Despite these issues, Canning Dam and the adjacent parks and forests provide a variety of recreational activities for the public such as bushwalking, historic walks and picnic facilities.
[3] However, despite the recommendations of further inquiries, and an extreme shortage of water in some years, government funds were not allocated for the construction of a dam until the Great Depression in the 1930s.
It was intended as only a quick fix to the water supply problem and it soon became apparent that a major reservoir was needed, although it was nine years before work on the current Canning Dam began.
[1] A further improvement was made in 1951 when a concrete-lined channel was constructed to divert stream flow from the nearby Kangaroo Gully catchment.
The Canning Dam Catchment lies within the Darling Scarp which forms part of an Archaean Shield composed largely of granite with some invaded linear belts of metamorphosed sedimentary and volcanic rocks.
[8] The dam wall is situated in a narrow gorge running east and west, with rock sides sloping upward from the river bed.
[8][9] The construction of Canning Dam ended a long period during which Perth's water supply was generally unsatisfactory in quality (either due to salinity or bacterial pollution or both) and in quantity.
[1] Near-vertical tubular 8-inch (200 mm) cut-off drains were provided at 5-foot (1.5 m) intervals along the dam to relieve internal seepage through the concrete.
While state of the art materials-handling methods were used, in some instances labour-saving machinery worked beside operations intended to maximise the labour content.
Sustenance workers were employed for chiefly on-site preparation, road construction, foundation excavation, clearing timber from the reservoir basin, and on some concreting operations.
The final cost of the dam was significantly less than had been originally budgeted for,[3] and the work was completed on schedule to a date that was calculated seven years previously.
Finally, permanent, re-stressable ground anchors were installed through the formed and drilled holes from the crest to be stressed and grouted into the foundation rock.
[13] An innovative drilling and blasting technique called penetrating cone fracture (PCF) was used in the remedial works process.
PCF was chosen over conventional drilling and/or blasting techniques due to the reduced risk of damage to the existing structure from vibration, as well as lower noxious fume and dust levels.
[17] Damming of the Canning caused dramatic flow reductions that significantly altered downstream aquatic macroinvertebrate communities.
[8] Canning Dam features a number of picnic areas (with gas barbecues), look outs and historic walks – many with disabled access.
Several mountain bike trails run either through the Canning National Park or adjacent State Forest areas.