Water Quality in the Canals


PGLOA was privileged recently to be given access to the 2021 Port Geographe Water Quality Report. 

Key observations:

  • Sampling has been carried out at multiple sites since 2016 (including the Lagoon).
  • Sample sites can be broadly grouped as upper waterway, lower waterway (includes Lagoon) and reference sites (in Geographe Bay).
  • Tests included pH, Phosphorous, Nitrogen, Chlorophyl-a, E Coli, Turbidity, Dissolved O2, Phytoplankton, Odour, Cyanobacteria.
  • There is a general trend of improving water quality from 2016 to 2021.
  • Water quality varies depending on time of the year. 
  • Swimming at the designated beaches within Port Geographe is acceptable from a water quality perspective.  Swimming in the canals elsewhere is not recommended by DoT as they are navigable waterways (boating safety rather than for water quality reasons).
  • Overall water-quality results in the Lagoon are similar to those in other canals. The least favourable results for the Lagoon were for chlorophyl-a and odour.  This is attributed to birds roosting on the breakwater, and restricted flushing when seagrass wrack accumulates in the main canal channel where the Lagoon joins the main canal.
  • The chief recommendation to improve water quality at Port Geographe is to mobilise the dredge earlier (early Spring) each year so flushing of the waterways is not impeded by seagrass blocking the main channel.