Lake Memphremagog (; , ) is a freshwater glacial lake located between Newport, Vermont, United States and Magog, Quebec, Canada. The lake spans both Quebec and Vermont, but is mostly in Quebec. Most of the watershed that feeds the lake is located in Vermont, and is a source for accumulated phosphorus, sediments, and other pollutants. Cleanup efforts since the late 1980s have improved the water quality. The lake furnishes potable water for 200,000 people.
Physical characteristics The lake is long with 73 percent of the lake's surface area in Quebec, where it drains into the Magog River. However, three-quarters of its watershed, , is in Vermont. The total is , with located in Quebec. In Vermont, the lake lies in parts of the towns of Derby and Newport, in addition to the City of Newport, all in Orleans County. In Quebec, the lake lies in parts of Austin, Magog, Ogden, Potton, Saint-Benoît-du-Lac, and Stanstead Township, all in Memphrémagog Regional County Municipality. The lake occupies most of what the Vermont Agency of Natural Resources calls "Basin 17". At the very south end of the lake, there is the South Bay, connected by the narrowest part of the lake.
The lake elevation is approximately above mean sea level. The lake level is set in the treaty signed in 1935 between the United States and Canada and is controlled by the dam on the Magog River at the northern end of the lake. Both ends of the lake are fairly shallow, with depth ranges of to . The lake bottom takes a dramatic drop in Canada, starting opposite Mont Owl's Head and continuing that way north to Gibraltar Point, where it starts to climb back to the shallows of the north end. Its maximum recorded depth of is located in Canada, opposite Jewett Point (at approximately ). The lake is the third deepest in Vermont.Behind Lake Champlain at deep and Lake Willoughby at deep It contains 21 islands. Province Island, the largest, is divided by the international border. The lake is irregular in shape, and along its shores are several striking indentations, in some places low, and in some other parts high and rocky. Along the western shore of the lake are several mountains, prominent among which are Owl's Head, Elephantis, and the Hog's Back.
Islands
There are 21 islands on Lake Memphremagog. Of these, five are in the United States, one is international, and 15 are in Canada. Many of the islands have had several names throughout history; the current names are provided.
Islands in the United States
Horseneck Island (at approximately ) is the southernmost island on the lake and is near the eastern shore. Bell Island (at approximately ) is one of the Twin Sister islands (the other being Black Island) and is south of Gull Rocks and Black Island. Gull Rocks (at approximately ) is north of Bell Island and south of Black Island. Black Island (at approximately ) is one of the Twin Sister islands (the other being Bell Island) and is north of Gull Rocks and Bell Island. Cove Island (at approximately ) is east of Black Island.
International Islands
Province Island (at approximately ) is crossed by the international boundary. About one tenth of the southern end of the island is in the United States; the remainder is in Canada.
Islands in Canada
Tea Table Island (at approximately ) is north-northeast of Province Island, west of Reid Bay, and south of the Cedarville Wharf. Round Island (at approximately ) is near the western shore of the lake. Whetstone Island (at approximately ) is on the eastern shore at the entrance to Fitch Bay and is south of Gull Island. It is named for the novaculite oil stone (sold as "Magog Oil Stone") that was mined there.Abbott, Louise. Memphremagog: An Illustrated History, Vol. 1, Georgeville Press, Georgeville, Quebec 2017. Gull Island (at approximately ) is north of Whetstone Island and at the entrance to Fitch Bay. Loon Island (at approximately ) is in Fitch Bay. Minnow Island (at approximately ) is east of Skinner's island. The island is primarily composed of granite.Abbott, Louise. Memphremagog: An Illustrated History, Vol. 2, Georgeville Press, Georgeville, Quebec 2017. Skinner's Island (at approximately ) is west of Minnow Island and south of Long Island.The island is primarily composed of granite. Long Island (at approximately ) is north of Skinner's Island. Molson's Island (at approximately ) is on the eastern shore. Lord's Island (at approximately ). Eagle Island (at approximately ) is north of Hermitage Point and west of Hermitage Bay. Three Sisters (at approximately , , and ) are three small islands that are grouped together. Charest Island (at approximately ) is the northernmost island on the lake and is in Magog, Quebec.
Hydrology
Four Vermont rivers directly empty into the lake: the Clyde, Barton, the Black and the Johns River.
In the middle of the winter, the ice on the lake can become thick.
The Magog River, in Quebec, drains the lake towards the northeast. The hydroelectric-producing Memphemagog Dam, on the Magog River, regulates the water level of the lake. Its level is governed by a treaty signed in 1935 between the United States and Canada.
Geology During the ice age, the lake was a proglacial lake which covered Lake Magog, Lake Brompton, and much of the Saint François watershed including East Angus, Sherbrooke, and Windsor.
Ecology Like many other lakes, Memphremagog is accumulating phosphorus, sediments, and other pollutants, primarily runoff from farms, but from other sources as well. Exotic species infestations are a concern, with an existing Eurasian water milfoil population and the potential for a zebra mussel infestation. Since the 1970s, significant efforts have been made to reduce the polluting effects of direct discharges into the lake and its tributaries, and lake quality has improved.
In 1994, the Lake Memphremagog Watershed Association was formed to focus on solving lake and river issues. Testing done in 2008 was unable to determine the cause of excessive nitrogen and phosphorus.The Chronicle, July 1, 2009, page 2A, "Search continues for sources of pollution," Richard Creaser In 2010, a study revealed that farms contribute disproportionately to nutrient loads. Although farms have 16% of total land use in the drainage area, they produce 44% of the runoff. Baseline nutrients for a lake are 14 micrograms of phosphorus per litre of water. The lake was measured at 17 micrograms, 18% above the standard. Although the acreage devoted to farming has decreased, the retired land has most often been developed, itself a source of runoff.
In 2026, a clonally transmissible melanoma was identified among brown bullhead catfish in the lake.
Origin of name The lake is within the larger territory originally inhabited by the Abenaki tribe. The lake's name, Memphremagog, is derived from the Algonkian language: Memphremagog comes from the word Memrahabegek, which means "where there is a big expanse of water". Memphremagog was also pronounced as "Mamphremagog". This came from the Abenakis' Mamlawbagak which signifies "a long and large sheet of water". The prefix mamlaw denotes largeness or abundance; the particule baga denotes water; and "k" marks the name as given in local term.
History
In 1753, the Abenakis brought the ransomed John Stark down the lake and came ashore where Newport is now.
Rogers' Rangers were forced to retreat south following their attack on Saint-Francis, Quebec in 1759. To confound their avenging pursuers, they split up on the east shore of the lake.
The first accurate depiction of the map was in 1776. This marks the beginning of interest by settlers.
In November 1927, a major flood occurred representing the largest ever in northern Vermont. Although the amount of storage provided by the numerous lakes and ponds in both basins reduces the potential of floods.
In June 1942, a single-engined Royal Canadian Air Force training plane crashed into the lake near the west shore near Newport, killing the pilot, Roy N. Pate, its only occupant.
In 2010, the U.S. Fish and Wildlife Service accepted a bequest of of undeveloped land on the shores the lake on Eagle Point along the border with Canada.
In September 2020, a leak at the sewage treatment facility in Newport, Vermont dumped about 7,000 gallons of effluent into the lake.
Steamships
The Mountain Maid paddlewheeler operated from 1850 to 1870. Officially launched on June 27, 1850, it had a wooden hull that was about to long and in breadth. It was originally named the Rhoda Ann and renamed to the Mountain Maid in 1851. The captain was George W. Fogg. It carried passengers and cargo, operating from Newport to Magog with six stops in between. The ship was scrapped in 1892.
The Lady of the Lake was an iron hulled steam excursion/ferry sidewheeler. It was launched in late September, 1867. The ship made the trip from Newport to Magog in 3 hours, including stops. Usually, it made two trips daily. It was retired in 1915 and stopped operations in 1917. It was based in Newport.
The Anthemis steamer was built in 1909 to carry 300 people. It was in operation until 1953.
The steamer Minnie operated in the 1870s. The Memphremagog (later renamed the Magog) operated in the 1880s; it was larger than the Mountain Maid. Other smaller steamers offered ferry, freight and cargo, and towing services on the lake.
Memphre Lake Memphremagog allegedly contains a cryptid named Memphre (or Memphré), which has received sightings since the 18th century and continues on in the folklore of the area. A sighting of Memphre was reported in 2000.
Lighthouses Lake Memphremagog is known to have had at least three lighthouses on the Vermont side and seven on the Quebec side. These were used in aiding boaters in navigating the waters of the large lake.
Vermont lighthouses All three of the original lighthouses have been demolished.
Maxfield Point Light
The Maxfield Point Light was a small lighthouse constructed on the Vermont side of Lake Memphremagog in 1879. A conical, cast iron structure, it was 25 feet (7.6 m) tall, with a focal plane 40 feet (12.2 m) above sea level. It showed a fixed white light, visible for 10 (16 km) miles. The lighthouse no longer exists; it is unknown what happened to it, or when it was deactivated.
Newport Wharf Light The Newport Wharf Light was a tower that was built in the Newport section of Lake Memphremagog in 1879. The lighthouse was a steel skeleton tower, painted red, that was fixed on a concrete foundation. The tower showed a fixed red light that was visible for up to , with the height of the focal plane being 37 feet (11.2 m). As with the Maxfield Point Lighthouse, the date this lighthouse was demolished is unknown.
Whipple Point Light Whipple Point Light was a tower that was built on the end of a pier on Whipple Point in Lake Memphremagog. Built in 1879, the tower was constructed of wood in a hexagonal shape and stood 13 feet (4 m). The light was fixed white and was visible from up to away, with a focal plane of 25 feet (7.6 m). The lighthouse was deactivated around 1906 and was demolished at an unknown date.
Quebec lighthouses Most of the Quebec lighthouses were originally established in 1878. None of the original lighthouses have survived, although some of them have been replaced by simple navigation lights. From north to south, the lighthouses were:
Magog Lighthouse
Magog Lighthouse was located on a freight shed and had a fixed red light with a range of . It was built in 1910 and located near Magog. It was demolished on an unknown date.
Witch Shoal Lighthouse