Lake Vyrnwy, Wales, United Kingdom

Lake Locations:

United Kingdom - Wales - Mid Wales -

Also known as:  Llyn Efyrnwy, Vyrnwy Reservoir

Lake Vyrnwy (Llyn Efyrnwy in Welsh) is a beautiful man-made reservoir constructed in 1888 to provide the City of Liverpool with a reliable and plentiful source of fresh water. Just south of Snowdonia in the county of Powys in Mid Wales, the 1,122-acre (4.54 square kilometer) lake is today managed by Severn Trent Water and the Royal Society for the Protection of Birds. The lake still provides sparkling clean water for the residents of Liverpool, along with many opportunities for recreation and exploration of the magnificent Welsh countryside.

Although the second largest reservoir in Wales, Lake Vyrnwy is a rather secluded body of water. Only a few towns sit along the nearly 12 miles of pristine shoreline, making the area a paradise for visitors who enjoy the peace and tranquility of nature. Activities on and around the lake are numerous with fishing, sailing, canoeing, rock climbing, cycling and horseback riding opportunities in abundance. A relatively flat cycling trail circles the entire lake and offers an incredible view of the mountains and dense forests in the area.

The most distinct feature of Lake Vyrnwy (pronounced Vernwee) is the dam. Started in 1881 and completed in 1888, the large stone-built dam was the first of its kind in the United Kingdom. Earlier dams in Britain had been built by creating large earth embankments to hold back water on streams and rivers. Unchanged from the day it was built, the dam measures 140 feet (44 meters) high from the bottom of the valley and 130 feet (39 meters) thick at the base. The length is 1,170 feet (357 meters) and accommodates a narrow road bridge along the top. The dam is ornately decorated with over 25 arches and two towers (each with four corner turrets) that rise 13 feet (four meters) above the road surface. The Vyrnwy dam was the first dam to allow water over its crest instead of in a channel along the side. At the bottom of the dam is a body of water known as the Stilling Basin which absorbs the energy from the water that flows over the crest and into the valley. The basin prevents the force of the falling water from eroding the foundation of the dam.

When the Vyrnwy Reservoir was still in the planning stages, one of the biggest problems encountered was the valley village of Llanwddyn which would be flooded as the reservoir filled. Llanwddyn consisted of a church, two chapels, three public houses, 37 houses and 10 farmsteads. The entire village had to be relocated and rebuilt farther downstream before the first stone of the dam could be laid. Today, the village of Llanwddyn has a population of 300 and has several cafes and gift shops. The town is a popular tourist stop due to its location near the border of Snowdonia National Park, and the Cambrian and Berwyn Mountains. During drought conditions, when the water level of the reservoir can be low, the old foundations of several original Llanwddyn buildings can be seen.

The West and East Towers on the Lake Vyrnwy dam release compensation water through huge valves to maintain the River Vyrnwy (or Afon Efyrnwy in Welsh), which was totally impounded by the building of the dam. The river was originally fed by the streams and waterfalls which now empty into Lake Vyrnwy. Beginning at the foot of the dam, the river flows for 39.7 miles (63.9 kilometers) east towards Britain, where it eventually converges with the River Severn near the village of Melverley on the Welsh border. Depending on the water levels downstream, the towers may release up to 10 million gallons (45 megaliters) of water into the river each day. Inside the West Tower is a an electrical generator which is driven by water leaving the reservoir. Before modern power lines arrived in the 1960s, the generator was Llanwddyn’s only source of electricity.

Just before the Lake Vyrnwy dam is the reservoir’s straining tower. The purpose of the tower is to filter out material in the water through a fine metal mesh, before the water flows along a 68 mile (109 kilometer) aqueduct into Liverpool. Constructed at the same time the dam was being built, the picturesque, gothic tower stands 210 feet tall (63 meters) of which 49 feet (15 meters) is below water, and is topped with a pointed copper clad roof. Second to the dam, the tower is one of the most photographed landmarks in the area.

In addition to being a reservoir, Lake Vyrnwy is also a National Nature Reserve. In 1977, the Royal Society for the Protection of Birds (RSPB) was given joint management of 16,000 acres of Lake Vyrnwy. The RSPB has several bird hides around the lake, where rare species are known to breed such as the peregrine falcon, the pied flycatcher, and the wood warbler. Around 90 species of birds have been recorded to be living on the reserve. The reserve also has the largest remaining tract of heather moorland in Wales which is home to a number of birds rarely found in other parts of the country.

Shortly after completion of the dam, Lake Vyrnwy was stocked with 400,000 Loch Leven trout. Today anglers will find the lake full of wild brown trout, stocked brown trout and rainbow trout. There are several boat launches around the lake and many places to rent a boat. Fly fishing is the preferred method of fishing with just as many anglers along the shoreline as in the water.

A total of 31 streams, waterfalls, and rivers flow into Lake Vyrnwy. On the northern edge of the lake sits the hamlet of Rhiwargor where the rivers Afon Eiddew and Afon Naedroedd meet. Up the hill from Rhiwargor, the Rhiwargor Waterfall, the largest in the area, flows down the heather-clad slopes of the valley of Afon Eiddew and into the lake. A two mile trail leads to the base of the waterfall and is a great spot to cool off and have a picnic.

Accommodations on Lake Vyrnwy consist of holiday cottages, bed and breakfasts, a few hotels, and camping and caravan parks. Many self-catering cottages are located on beautiful farms and offer trails, private beaches, and a great base site for cycling, hiking, and bird watching. The 12-mile trail around the lake is popular with cyclists and walkers. For those who did not bring a bike, bike rentals are available including tandem bikes. Additional vacation rentals and real estate can be found near Snowdonia and the Snowdonia National Park, just west of the lake. As well as being the largest National Park in Wales, Snowdonia boasts the highest mountain in Wales, and the largest natural lake in Wales, as well as a number of small, picturesque villages.

A must-see on a visit to Lake Vyrnwy is the Llanwddyn Sculpture Trail in the valley below the dam. Started in 1995 the trail features over 50 wooden sculptures, created by master sculptors from across the world, placed at picnic sites and clearings around the lake.

Set against the backdrop of the majestic Berwyn Mountains, no stay in northern Wales is complete without a visit to Lake Vyrnwy. Whether you enjoy culture or the great outdoors, the tranquil shores of this crystal-clear lake offer fantastic holiday accommodations and a chance to explore a relatively untouched and fascinating area.

Things to do at Lake Vyrnwy

  • Vacation Rentals
  • Fishing
  • Boating
  • Sailing
  • Swimming
  • Beach
  • Canoeing
  • Camping
  • Picnicking
  • Hiking
  • Rock Climbing
  • Biking
  • Horseback Riding
  • Waterfall
  • Birding
  • National Park

Fish species found at Lake Vyrnwy

  • Brown Trout
  • Rainbow Trout
  • Trout

Lake Vyrnwy Photo Gallery

Lake Vyrnwy Statistics & Helpful Links

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Lake Type: Artificial Reservoir, Dammed

Water Level Control: Severn Trent Water

Surface Area: 1,120 acres

Shoreline Length: 12 miles

Normal Elevation (Full Pond): 825 feet

Maximum Depth: 84 feet

Water Volume: 48,372 acre-feet

Completion Year: 1888

Drainage Area: 36 sq. miles

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Trophic State | LakeLubbers

Trophic State measures the level of algae and nutrients in a lake.

An oligotrophic lake is very clear (blue in color) and does not support much plant or fish life. A hyper-oligotrophic lake is the clearest of all lakes, and is nearly devoid of plants and fish.

A mesotrophic lake is slightly green and supports a moderate degree of plant and fish life. A lake's most desired trophic state is generally this mid-point - the mesotrophic state.

A eutrophic lake is somewhat murky and supports a large amount of plant and fish life. A hypereutrophic lake is clouded with algae, plant life, and fish life. A eutrophic or hyper-eutrophic lake can be difficult to navigate by boat - and is often an unpleasant place to swim.

The use of phosphorus-rich and nitrogen-rich fertilizer on lawns and golf courses surrounding a lake can cause it to become eutrophic or hypereutrophic.


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Catchment or Drainage Area | LakeLubbers

This is the surrounding area that drains into a lake, including land, rivers and their tributaries. This is also known as the lake's "catchment basin".

Small lakes at the highest peaks of mountains have small drainage areas. The world's oceans have the largest drainage areas.


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Lake-Area Population | LakeLubbers

This is the estimated number of people who live in a house with a view of a lake, plus those who self-describe the lake as their home, for example: "I live at Smith Mountain Lake."


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Water Residence Time | LakeLubbers

This is the estimated time that it takes for an amount of water equal to the entire volume of a lake to flow out of - or evaporate from - the lake.

Residence Time can be as short as a few days for fast-flowing small lakes, and can exceed 100 years for slow-flowing large lakes.


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Completion Year | LakeLubbers

This is the year that a reservoir was first filled to the reservoir's normal elevation - or the year that a natural lake was first dammed. A large reservoir can take more than a year to fill after its dam is first closed.

The Grand Anicut in southern India is generally considered the world's oldest dam that still operates. Grand Anicut was constructed in the second century BC. It now impounds an irrigation network that includes roughly one million acres.

You can find many of the the world's newest reservoirs on LakeLubbers. Many of the world's oldest reservoirs appear on the last page of that list.


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Water Volume | LakeLubbers

This is the estimated volume of water that a lake contains -- measured at the lake's normal elevation. By this measure, the world's largest freshwater lake is Siberia's Lake Baikal.

You can find many of the the world's largest lakes (by water volume) on LakeLubbers.

Water Volume can be measured in acre-feet, in cubic miles, or in cubic kilometers. One acre-foot is the amount of water needed to cover one acre (43,560 square feet) to a depth of one foot. One cubic mile equals 3,379,200 acre-feet. One cubic kilometer equals 810,713 acre-feet.

1 acre-foot is equal to 325,851 US gallons. Siberia's Lake Baikal contains about 6,276,367,740,000,000 gallons of freshwater - nearly 1 million gallons for every living person on earth.

The other - and more widely used - measure of a lake's size is the lake's surface acreage. By that measure, the world's largest freshwater lake is North America's Lake Superior.


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Maximum Depth | LakeLubbers

This is the estimated greatest depth of the water in a lake -- measured at the lake's normal elevation. The world's deepest lake is Siberia's Lake Baikal; that lake's maximum depth is estimated at 5,314 feet.

You can find many of the the world's deepest lakes on LakeLubbers. If you select the last page of that list, you will find the (maximum depth of) the shallowest lakes in our database.


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Average Depth | LakeLubbers

This is the estimated average depth of the water in a lake -- measured at the lake's normal elevation. If the water volume and surface area of a lake are known, an estimate of the lake's average depth can be calculated:

Water volume ÷ Surface Area = Average Depth

Example: 1,000,000 acre-feet ÷ 20,000 acres = 50 feet average depth


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Maximum Elevation | LakeLubbers

This is a lake's highest water level, measured by the lake's surface distance above sea level, that can occur during flooding. A lake's highest possible maximum elevation is usually the top of the lake's dam or spillway.

At lakes that include residential development, government regulations usually forbid the construction of homes below a lake's maximum elevation.


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Minimum Elevation | LakeLubbers

This is a lake's lowest water level, measured by the lake's surface distance above sea level, that can be reasonably expected to occur. Low lake levels can occur due to deliberate seasonal draw downs for irrigation or impending snow melt, reduced water inflows, drought and evaporation, residential or commercial water demands, and hydropower generation.

Some lakes' minimum and maximum elevations are virtually the same. Lakes that generate hydropower may vary by several feet - according to power demand. Lakes whose primary purpose is to prevent flooding can seasonally vary by 100 feet or more.

When some lakes reach their minimum elevation, their boat ramps may not be long enough to permit boat access - and boats docked on shallow parts of the lake may end up on dry ground. In those cases, kayakers and shore-based anglers may be among the few happy recreational users of the lake.


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Normal Elevation | LakeLubbers

This is a lake's normal water level, measured by the lake's surface distance above sea level. For a reservoir, this water level is also known as "full pond" or "full pool".

You can find many of the world's highest-elevated lakes on LakeLubbers. Lakes with the lowest elevations (known by LakeLubbers) are shown on the final page of that list.


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Shoreline Length | LakeLubbers

This is the length of the exterior shoreline around a lake - measured at the lake's normal elevation. The shoreline length can be considerably shorter or longer when lake water levels are lower or higher than normal.

A lake with many coves has a much longer shoreline than a lake of similar surface area that is nearly circular in shape.

When known, the shoreline miles that we report in our statistics include only the lake's exterior shoreline, and exclude the shorelines of islands located within a lake's boundaries. In lakes with many islands, those islands' combined shorelines may exceed a lake's exterior shoreline.

You can find many of the world's longest-shoreline lakes on Lakelubbers.


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Surface Area | LakeLubbers

This is the area (acreage, square kilometers, etc.) of the top surface area of a lake - measured at a lake's normal elevation. The surface area can be considerably smaller or larger when lake levels are lower or higher than normal. North America's Lake Superior is the world's largest freshwater lake by this measure.

The other measure of a lake's size is the lake's water volume. By that measure, the world's largest freshwater lake is Lake Baikal in Siberia.

You can find many of the world's largest lakes (acres) on Lakelubbers. There is no widely-accepted minimum surface area that defines a lake. What Lakelubbers describes as a lake, you might call a pond. The smallest lake that Lakelubbers currently includes is Hawaii's 2-acre Lake Waiau.


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Water Level Control | LakeLubbers

This is the organization that controls water releases or outflows from the lake or reservoir. In the USA, this is often the US Army Corps of Engineers, a power company, a municipal water system, an irrigation district, or a paper manufacturing company. In the case of private or gated lakes, a homeowners' association may be the lake's controlling authority.

Many lakes cross borders, including North America's Great Lakes. The control of such lakes and their coveted freshwater may be amicably shared - or hotly disputed.

"Water wars" continue at many lakes as growing populations and crop irrigation needs compete for the freshwater that lakes contain.


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Lake Type | LakeLubbers

There are 3 basic types of lakes that are currently included on LakeLubbers. 2 types may be dammed or not dammed, producing 5 classifications.

- A Reservoir is a man-made freshwater lake that is usually created by damming rivers.

- A Natural Freshwater Lake occurs naturally - often by glacial activity - and has a salinity of less than 30 parts per thousand. It may be dammed to produce electricity or for other reasons.

- A Natural Saltwater Lake occurs naturally and has a salinity of more than 30 parts per thousand (ppt). It may be dammed.

"Brackish" water may be categorized as freshwater or saltwater, depending on its salt content (salinity). Oligohaline water has less than 15 ppt of salt. Mesohaline water has 15-29 ppt. Polyhaline has 30-335 ppt.


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