high thermal stress; are small streams, reflect ambient air temperature; and are relatively unimpacted. Headwater streams are sensitive to environmental changes due to their altitude, lack of shading on moorlands and small size, which does not buffer the environmental temperature well. They are also not subject to all the other pressures acting upon the lower catchment. This makes them good indicators of environmental change.
A monitoring programme will show where the rate of ecological change over time is greatest. When looked at in relation to water temperature, land use and riparian management we can see where we need to prioritise our adaptation plans. We can also use the monitoring programme to see what effect land management strategies have on the ecology.
Adaptation measures might include promoting a higher sward height around the river corridor to shade the water, by protecting the riparian corridor from grazing. Planting more trees to provide shading is possible.
The data from this monitoring programme will also inform potential conflicts of riparian management, such as over-coppicing by angling clubs and deforestation of the riparian corridor for flood risk management, versus the ecological benefits of shading to cool the water temperature.
The final presentation was from Andy Hingston of South West Water: ‘The Impact of New Development on Dartmoor’s Water Resources’.
NB 1 megalitre (ML) = 1,000,000 litres.
The SWW Water Resources System is based on 3 strategic river regulating reservoirs, 14 smaller local reservoirs and 10% groundwater supplies. The three core reservoirs are Colliford, Roadford and Wimbleball. Roadford supplies north and south Devon via Northcombe in the north, Crownhill in Plymouth and Littlehempston in Totnes. It is the largest reservoir in the SW and In the summer can supply in excess of 150 ML into Devon.
Burrator stores 4500 ML and was built in the 1890s. It can supply up to 90 ML per day to Crownhill or Totnes. It was the principle supply for Plymouth until Roadford. The Avon reservoir was built in 1957 and holds 1360 ML. It supplies Avon Water Treatment Works which can produce 12 ML per day. Venford was built in the early 20th century and stores 850 ML. Fernworthy supplies up to 13 ML to Tottiford and Bovey Cross Water Treatment Works. It stores 1765 ML. The Kennick, Tottiford, Trenchford complex stores 2000 ML.
Tottiford Water Treatment Works treats up to 30 ML per day for supply to Newton Abbot and Teignmouth.
South West Hydro is a group of Hydro Power Stations situated on the western edge of Dartmoor. They consist of two power plants built by Christy Bros of Chelmsford from 1932 to 1936, along with an 11000-volt grid which brought electricity to the rural areas of West and North Devon. These hydro-electric plants were acquired by South West Water Ltd in 1996. Mary Tavy Power Station consists of two schemes:-
The first constructed in 1932, using an old mine leat 2 miles long
conveying water from the River Tavy, to a 1.5 million gallon storage reservoir,
and drives 3 x 230 KW Francis turbines, off a 220ft Head.
The second, built in 1936 with a 4 mile long old mine leat, takes water from the upper reaches of the Tavy to a 6 million gallon storage reservoir. The 560 ft head drives 3 x Pelton Wheel turbines each producing 650 KW.
Morwellham Power Station was constructed in 1934 and made use of the 4 mile long Tavistock Canal, which itself was started in 1803, to convey ore from the Mary Tavy mines and other goods to the inland port of Morwellham. At the end of the canal is a 1.5 million gallon reservoir and the head available of 240ft drives 2 x 320KW Turgo-Impulse turbines. South West Water Ltd are currently carrying out a major refurbishment programme to the Mary Tavy and Morwellham Power Stations, to secure their future long term operation and enable them to be accredited with OFGEM as generators of ‘renewable energy’.
The hydro staff also have the responsibility for the maintenance of the company's other hydro assets at Roadford, Meldon, Crownhill, Avon and Littlehempston. Hydro power is a renewable energy and as such helps to reduce the emissions of oxides of carbon, nitrogen and sulphur which are believed to be causing global warming, ozone depletion and acid rain. If the hydro operation were to be replaced with fossil fuelled generation (i.e. coal, oil and gas) then the emissions to atmosphere of these gases would increase by :
Carbon Dioxide 9129.4 tonnes per annum
Sulphur Dioxide 89.9 tonnes per annum
Oxides of Nitrogen 29.2 tonnes per annum
As can be seen the hydro operation, as well as being profitable, has a major environmental benefit, providing a good clean source of energy for the company.
The population within the SWW region (Cornwall, Devon and part of Dorset) has grown over the last 30 years from 1.36m to 1.65m today. By 2035 it is estimated to be 1.86m.
In England the temperature record goes back to 1659 and Andy said that he had lived through 9 of the 10 hottest years since 1659. You only need to be 57 to have lived through all 10 of the 10 hottest years. Without recourse to complicated statistics this indicates that something different is happening.
So how are we going to meet future demand for development like new towns such as those planned near Plymouth and Exeter? Recent investment has put SWW in a relatively good strategic position.
We are going to meet future growth via three main measures – metering (there has been a large uptake), leakage control (84 ML is considered an acceptable ‘economic’ level) and water efficiency. A 10% saving on domestic consumption; and savings of over 10% identified at 60%+ of audits of small and medium enterprises. At Waste Water Treatment Works 2300 ML per year of potable water is used, and 25% of this could be saved. The economics of these schemes looks very good.
An example of SWW meeting any supply demand gaps is the purchase of Park and Stannon Lakes in Cornwall, which are flooded old china clay workings This is a cost effective solution to close a supply demand gap in Cornwall. The purchase meant there is no need to develop more expensive solutions.
No new reservoirs are planned in the region up to 2035.
Final Discussion Session
Quentin Morgan-Edwards wanted to know if there were plans for a national grid for water. Andy Hingston said there weren’t any such plans at the moment.
Judy Ehlen asked if existing dams were going to be used for hydro generation and whether there were any new hydro schemes in the pipeline. AH said there no SWW plans for new schemes in the next few years but that they are looking at existing sites. E-RH said that the EA were really keen that this should happen.
Major Montague wanted to know if there were any plans to store winter water by raising the height of dams. AH said that SWW was already conserving winter rains.
Dinie Brickl asked whether salmon could get above Lydford Gorge. E-RH said no, the gorge was a barrier to salmon.
Diana Moyse questioned whether efficiency alone could guarantee a supply of water to the thousands of new homes mentioned in the Regional Spatial Strategy. AH said it could.
Kevin Baker said that some 24,000 new houses were predicted in the region, and questioned whether SWW might be underestimating the demand. AH replied that SWW had considerable flexibility in its supply.
Edmund Marriage said that he had recently attended a conference at which it was stated that the UK had the greatest problem, out of all European countries, in supplying water to its population. Increasing acidity of rivers was another issue, with some being considered ‘too clean’. Jeanette Collett said there were no problems regarding acidity, and that our rivers were not ‘too clean’ – she was saying this based on 29 years of experience in the field. EM queried how it was that in the 1920s and 1930s, with 28m sheep, liming and intensive farming, that stocks of river fish were at their height. JC said the salmon issue was complex and that factors in the oceans played a part too. E-RH said that much EA work was done on habitats, not fish.
Paul Gompertz urged everyone to read Unnatural History of the Sea by Callum Roberts. It included a concept of Diminishing Baselines, i.e. what was considered a yardstick of good condition in previous decades might be very different from present-day criteria.
Tom Greeves said that he had been encouraged to a certain extent by the positive messages coming from the EA and SWW, but felt that they did not square with the views expressed by Simon Bates of Natural England who predicted the loss of the blanket bogs of Dartmoor etc. Moreover, a fisherman friend (who has fished for many years on Dartmoor rivers) told him a few months ago that he was not going to bother renewing his licence as the fish stocks were so low (especially on the R. Dart). PG commented that Ofwat would not allow SWW to look beyond a narrow remit of activity. SB commented that NE has a timetable to 2080 compared to SWW’s target of 2035.
Gail Fursdon said there was an urgent need for the agencies to connect with people on the ground so that consultation reaches the sharp end of the real world. She and her husband, as farmers and owners of a hydro plant, had not seen their water bailiff for 8 months. JC said she was very concerned about this, and that it was a really good point. PG reminded everyone that it was our money that funded these agencies. SB asked what sort of communication was wanted, to which GF replied ‘we want to be listened to’. The Dartmoor Water Power Group were ‘teetering on the edge’, largely due to frustrations caused by the Habitats Directive.
Edmund Marriage said that there were about 450 organisations concerned with Countryside Management. He felt that the Dartmoor Society could lead the way on Dartmoor, with events such as this debate.
Major Montague said there was no shortage of water – it just fell at the wrong time. He felt we must store more water (e.g. by raising Wimbleball Dam) and we must pay more for water.
Speakers L-R: Simon Bates, Paul Gompertz, Emma-Rose Herrera, Karen Gowlett (kneeling), Jeanette Collett, Andy Hingston and Mike Hedges – Elisabeth Stanbrook
Paul Gompertz drew the day to a close by thanking all the speakers, and Tom Greeves invited everyone to thank PG very warmly for guiding the day so well, and he also asked everyone to thank Margaret Allin (of the Victorian Pantry, Okehampton) and her helpers for the first-class catering.