RAP
viii. Eutrophication or Undesirable Algae
BUI viii Eutrophication or Undesirable Algae
Status: Impaired
What was the original problem? Phosphorus and ammonia concentrations exceeded the requirements for reasonable algae growth in Hamilton Harbour. Algae presented an aesthetic problem with reduced water clarity and fouling the shore. Ammonia and decomposing algae created a high oxygen demand which caused anoxic areas during the summer. This reduced fish habitat and interfered with the normal food chain.
Delisting Guideline: When there are no persistent water quality problems (e.g. dissolved oxygen depletion of bottom waters, nuisance algal blooms or accumulation decreased water clarity, etc.) attributed to cultural eutrophication.
What Has Been Done?
- City of Hamilton is managing Combined Sewer Overflows (CSOs) to reduce amount of untreated sewage entering Hamilton Harbour. Primary treatment capacity has been increased at Woodward Wastewater Treatment Plant
- Halton’s Skyway Wastewater Treatment Plant successfully utilized plant optimization to improve effluent for a number of years
- ArcelorMittal and U. S. Steel Canada (formerly Stelco) dramatically improved their discharges to Hamilton Harbour in the early 1990s through the Municipal-Industry Strategy for Abatement (MISA) program
How Are Things Today?
- The Harbour responds to reductions in phosphorus loading (50% phosphorus loading reduction has been made since 1980s)
- Recent water quality modelling of the Harbour integrates phosphorus and ecosystem conditions and suggests the updated loading targets should lead to meeting the updated environmental goals identified for the Harbour
What Still Needs To Happen?
- Complete tertiary treatment upgrades to Halton’s Skyway Wastewater Treatment Plant
- Initiate tertiary treatment upgrades of Woodward Wastewater Treatment Plant to increase capacity and reduce phosphorus loading
- Implement Real Time Control to improve usage of the Combined Sewer Overflow system
When Will The Status Change?
- Hamilton Harbour has a relatively short residence time so some degree of water quality improvement should be realized quickly following implementation of management actions. A lag in further water quality improvements however, could occur due to release of phosphorus from historically deposited sediments. In addition, ecosystem components linked to the phosphorus goals and targets, such as the number and diversity of aquatic plants, may take longer to respond due to cascading impacts from water quality improvements.
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