Forest and Barkers creeks flow into Castlemaine where they join to become Campbells Creek, which then flows south to Guildford where it joins the Loddon River.
Campbells Creek, like many lowland waterways in south-eastern Australia would have flowed through a relatively narrow floodplain formed by millenia of slow erosion and deposition of organic matter by wetland plants. This process produced a dark, almost black coloured silty soil. This soil formation is still visible in one location along the creek.
The waterway would have consisted of a “chain of ponds” formation as described by Joseph Parker. Except after heavy rain, the creek’s flows between the waterholes would have been through shallow swampy areas dominated by wetland vegetation.
The entire catchment would have acted like a sponge, storing rainfall in deep organic rich soil and releasing it gradually. Campbells Creek was probably a semi-permanent stream, with flow only ceasing in the worst droughts. Even then, subsurface and groundwater flows would have kept the waterholes filled.
Water quality would have been superb as the vegetation cover throughout the catchment would have ensured that erosion and consequent sedimentation in the creek would have been an extremely rare event, only occurring after extreme weather events.
From the 1850s goldrush onwards, the creeks and the entire catchment have suffered enormous changes.
- Mining for gold saw much of the topsoil washed away, enormous quantities of silt and sludge washed into the creeks and toxins like Arsenic and Mercury mobilised or introduced.
- Each tributary’s flow is disrupted by a large dam (Barkers Creek Reservoir and Expedition Pass Reservoir).
- Hundreds of small dams exist in the catchment
- Much of the catchment is private land, used for agriculture or intensive horticulture.
- Urbanisation in Castlemaine means large areas are paved.
- The larger villages (Maldon, Newstead, Harcourt, Chewton) are now sewered like Castlemaine. All this sewage is now released into Campbells Creek after treatment.
Pre-colonisation, Campbells Creek was probably a permanent stream, with flow only ceasing in the worst droughts. With the changed catchment condition, establishment of dams and a warming and generally drying climate, flows now cease in most years. However, downstream of the waste water treatment plant, we have all year flows that allow aquatic fauna to survive.
Our members advocate to improve the stream flow regime and for better water quality. We encourage Council, designers and developers to retain water in the landscape where possible, as progressive municipalities now practice, in place of traditional paved, piped and drained approaches. We believe one of the major causes of poor water quality is Castlemaine’s storm water inputs. Following moderate rainfall events, stream water turbidity above Castlemaine is good, but downstream of Castlemaine, it’s often very poor.
We encourage Mount Alexander Shire Council to implement stormwater retention basins and litter traps. These can improve both water quality and the stream flow regime.
We also work with Coliban Water, aiming to improve the quality of effluent.
Our work on revegetation and weed reduction means Campbells Creek now supports a surprisingly good range of aquatic macro-invertebrate species in high numbers, at least downstream of the effluent discharge point. These creatures support resident populations of platypus and rakali (native water-rat).