Assessment of Port Owen dredging activities on the Berg Estuary fish and macrobenthos communities: 2023 monitoring report

Anchor were appointed by Port Owen Marina Authority (POMA) to undertake an assessment of POMA marine dredging activities on the Berg estuary fish and macrobenthos communities. 

POMA was granted Environmental Authorisation (EA) for disposal of dredge material into the Berg River, in the form of a General "Dumping" Permit to dispose of dredged material at sea, and a Coastal Waters Discharge Permit (CWDP).  The provincial EA and the national CWDP require surveys of fish and benthos community structure in the reaches of the Berg River Estuary that are affected by disposal of dredge material, but do not specify the timing or frequency of the monitoring. To address the requirements of the EA, Anchor started ecological monitoring to be undertaken on an annual basis at the end of the low flow season each year (i.e., March/April).  The results presented suggest the disposal regime is not having a detectable impact on fish and macrofaunal communities downstream of the disposal site in the lower Berg.  The recommendation is, however, upheld that, given that the dredging operation is an ongoing activity, that monitoring of fish and macrofaunal communities should undertaken on an annual basis.  This is to account for gradual changes over time in environmental conditions that might occur from repetitive dredge disposal, despite current mitigation regarding of the release of dredge material, and to identify these impacts as soon as possible through regular monitoring.