Sandy Creek, early January
What a summer! Rain through December and January, pastures green late into summer and native grasses flourishing. Then in February, we had sighting of a platypus in Riddells Creek, at the weir right there on the edge of town --- good streamflow means platypus are able to move around and get upstream.
Looking ahead the picture is not so rosy. Average annual rainfall in the Maribyrnong catchment is down by 17% since 1975, and the Sustainable Water Strategy estimates 20-40% less streamflow by 2065. Instream biota and edge of stream life all depend on flow. They have evolved around the rise and fall of seasonal flow, and big storm events, but drop the flow permanently and our creeks struggle.
Water extraction in Macedon for gardens and for what are arguably ornamental dams compromises streamflow in Riddells Creek. Diversion into reservoirs that once supplied each town around the Macedon range compromises flow. The failure to mandate an Environmental Flow for the Maribyrnong compromises flow, and engineering that only allows a trickle out of Rosslyne Reservoir locks low flow in place for Jacksons Creek.
Flip to the other side of the equation, and Riddells Creek sewerage treatment is close to capacity. There were no big ticket capital works for Riddell in Greater Western Water’s recent Pricing Submission to the Essential Services Commission. When I asked GWW for their population projection for Riddells Creek, they put me on hold, but if they are using the last State Government estimate of 5982 by 2036, they are in for a surprise - development planned in Riddell might see us at 8000 by 2036.
That could bring incidents like those on the Coliban and on Deep Creek at Romsey, where discharge breaches EPA licence conditions. For Jacksons Creek and Deep Creek, where flow is already severely compromised, unexpected discharge might put a load on the creek that it can’t handle.
The Water Think Tank is a network of community members who care about what is happening to our creeks. We want to understand how water is managed, so we can give informed opinion on water issues. More people and less water means we need to think ahead.
Our April session goes to Garden Hut Reservoir on the north side of the range to consider the impact on extraction for Garden Hut Creek, and downstream, for Deep Creek.
Get in touch with me ross.colliver@bigpond.com if you want to hear more.
Ross Colliver, Riddells Creek Landcare