Colac Quarry Monitoring

Client: Holcim Australia and Readymix Australia

Location: Colac Quarry, VIC

Date: 2006 – ongoing

Services provided

• Annual population monitoring of Corangamite Water Skinks.
• Management plan for Corangamite Water Skinks and native vegetation offsets.
• Review of ten years of monitoring.
• Working safely in an active quarry worksite.
• Monitoring constructed sink habitat.
• Monitoring and mapping weeds.
• Annual reporting on survey outcomes for management plan compliance.

Background

Colac quarry is an active stone quarry located north of Lake Colac, producing aggregates and road base. The quarry supports a population of the threatened Corangamite Water Skink Eulamprus tympanum marnieae, which inhabits flooded sections of the quarry where stone has been extracted. Biosis has been engaged since 2006 by various proprietors of the Colac Quarry to conduct annual monitoring of the Corangamite Water Skink.

In 2006 Biosis conducted targeted surveys to establish baseline information of the population of Corangamite Water Skinks discovered at the quarry. We subsequently prepared a management plan for the Corangamite Water Skink and native vegetation offsets, to facilitate stone extraction in the southern extent of the quarry. The plan included ten years of annual Corangamite Water Skink monitoring, which Biosis conducted from 2008 to 2018.

In 2021 a new management plan for extraction in the northeast of the quarry was approved, outlining requirements for further annual surveys. Biosis conducted the first two years of surveys in early 2023 and 2024.

Outcome

Following the ten years of Corangamite Water Skink surveys, Biosis conducted a review of the survey outcomes and determined that the quarry did not appear to have a negative effect on the skink population, and that once the mined sections of the quarry become flooded it’s likely that the population can expand into the created habitat. Observations from the recent 2024 monitoring have reinforced these findings, with several skinks recorded in flooded sections of the recently extracted southern quarry.

Biosis continues to play a key role in effective management and monitoring of the Corangamite Water Skink, and their habitat at the Colac Quarry. Biosis has produced numerous annual outcome reports to the satisfaction of the quarry proprietors and regulatory authorities, including the Department of Energy, Environment and Climate Action (DEECA). Annual monitoring for extraction in the northeast of the quarry is ongoing.