North Dandalup Dam facts for kids

Quick facts for kids North Dandalup Dam
The dam seen from the northern lookout point
Country	Australia
Coordinates	32°31′03.61″S 116°00′59.04″E / 32.5176694°S 116.0164000°E / -32.5176694; 116.0164000

North Dandalup Dam is a dam in Western Australia. It is located 63.8 kilometres (39.6 mi) south of Perth in the Darling Scarp, which forms the western border of the Darling Ranges. Constructed in 1994, it was opened by the then state Premier Richard Court in October of that year. It was the final project in a dam-building scheme that also includes the Victoria and Conjurunjup Dams.

The dam, described by the Water Corporation as "a strategic source of public drinking water for the Integrated Water Supply System (IWSS)," provides water to Perth, Mandurah, Pinjarra, Harvey, the Goldfields and agricultural supply, and has in the past accounted for 10% of Perth's annual water supply.

Capacity

The $50 million project, with a capacity to hold 75 gigalitres (2.6 billion cubic feet), has at its peak, held 59.85% of capacity in 1996, with it reaching a minimum of 16.39% as of 2011. It has a catchment area of 153 km² (59 sq mi), with 510 hectares (1,300 acres) of surface area at full storage. There is a total system yield of 22 gigalitres (0.78 billion cubic feet) per annum as of 2009, an increase from 19 gigalitres (0.67 billion cubic feet) per annum in 2005.

Layout

Main Dam

The dam is 62 metres (203 ft) high and 192 metres (630 ft) long.

Other dams

There are two earthfill saddle dams on low lying ridges slightly to the northwest, next to the main dam, the larger is 22 metres (72 ft) high, and the smaller is 9 metres (30 ft) high. Between these dams, there is a lookout which provides a view of Mandurah, the Peel inlet, and the Indian Ocean. There is another dam, the original Pipehead dam, built in 1971, which is now open for recreational use. In this recreational area, there are facilities such as barbecues, toilets, picnic tables and parking.

Environment

Flora & Fauna

The surrounding area contains a variety of flora and fauna, with the vegetation predominantly consisting of jarrah (Eucalyptus marginata), marri (E. calophylla) and wandoo (E. wandoo). Wildlife consists of kookaburras, long-billed cockatoos, and the Scarlet Robin.

Geology

The dam forms part of the Archaean Yilgarn block, consisting of mainly granitoid rock with dolerite dykes and is capped with laterite.

Water Quality

According to a Water Corporation study shown in the table below, the dam contains low levels of metals and inorganics, and the only pesticide present is Simazine, present in only one sample in levels well below Australian Drinking Water Guidelines (ADWG). A 2005 protection plan also by the Department of Environment showed there are risks of pathogen contamination, turbidity, pesticides and nutrient contamination, with pathogens being the most severe possibility, but turbidity being the one with the highest possibility of occurring.

Before water is supplied to the Integrated Water Supply System (IWSS), it is disinfected by chlorination and then fluorinated. Microbial testing is conducted on a weekly to monthly basis, depending on the season.