With the full commissioning of Stage 1 in end 2001, about 600 tonnes of sewage sludge are prevented from entering Victoria Harbour every day and it has brought about substantial improvements to the water quality of the Harbour including:
- An average increase of about 10% of dissolved oxygen (vital for marine life) in the harbour waters, bringing benefits to marine ecology.
- The levels of key pollutants in the harbour waters have generally decreased:
- Ammonia (toxic to marine life) has declined by 25%;
- Total inorganic nitrogen and phosphorus (nutrients. which in rich supply can increase the likelihood of red tides) have reduced by 16% and 36% respectively; and
- The overall E.coli level (an indicator of disease-causing micro-organisms) has reduced by some 50%.