Visitors to the Mulloon catchment in the NSW Southern Tablelands view the treated creek with its stable, well-vegetated ponds and stable banks and are convinced that our landscape rehydration methods work. Yet a persistent doubt – based on a misperception that instream bed-control structures equal dams, is that water flowing downstream would be diminished. We can now safely report that this is not the case.
Mulloon Institute has released a 94-page report on the Home Farm, detailing climate, hydrological and groundwater data, which was analysed between 2006 and 2020. The Home Farm reach of Mulloon Creek is the site of the pilot program initiated by Tony Coote and Peter Andrews with instream bed control structures (‘leaky weirs’) installed in 2006.
Prepared by Associate Professor Leah Moore and Tony Benardi, the report presents crucial background information describing the intensive monitoring regime and data tracking the performance of the Mulloon Rehydration Initiative, now with installation of multiple structures and associated works right along the creek, with complete coverage to be completed over the next few years. A complex array of monitoring equipment and surveys is in place, tracking the impact and effect of the rehydration interventions (see Peel et al 2022 for detail).
The report covers a range of climate, hydrological and groundwater variables, focusing on the impact of works in the Home Farm reach on flow into and then from the treated stream reach, the report states that (emphasis added):
The establishment of in-stream ponds does not decrease the downstream flow volume with relatively low average flow into the mid-Mulloon Creek catchment (Black Jackie gauge <<200 ML/day; daily stage <0.5m) and higher average flow from the mid-Mulloon Creek catchment (Mid-Mulloon gauge 100-300 ML/day; daily stage 0.5-0.75m).
The 94-page report (plus online appendices) also notes the stabilising effect of the vegetated banks of the pond systems as a guard against erosion, stable water quality, and other matters. The Institute is currently analysing other monitoring data, including fish, frogs, aquatic invertebrates and structure integrity (which required a whole new method), and we will be reporting results in the near future.