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Eutrophication or undesirable algae (BUI #8)

A recent scientific assessment indicates that there are no issues related to excess nutrients or algae in the Niagara River. Following a technical peer-review of the assessment, the RAP Team conducted extensive public engagement on the recommendation to change the status of the BUI. The results of the assessment and review process were compiled into a BUI Re-Designation Report which was submitted to the Canada-Ontario Agreement (COA) Annex 4 Co-Leads in 2018 for formal review. In 2019, the COA Annex 4 Co-Leads officially confirmed and supported the recommendation to change the BUI’s status.

The Eutrophication or Undesirable Algae BUI is no longer considered impaired for the Niagara River.

Why is algae used as an indicator?

Algae are plant-like microorganisms that live in water. They are an important part of the food chain as the main source of food for zooplankton and planktivorous fishes. Algae occur naturally but when there are too many nutrients (like phosphorus) in water (from fertilizers, soaps, and sewage), algae can grow out of control (called an algal bloom). When large amounts of algae die, they us up important oxygen which can kill fish or wildlife. Some algae are toxic and can cause serious illness to humans and wildlife. An algal bloom is an indicator of nutrient pollution.

According to information on the International Joint Commission website, this beneficial use impairment (BUI) applies when there are persistent water quality problems linked to excessive nutrients from known (point) and unknown (nonpoint) sources. Typically, the impairment is observed as nuisance or harmful algal blooms, depleted oxygen levels in bottom waters, and decrease water clarity (source: IJC).


Status of BUI Over Time

  • 1985: An IJC assessment  indicated that the Niagara River did not suffer from eutrophication.
  • 1993 (Stage 1 RAP Report): Not Impaired for Niagara River; Impaired for Welland River  (a tributary of the Niagara River)
  • 2009 (Stage 2 RAP Update):  Based on anecdotal evidence of eutrophication in the Welland River, the BUI status was changed to ‘Impaired’ for the entire AOC despite the Niagara River not showing signs of impairment.
  • 2019 (BUI Re-Designation Report): Not Impaired

Science & Monitoring

A detailed assessment of the BUI was completed in the Niagara River (Ontario) AOC using a multiple-lines-of-evidence approach. The findings suggest there are no issues related to excess nutrients or algae in the Niagara River.

  • Total phosphorus (TP) concentrations were evaluated against the Provincial Water Quality Objective (PWQO) criterion of 30 ug/L. The review identified that some values exceeded the PWQO likely due to known sources upstream of the Niagara River AOC. TP concentrations upstream and downstream in the Niagara River showed no significant difference, suggesting minimal sources of TP within the AOC.
  • Phosphate and chlorophyll a concentrations were generally equivalent to or less than those measured in comparable reference areas;
  • Dissolved oxygen (DO) concentrations were generally above the screening criterion of 6.5 mg/L. Of the two DO observations below 6.5 mg/L, impact to biota was not expected;
  • Historical Secchi disc depth values in the Niagara River were generally on par with or better than current day values in comparable reference areas;
  • The BUI is listed as “Not Impaired” on the New York side of the Niagara River because of declines in phosphorus and chlorophyll a levels in Lake Erie between 1968-1985, high levels of DO, and the absence of nuisance algal blooms.
  • Environment and Climate Change Canada (ECCC) continues to monitor water quality in the Niagara River through its Upstream-Downstream water quality monitoring program.
  • Water quality monitoring is ongoing in the Welland River by the NPCA through collaborations with the City of Hamilton, Niagara Region,  ECCC and Ontario Ministry of Environment and Climate Change.


What is left to do?

No further studies/remedial actions are required.

Related Remedial Action Activities

Most of the restoration efforts and studies prior to 2012 were focused on the Welland River and its watershed. Due to the revised GLWQA of 2012, the scope of all the AOCs was refined to ensure targeted restoration in the Waters of the Great Lakes; therefore, the Welland River and its watershed is no longer considered a part of the AOC itself but is recognized a potential source to impaired water quality in the Niagara River (as the AOC watershed). We recognize all of the important work conducted in the Niagara River as well as its tributaries. Below is a list of related activities done by all RAP partners:

  • In 2018, a BUI Re-Designation Report was prepared and submitted to the Canada-Ontario Agreement Annex 4 Co-Leads for review and concurrence on the status change to ‘Not Impaired’.
  • A scientific assessment of the BUI was conducted by technical staff at the Ontario Ministry of Environment, Conservation and Parks (MECP) (with the RAP Team preparing the background information) in 2014. The draft technical assessment report was peer-reviewed in 2014 and revised as needed. The final report (2015) recommended changing the BUI to “Not Impaired”. Extensive public engagement was conducted to obtain feedback on the recommended status change.
  • In 2012 the NPCA monitored the existing water quality stations in the Welland River watershed to track (temporal & spatial) nutrient concentrations and other water quality parameters. Eight samples were collected monthly at each sampling station beginning in April 2012. Two sub-watersheds (Beaver Creek and Big Forks Creek) of the Welland River were identified as contributing very high phosphorus loads to the Welland River watershed through the Welland River Eutrophication Study. In order to focus restoration efforts within these watersheds, the MOE and NPCA completed a nutrient track down to identify nutrient sources. MOE and NPCA staff identified fourteen water quality sampling stations in the Big Forks Creek and Beaver Creek watersheds. These stations were sampled biweekly by MOE and NPCA staff starting in March 2012 and concluding in November 2012. The MOE lab completed sample analysis and their staff analyzed the data for the project.
  • The NPCA’s GIS restoration database (initiated in 1991) contains data on restoration project types (Non-Point Source) and locations within the Welland River watershed.
  • In 2012, the NPCA initiated new water quality monitoring in the Lower Welland River watershed, the Chippawa Power Canal, and other non-Welland River tributaries to characterize the nutrients and other water quality parameters.
  • The NPCA produced technical reports (2009, 2010 and 2011) to summarize the results of the Welland River Eutrophication Study.
  • In 2007, the RAP initiated the Welland River Eutrophication Study and established a multi-agency Technical Working Group (TWG) to carry out enhanced water quality sampling during 2008, 2009 and 2010 to specifically study the issue of eutrophication in the Welland River watershed (which was considered part of the AOC during that time). The monitoring continued during 2012 in the Welland River and tributaries with support from the Ontario Ministry of Environment and Environment and Climate Change Canada’s Great Lakes Sustainability Fund.
  • In 2007, the Niagara Region and the City of Niagara Falls completed the construction of a new joint Central Pump Station – High Rate Treatment facility, eliminating the Muddy Run Combined Sewer Overflow (CSO) discharge to the Niagara River and significantly reducing CSO volume city-wide.
  • The City of Welland completed Pollution Control Plan studies and implemented infrastructure upgrades (projects of interest to the RAP are identified in the City’s 5-year Sanitary Sewer Work Plan (2011-2015).
  • The City of Welland’s Official Plan (2010) incorporated RAP supported policies for urban stormwater runoff & reduction of CSOs.
  • Until 2017, the NPCA’s Water Quality and Habitat Improvement Program provided cost-share grants to private landowners to improve water quality in the watershed. Example projects included fencing to keep livestock out of creeks, manure storage to prevent runoff, etc.
  • A draft Environmental Assessment for a proposed High Rate Treatment facility at the City of Welland’s Sewage Treatment facility is under review (reported by Niagara Region’s project manager in Nov/12).
  • The municipality of Queenston sought approvals for implementation of total phosphorus treatment to address issues with its Wastewater Treatment Plant (2012).

The Bi-National Connection

This BUI is listed as ‘Not Impaired’ on the New York, USA side of the Niagara River. Learn more about the restoration efforts on the U.S. side of the Niagara River: https://www.epa.gov/great-lakes-aocs/about-niagara-river-aoc

About Us

Efforts from many key partners in the RAP Team continue to help complete priority actions for the restoration, protection, and enhancement of the Niagara River ecosystem. This initiative is made possible through the financial support of the Government of Canada and Ontario, in partnership with the Niagara Peninsula Conservation Authority.

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