Kentmere Reservoir facts for kids

Quick facts for kids Kentmere Reservoir
Looking down on the reservoir from Froswick
Kentmere Reservoir Location in Lake District
Location	Kentmere, Cumbria
Coordinates	54°27′54″N 2°51′27″W / 54.46500°N 2.85750°W / 54.46500; -2.85750
Type	reservoir
Catchment area	1,330 acres (5.4 km2)
Basin countries	United Kingdom
Surface area	38.5 acres (15.6 ha)
Water volume	35.4 million cubic feet (1,000 Ml)

Kentmere Reservoir is a large lake built by people in the Kentmere valley in Cumbria, England. It's about 10.5 kilometres (6.5 mi) north-northeast of the town of Windermere. The reservoir gets its water from streams that form the start of the River Kent. These streams begin about 1.5 kilometres (0.93 mi) north, in an area called Hall Cove, on the slopes of a mountain ridge named High Street. It also gets water from Lingmell Gill, which flows from a large bowl-shaped valley on the side of Harter Fell, near the Nan Bield Pass.

In the 1840s, a natural lake called Kentmere Tarn was drained to create more farmland. This caused problems for the mills further down the river, as their water supply became uneven. To fix this, the mill owners decided to build a reservoir to control the river's flow. They hired an engineer named John Frederick Bateman to help them. An official law, called an Act of Parliament, was passed in 1845, allowing five reservoirs to be built. Even though Bateman thought another location, Skeggles Water, would be better, the mill owners chose to build the reservoir at Kentmere Head. It was finished in 1848, but it cost much more than they expected.

Mill owners used to pay for the water based on how much the river level dropped at their mill. Smaller mills didn't have to pay. Soon after the reservoir was built, cheap coal became available thanks to new railways. This meant mills started using steam power instead of water power. This change sped up even more after a law in 1963, which made it very expensive to use river water for power.

By 1972, most mills had stopped using water power. A company called James Cropper, which owned paper mills at Burneside, became the owner of the reservoir. They were the last company to use its water. By 1995, the dam had serious problems. There was even talk of breaking the dam so it wouldn't need expensive safety checks. However, people were very upset because the reservoir is in a beautiful natural area. So, even though Croppers didn't need the water anymore, they paid for repairs. This meant the maximum water level was a little lower, and a wall was built on top of the dam to protect it from waves.

Building the Reservoir

Before the 1800s, most of the land around Kentmere was open land shared by everyone. But then, wealthy people started buying farms and fencing off the land. They used lime from a quarry to improve the soil and added drains to make the land better for farming. In the 1830s, the Wilsons, who owned Kentmere Hall, drained Kentmere Tarn, hoping to create good farmland. However, these changes caused unexpected problems for the mill owners downstream. The natural bogs that used to release water slowly into the river were gone. This meant the river's flow became very uneven, stopping the mills from working properly.

Building a reservoir was part of a bigger plan to create several reservoirs in the Kendal area. These reservoirs would help control the flow of the River Sprint, the River Mint, and the River Kent. By 1844, there were many mills on these rivers, making things like wool, gunpowder, paper, and iron. Water power was very important because there was no coal nearby. Ten mill owners and the mayor of Kendal formed a group to build reservoirs to keep the rivers flowing steadily.

The group quickly hired the famous water engineer John Frederick Bateman to advise them. He had someone survey the possible reservoir sites in late 1844. Soon, there was a big debate in the local newspapers about the plan. People against it worried about the high cost, that it would only help a few mill owners, and that it would use up valuable farmland. They also feared what would happen if a dam broke. Supporters argued that Kendal was falling behind other towns that had cheap coal. They believed that helping the mills work regularly would boost local manufacturing and make the town more successful.

The group of mill owners and the mayor considered Bateman's report. They then asked the government for permission to build the reservoirs in 1845.

Plans for the Reservoirs

The plan became an official law when Queen Victoria signed it on July 21, 1845. This law allowed the building of Kentmere Head reservoir. It was designed to hold 44 million cubic feet (1,200 Ml) of water, with an earth dam 57 feet (17 m) high. It would collect water from a large area of 1,330 acres (540 ha). Even though this area was relatively small, the rainfall there was very high. The area also had plenty of rock and clay for building.

The law also allowed for four other reservoirs:

• Skeggles Water: This reservoir would have had a 26-foot (7.9 m) high dam and held 85 million cubic feet (2,400 Ml) of water. It would have been the largest of the planned reservoirs in terms of surface area. Bateman preferred this one, thinking it would be the cheapest and provide a lot of water.
• Bannisdale (Lower and Upper): Bateman suggested two reservoirs here because building one very tall dam (130 feet (40 m)) was too difficult at the time. The lower dam would be 64 feet (20 m) high, and the upper dam 60 feet (18 m) high.
• Longsleddale: This reservoir would have had a 74-foot (23 m) high dam and held 67 million cubic feet (1,900 Ml) of water. It would have flooded most of the upper valley.

The law named 12 people, called Commissioners, to oversee the project. They all had to own mills on the affected rivers. The Commissioners could choose to build any or all of the five reservoirs. They could also borrow money for construction and charge mills for using the water. The charges were based on how much the river level dropped at each mill. Some small mills were exempt from these charges. The law also stated that only these Commissioners could build reservoirs in these valleys.

Building Kentmere Reservoir

Even though Bateman thought Skeggles Water was the best choice, the Commissioners decided to build Kentmere Head reservoir first. On October 9, 1845, they hired a company called Shuttleworth and Dobson to build the dam. The cost was £6,150, and they also paid £960 for the land. A small house for the reservoir keeper cost £45. These costs were much higher than Bateman's original estimate. By the time the work was finished in the summer of 1848, the total cost was £13,435. Soon after, a flood damaged the overflow channel, and it cost another £686 to repair and extend it.

While Bateman wasn't directly involved in the building, his detailed instructions for the dam were kept. They said that the clay core of the dam should be built in layers, each about 8 inches (20 cm) thick. The clay had to be soaked for 12 hours, then cut into blocks and pressed into the layer below. The earth dam itself was to be built with curved layers, 2 feet (0.61 m) thick on the upstream side (the side facing the water) and twice as thick on the downstream side. The upstream side needed to be made of sticky, waterproof material, while the downstream side could be made of drier, stony material. The dam was sloped, and its central clay core was 10 feet (3.0 m) thick at the top and 12 feet (3.7 m) thick at the bottom. The upstream side was covered with stone, and a pipe for water to flow out ran through the bottom of the dam.

Out of the five planned reservoirs, only Kentmere Head was built. By the time it was finished, railways had reached Kendal, bringing cheap coal from other areas. Mills started using steam engines instead of water power. Because of this, there was no longer much interest in building more reservoirs or paying for water. So, the group of Commissioners for all the Kendal reservoirs became just the Commissioners for the Kentmere Reservoir.

How the Reservoir Was Used

Over time, fewer and fewer mills used water power. James Cropper & Company became the biggest user when they opened a paper mill in 1880. As other large mills closed or switched to steam, Croppers became the only company paying for the reservoir's upkeep. They have paid for its maintenance ever since.

A law passed in 1930 required reservoirs to be inspected for safety. In 1933, an engineer reported that the Kentmere dam had some sinking, leaks in its clay core, and at least one broken outlet pipe. Repairs were made, and all the outlet pipes were replaced. A new valve was installed on the upstream side of the dam, with controls running up to the top.

One problem that came up later was that the old water channel inside the dam wasn't designed to handle pressure from the new valve. In 1964, the entrance to this channel collapsed. Workers fixed it by welding oil drums together to form a tube and then filling the gaps around it with concrete. As the steel drums rusted away, it became clear that some gaps hadn't been filled, so more concrete was added in 1977. Also, over 120 years, the clay core of the dam had settled, meaning water could soak through the material above it. To prevent problems, a new overflow channel was cut, which lowered the maximum water level by 3.5 feet (1.1 m). This reduced the amount of water the reservoir could hold.

By 1970, only five mills were still working on the River Kent. A new law in 1963 allowed authorities to charge mills for every thousand gallons of water they used to generate power, even if the water was returned to the river. This made using water power too expensive. Croppers, who used water to power turbines for electricity, had to shut down their turbines in 1972.

Since then, Croppers has tried to give away the reservoir. In 1995, after no one wanted to take it, they offered to give it to anyone for free if they would pay for £100,000 in repairs and over £2,000 in yearly maintenance. No one came forward, and Croppers remains the owner.

In 1995, an engineer noticed a lot of water leaking from the reservoir. Croppers agreed to have an inspection done early. This inspection involved draining the reservoir and using cameras to look inside the pipes. They found serious problems with a channel through the dam. The inspector would not allow the reservoir to be refilled until repairs were made. Options included breaking the dam, greatly reducing the water level (so it wouldn't need strict safety laws), or doing immediate repairs.

Because the reservoir is in the beautiful Lake District National Park, people were very upset at the idea of breaking the dam. Reducing its capacity was also unpopular. So, even though Croppers didn't use the water, they decided to pay for the repairs. The work included strengthening the dam's base and top, putting a new pipe inside an old one, building a wall along the top of the dam to stop waves from causing damage, and cleaning out a tunnel. The work cost £100,125 and started in August 1996. After all the repairs, the reservoir was slowly refilled. The work made the reservoir safe and strong, and it is expected to last for many decades. The local community thanked James Cropper for the repairs.

Where to Find Kentmere Reservoir

The reservoir is built in an area with strong, slate-like rocks that don't let water through easily. The dam wall is 832 feet (254 m) long at its top. It has a stepped overflow area at the western end, and a lower outlet for the River Kent in the middle of the dam. The reservoir is in a quiet, hidden spot, surrounded by mountains called Yoke, Froswick, Ill Bell, Thornthwaite Crag, Harter Fell, Mardale Ill Bell, and Kentmere Pike. These mountains form a horseshoe shape around the valley, with steep slopes leading down to the water, offering amazing views of the reservoir.