Lar Dam

Lar Dam bridge
Lar Dam bridge
Coordinates	35°53′21″N 51°59′48″E
Characteristics
Width	13 m
Location

Lar Dam
Lar Dam
	Lar Lake
	Location of Lar Dam in Iran
Country	Iran
Location	Mazandaran, Amol county
Coordinates	35°53′21.58″N 51°59′45.54″E
Purpose	Water supply, power
Status	Operational
Construction began	1974
Opening date	1982
Owner(s)	Regional Water Company
Dam and spillways
Impounds	Lar river
Height	105 m (344 ft)
Length	1,150 m (3,773 ft)
Width (crest)	13 m (43 ft)
Width (base)	800 m (2,625 ft)
Spillway capacity	1,160 m3/s (41,000 cu ft/s)
Reservoir
Total capacity	960,000,000 m3 (778,285 acre⋅ft)
Power Station
Commission date	Kalan: 1998; Lavarak: 2012-2013
Turbines	Kalan: 3 x 38.5 MW Francis-type ; Lavarak: 2 x 23.5 MW Francis-type
Installed capacity	Kalan: 115.5 MW; Lavarak: 47 MW
	Website; https://thrw.ir/st/73

Lar Dam (Persian: سد لار sad-de lār) is a dam located at the foot of Mount Damavand in Amol county, Mazandaran, Iran. The dam is located within the protected Lar National Park, and situated just 70 kilometers northeast of the capital and the most populous city of the country, Iran. The primary purpose of the dam is municipal water supply to Tehran but prior to the water reaching the city filtration plant, it is used to power the Kalan and Lavarak Hydroelectric Power Stations, with a combined installed capacity of 162.5 MW.

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The construction began on the dam in 1974, and ended four years later in 1981. When the reservoir began in 1980, leakage was discovered downstream. The leakage is due to a karst foundation. The foundation was grouted from 1983 until 1989 with no success.^[1] With the population growth occurring in Amol, there was a need for more water and energy. The ideal place for the dam was over the Lar river, in the northeast section of the city, at the elevated heights of the Kalanbasteh mountain on the slope of Mount Damavand. The area is called Polour, and operations began in 1984.

One of the aims for building the Lar dam was to supply part of Amol with drinking water; it was not possible initially to operate the dam at its nominal capacity, because of a water seepage problem. Water stored in the dam's reservoir is first transferred to the Kalan Power Station (35°48′24.87″N 51°47′29.46″E) then to the Lavark Power Station (35°48′34.97″N 51°44′54.67″E), a distance of 3 kilometers from the Latyan Dam's reservoir, through the 20 kilometer long Kalan tunnel (3 meters in size). After electricity generation, the water joins and feeds the Latyan dam's reservoir. The Kalan Power Station was commissioned in 1998 and the Lavarak in March 2012 and July 2013.^[2]

Uncontrolled growth and expansion of Tehran created a situation where the existing water resources at Karaj, Latyan and Lar dams and the deep wells which were supposed to be exploited only in the during the peak water consumption period. These were no longer capable of meeting the city's water demand, so inevitable abstraction from ground resources started to increase in a manner that at the present situation, the quantity of drilled deep wells has amounted to 230 rings. In fact, from 1997-2000, it had been orderly abstracted, 317, 289, 374 and 357 MCM (million cubic metres) of water from groundwater resources of the city.^[3]