| Bill Gunn Dam | |
| Location Map: | Queensland |
| Location Map Caption: | Location of the Bill Gunn Dam in Queensland |
| Coordinates: | -27.6278°N 152.3769°W |
| Country: | Australia |
| Location: | South East Queensland |
| Purpose: | Irrigation |
| Status: | O |
| Opening: | 1987 |
| Operator: | SEQ Water |
| Dam Type: | E |
| Dam Height: | 18m (59feet) |
| Dam Length: | 1160m (3,810feet) |
| Dam Volume: | 722e3m3 |
| Dam Crosses: | Off-stream |
| Spillway Type: | Uncontrolled |
| Spillway Capacity: | 5m3/s |
| Res Name: | Lake Dyer |
| Res Capacity Total: | 6940ML[1] |
| Res Catchment: | 3km2 |
| Res Surface: | 100ha |
| Res Elevation: | 110m (360feet) |
| Res Max Depth: | 10.7m (35.1feet) |
| Res Max Length: | 1100m (3,600feet) |
| Res Max Width: | 600m (2,000feet) |
The Bill Gunn Dam is an earth-fill embankment dam with an un-gated spillway located off-stream in Laidley Heights in the South East region of Queensland, Australia. The main purpose of the dam is for irrigation of the Lockyer Valley.[2] [3] The resultant reservoir is called Lake Dyer.
Located west of the town of Laidley, the dam was developed to increase the capacity of the existing Lake Dyer, a natural lake adjacent to Laidley Creek, a tributary of Lockyer Creek. The dam was named after the Queensland politician Bill Gunn and is managed by SEQ Water.[2]
The 1170m (3,840feet) long earthfill structure has a maximum height of 12m (39feet) and an overflow spillway which diverts excess water into Laidley Creek. The dam has a storage capacity of 6950ML and a maximum surface area of .
Water from the dam is used for irrigation, in the densely cropped Lockyer Valley.[2] Bill Gunn Dam suffers from high drawdowns and summer evaporation which together with phosphate fertilizer creates significant blue green algae problems.[2] In November 2005, during drought conditions in the area, the dam's water level declined to just 1%.[4]
A boating permit is not required, however a maximum of eight boats are allowed on the lake at once.[2] A single concrete boat ramp and some facilities for visitors, including campers, are available at a lakeside caravan park which is managed by the local council.
The dam is stocked with silver perch and golden perch, while bony bream, spangled perch and eel-tailed catfish breed naturally.[2] A Stocked Impoundment Permit is required to fish in the dam.[5] The poor water quality means that fish caught in the dam may, at times of an algae outbreak, be a health hazard if eaten.[2]