Natural and artificial landscapes merge on this route through wooded valley, heathy hill and across the mighty Wimbleball Dam.
Distance 6 miles (9.7km)
Minimum time 3hrs
Ascent/gradient 750ft (230m)
Level of difficulty Hard
Paths Rough descent, long climb, easy track between, 1 stile
Landscape Deeply wooded valley followed by airy, open heathland
Suggested map aqua3 OS Outdoor Leisure 9 Exmoor
Start/finish SS 969285
Dog friendliness Leads for short section past Haddon Hill Farm, no swimming (dogs or people)
Parking Frogwell Lodge car park, Haddon Hill
Public toilets At car park
© AA Media Limited 2015. © Crown Copyright Licence number 100021153
1 Leave the car park by a small gate 50yds (46m) to the left of the toilet block. Turn right to cross a tarred track, then head straight downhill on a small path. This runs down through gorse, grass and heather until open birch woods give rise to easier going. If you lose the path just keep going downhill. Just above the reservoir you meet a stony track.
2 Turn left on this. It emerges into open grassland and starts rising to the left. Watch out for a stile down on the right, into woodland. Across this, turn left on a small path that emerges near the Wimbleball Dam. A side-trip on to the dam gives fine views of Hartford Bottom below.
3 Return along the dam and turn right into a descending tarmac lane signed 'Bury 2½'. At the bottom keep ahead on a concrete path signed 'Bridleway'. With a bridge ahead, bear left on to a grass track, this time signposted 'Bridleway to Bury'. It leads to a ford, so watch out for the footbridge on the right. Once across, take a track between houses, to turn left out into Hartford.
4 Turn left ('Bury 2') on a well-used track, partly tarred, partly mud. It passes through woods of oak and beech beside the River Haddeo. The track is now stony to the little village of Bury.
5 Turn left to the packhorse bridge beside the road's ford. Ignore a riverside track on the left and continue for 180yds (165m) to turn left at a bridleway sign. Here pass between houses to a sign for Haddon Hill, and a sunken track. This climbs steeply, with a stream in its bottom that flows over orange bedrock. At the top it continues as a green (or brown) track between grown-out hedges, before turning left for another short climb to Haddon Farm.
6 Pass to the left of the farm's buildings, on to its access track. After ¼ mile (400m) this reaches the corner of a wood. After another 70yds (64m) a stile above leads into the wood. Ignore the pointing signpost but bear left to go up the left-hand side of the wood to a gate on to the open hill. Go up alongside the wood to its top corner.
7 Take a track that bears left to cross the crest of the hill. Here turn sharp right, on a wide track that runs to the top of Haddon Hill. Continue downhill, through thin, peaty soil that grows only some sparse grasses, to the car park.
You'll probably find it hard to imagine an outward force of 3.3 tons per square foot (36 tonnes per square metre) but that is the force exerted by the waters of Wimbleball Lake against the wall which contains them.
Some 200,000 tons of crushed stone from a quarry at Bampton was used to construct the dam in the mid-1970s. Sand from Cullompton was chosen to impart a pinkish colour and match the local bedrock. It's made of concrete, though the surface texture vaguely imitates massive stonework; and the 13 buttresses have no particular structural purpose but, aesthetically, they prevent it from looking too huge. The dam took four years to build, and the reservoir behind it needed another year just to fill up.
The reservoir holds almost 5 billion gallons (23 billion litres), which is enough to supply the whole South West peninsula for 44 days, or a town like Bridgwater for 9½ years. Its main job is to store water from the winter through into summer. It is also used to maintain the water level in the River Exe. When the river is full, a pipeline pumps water from Exebridge near Dulverton up into the reservoir. For the rest of the time the same pipeline, working the other way, delivers water to Dulverton. And, when it's really dry, the reservoir releases water into the Haddeo below the dam and so back into the Exe. Some of this will be water that had already flowed down the Exe during the previous winter.
Some 50 years ago water boards took the view that humans were dirty beasts who shouldn't be allowed anywhere near their own drinking water. However, Wimbleball was planned from the start to provide not only drinking water but also recreation: fishing water, sailing water and walk-around-it water. (If you've half a day to spare, you can do a complete circuit on a waymarked path.) The woodland that looks so natural was planned by landscape architect Dame Sylvia Crowe and planted just 30 years ago, with the trees around the car park being the first to go in. Sadly, nothing can be done about the ugly and barren foreshore, since no plant can establish itself on ground that is submerged for months at a time. But, thanks to careful management, the weird, rattling cry of the nightjar now floats across the drinking water.
To finish with, here are some more numbers to ponder as you are walking: 1½ million people live downstream from Wimbleball Lake and drink its water, but every year 2 million sail on it, fish from it, or just walk down to its shores to have a look.
Dulverton, the so-called capital of Exmoor, remains an attractive small town. It has a very good selection of cafés and pubs, and the Exmoor Information Centre in Fore Street is a useful entry point for the National Park.
Lowtrow Cross Inn is on the B3190, 2 miles (3.2km) east of Wheddon Hill car park. It's an old drover's halt, and in a sense carries on the trade, though travellers now park caravans, not cows, in the field alongside. There is a summer tea shop at Cowlings on the west side of the reservoir.
Haddon Hill is the largest area of heathland in the Brendons. In June or July you may see the heath fritillary. This is a fairly small butterfly, coloured brown and reddish-orange; within the UK it flies only in a few scattered spots in the far south.