Question: Torteval, Guernsey contains a bird reservoir that was redeveloped to mark what anniversary?

Context articles: George Métivier
Pleinmont-Torteval
Diamond Jubilee of Queen Elizabeth II
Saint Peter, Guernsey
Guernsey Dam
Framingham Reservoir No. 1 Dam and Gatehouse
Guernsey State Park
Lower Peirce Reservoir
Torteval, Guernsey
Prettyboy Reservoir

George Métivier (29 January 1790 – 23 March 1881) was a Guernsey poet dubbed the "Guernsey Burns", and sometimes considered the island's national poet.
 He wrote in Guernésiais, which is the indigenous language of the island.
 Among his poetical works are "Rimes Guernesiaises" published in 1831.
 Métivier blended together local place-names, bird and animal names, traditional sayings and orally transmitted fragments of medieval poetry to create themes.
Pleinmont-Torteval is an area in Guernsey.
 It is part of the parish of Torteval, which is split into two, by St. Pierre du Bois.
 The other part is often called just "Torteval" to distinguish it from "Pleinmont-Torteval".
The Diamond Jubilee of Queen Elizabeth II was a multinational celebration throughout 2012, that marked the 60th anniversary of the accession of Queen Elizabeth II on 6 February 1952.
 Queen Elizabeth is queen regnant of 16 sovereign states, known as Commonwealth realms, including the United Kingdom.
 The only other time in British history that a monarch celebrated a Diamond Jubilee was in 1897, when Queen Victoria celebrated hers.
St Peter's (Guernesiais: Saint Pierre), known officially as "Saint Pierre du Bois" (English: "St. Peter in the Wood") is a parish in Guernsey.
 It is the centre for the Guernsey Western Parishes which includes Torteval, St Saviour's and the Forest.
Guernsey Dam is an earthfill dam on the North Platte River in Platte County in the U.S. State of Wyoming.
 The dam creates Guernsey Reservoir, the last of the 5 major reservoirs on the North Platte River in Wyoming.
 The dam contains a hydroelectric plant capable of 6.4 megawatts of electricity.
 The total capacity of the reservoir is 71040 acre.ft of water which is used mainly for irrigation.
 Morrison-Knudsen (Now URS Corporation) and Utah Construction Company constructed Guernsey Dam and the hydroelectric plant as part of the North Platte Project to provide irrigation to eastern Wyoming and western Nebraska.
 Guernsey helps control the river flow and stores water released from the project's primary storage upstream at Pathfinder Reservoir.
 About 8 mi downstream of the dam the Whalen Diversion Dam diverts water into the Fort Laramie and Interstate Canals that service farms in Wyoming and Nebraska.
The Framingham Reservoir No. 1 Dam and Gatehouse are a historic water works facility in Framingham, Massachusetts.
 They are located at the end of Framingham Reservoir No. 1, which is also known as the Stearns Reservoir, off Winter Street and north of Long Avenue.
 They were constructed 1876-78 as part of an expansion of the water supply of the city of Boston and were designed by its first city architect George A. Clough.
 The historical purpose of the reservoir, which was located at the confluence of two branches of the Sudbury River, was primarily to control the river's water level, and secondarily to provide reserve supply capacity.
 The reservoir's reserve capacity was generally used only as a backup supply as the reservoir's muddy bottom made it a less desirable source than reservoir 3 upstream.
 However the reservoir no. 1 system was nonetheless important due to its role in controlling the flow of the river downstream and due to the gatehouse which controlled the water flows for all the Framingham reservoirs into the Sudbury Aqueduct.
 Reservoir No. 1 is no longer maintained as a reserve water source, although it is still owned by the Massachusetts Water Resources Authority, successor to the Boston Water Board which oversaw its construction.
 MWRA retains ownership as the gatehouse contains the connection between Reservoir No. 3 and the Sudbury Aqueudct which remain part of the emergency water systems.
Guernsey State Park is a public recreation area surrounding the Guernsey Reservoir, an impoundment of the North Platte River, near the town of Guernsey in Platte County, Wyoming.
 The state park features multiple campgrounds, boat ramps, and hiking trails as well as exceptional examples of structures created by the Civilian Conservation Corps in the 1930s.
 Facilities are managed for the Bureau of Reclamation by the Wyoming Division of State Parks and Historic Sites.
The Lower Peirce Reservoir (Chinese: 贝雅士蓄水池下段 Malay: "Takungan Air Lower Peirce") is one of the oldest reservoirs in Singapore.
 It is located near MacRitchie Reservoir and Upper Peirce Reservoir.
 Previously known as Kallang River Reservoir and Peirce Reservoir, it was renamed Lower Peirce Reservoir after the creation of Upper Peirce Reservoir.
 It has a surface area of 6 hectares and the surrounding forest contains many trees that are over 100 years old.
 There is a Lower Peirce Trail, which is a 900-metre boardwalk that takes visitors through a mature secondary forest.
 The reservoir is the source of the Kallang River, the longest river in Singapore.
Torteval (Guernésiais: Tortévas) is the smallest of the ten parishes of Guernsey, one of the Western Parishes.
 Its name comes from the Guernésiais words for "twisting valley".
 The parish is split in two by the parish of St. Pierre du Bois, with the part in the east known as Torteval.
 The detached peninsula to the west is named Pleinmont-Torteval.
 It includes the westernmost point in Guernsey, and a nature reserve.
 The reserve, designed for birds in the 1970s, was to be redeveloped for the Diamond Jubilee of Queen Elizabeth II in 2012.
Prettyboy Reservoir occupies 206.5 km2 of northern Baltimore County, Maryland, also known as the Hereford Zone.
 Even though the reservoir is located in the county, the City of Baltimore owns the reservoir and the surrounding land of forested watershed.
 The reservoir is one of three reservoirs created to supply the Metropolitan Baltimore municipal water system for Baltimore City, Baltimore County and northern Anne Arundel County constructed by the Baltimore City Department of Public Works.
 Prettyboy Reservoir, along with Loch Raven Reservoir that is downstream on the Gunpowder Falls, provide about 61% of the drinking water for the entire Baltimore Metropolitan system.
 For this reason, the Prettyboy is considered a “source water” or drinking water watershed.
 The reservoir on average contains about 19 e9USgal of water.