Algal blooms also impair the aesthetic qualities of inland waterways and can create odour problems. While the ocean plants discharge higher levels of nutrients during their operations, there is little to no effect on aquatic life or the environment. This is because of the dilution and dispersal that occurs in an ocean environment. Nutrients are also considered beneficial to the diets of ocean fish. Phosphorus and nitrogen are introduced to the waste water stream from a variety of sources in the residential, commercial and industrial customers.
All nitrogen is sourced from people's diets.
Meat and alcohol, in particular, are two main sources of nitrogen in human waste. Sydney Water has spent millions of dollars in upgrading its STPs along the Hawkesbury-Nepean. These upgrades have enhanced biological nutrient removal processes which reduce nutrient levels in discharged effluent. The scheme has been designed as a community right to know initiative and data will be accessible on an Internet database. After this time participation in the NPI is be mandatory.