The Glenmaggie Dam is a concrete block foundation gravity dam with 14 radial arm gates across the Macalister River, located near Maffra, Central Gippsland, in the Australian state of Victoria. The dam's purpose includes irrigation, the generation of hydro-electric power, water supply and conservation. The impounded reservoir is called Lake Glenmaggie.

Glenmaggie Dam
Downstream face.
Location of the Glenmaggie Dam in Victoria
Country	Australia
Location	Sale, Central Gippsland, Victoria
Coordinates	37°54′17″S 146°48′00″E
Purpose	Irrigation
Status	Operational
Construction began	1919
Opening date	1927
Owner(s)	Southern Rural Water
Dam and spillways
Type of dam	Gravity dam
Impounds	Macalister River
Height	37 m (121 ft)
Length	295 m (968 ft)
Elevation at crest	77 m (253 ft) AHD
Width (crest)	99 m (325 ft)
Dam volume	77×10^3 m3 (2.7×10^6 cu ft)
Spillways	2
Spillway type	Uncontrolled
Spillway capacity	3,400 m3/s (120,000 cu ft/s)
Reservoir
Creates	Lake Glenmaggie
Total capacity	190,410,000 m3 (6.724×109 cu ft)
Active capacity	177,628,000 m3 (6.2729×109 cu ft)
Inactive capacity	4,860,000 m3 (172,000,000 cu ft)
Catchment area	1,891 km2 (730 sq mi)
Surface area	1,760 ha (4,300 acres)
Glenmaggie Power Station
Commission date	1994
Turbines	2 x Francis-type
Installed capacity	4 MW (5,400 hp)
Annual generation	9 GWh (32 TJ)
Website Glenmaggie Dam at Southern Rural Water

Location and features

Construction of the Glenmaggie Dam commenced in 1919, was completed in 1927 and constructed by the State Rivers and Water Supply Commission of Victoria. When full following its construction, the dam held 132,000 megalitres (4,700×10^⁶ cu ft)[1] and provided irrigation to approximately 360 square kilometres (140 sq mi) of farming land in the Central Gippsland region; via a gravity irrigation systems to properties in the Macalister Irrigation District, near the towns of Maffra, Heyfield, Stratford and Sale. The Macalister Irrigation District covers about 53,000 hectares (130,000 acres) around the Macalister and Thomson rivers, extending from Lake Glenmaggie to Sale. It comprises two areas: the Maffra-Sale Irrigation Area to the north of the Thomson River and the Central Gippsland Area (including the Nambrok-Denison Soldier Settlement district) to the south.[2]

The Glenmaggie Dam wall, which creates the Glenmaggie Lake, is a mass concrete overfall dam with irrigation outlets on both sides of the river serving irrigation channels. The central portion is an overfall spillway.[2] The dam wall was raised in 1958 by the addition of gates; stabilised using ground anchors in 1989;[3] and upgraded in 2003 to enable it to withstand overtopping.[2]

In 1994, a hydro-electric power station with two Francis turbine-generators was commissioned, with a capacity of 4 megawatts (5,400 hp) and generating 9 gigawatt-hours (32 TJ) per annum.[3][4]

Flooding

In June 2007, the Macalister catchment experienced record flooding. Inflows into Lake Glenmaggie peaked in excess of 250,000 megalitres (5.5×10¹⁰ imp gal; 6.6×10¹⁰ US gal) per day and releases peaked at 147,000 megalitres (3.2×10¹⁰ imp gal; 3.9×10¹⁰ US gal) per day. A second flood occurred in November 2007 with inflows into Lake Glenmaggie peaking at 70,000 megalitres (1.5×10¹⁰ imp gal; 1.8×10¹⁰ US gal) per day and releases peaking at 59,000 megalitres (1.3×10¹⁰ imp gal; 1.6×10¹⁰ US gal) per day. Repairs totaling around A$4 million were completed after the June and November 2007 floods.[1]

See also

• Irrigation in Australia
• List of dams and reservoirs in Victoria

References