Clythe well Environmental Assessment

Schedule ‘B’ Class Environmental Assessment for treatment upgrades

The City of Guelph is looking into possible treatment upgrades to Clythe well to improve the water quality from this supply source.Water from Clythe well does not currently meet the aesthetic objective—or guideline—for hydrogen sulphide (H2S), and this well has been out of production since 1999. Water from Clythe well has an unpleasant odour and taste. When H2S combines with iron in water, it can also cause black stains on laundry, and water fixtures. There is no health-related objective for H2S in drinking water.

Study objectives

The City of Guelph is initiating a Municipal Class Environmental Assessment (EA) for proposed treatment upgrades to bring the Clythe well back into service. The City’s Water Supply Master Plan (2014) identifies the need for additional water sources to support future demand in the northeast area of the city. Clythe Well is identified as a candidate for early implementation. A study conducted in 2011 concluded that water from the Clythe well can be successfully treated with existing technology.

Map shows the area covered by the Clythe well environmental assessment roughly bounded by York Road, Auden Road, Eastview Road and the city's eastern boundary

The process

Planning for this project is proceeding as a Schedule “B” undertaking in accordance with the Municipal Class Environmental Assessment process (MEA, June 2000, as amended in 2007 and 2011), prepared by the Municipal Engineers Association. The Class EA is an approved process under the Ontario Environmental Assessment Act and includes public and review agency consultation, an evaluation of alternatives, an assessment of potential environmental effects of the proposed alternatives, and identification of reasonable measures to mitigate any adverse impacts that may result.

Once a preferred alternative is selected and the EA is approved, the project will move into design. The total anticipated project cost including the EA, design and construction, is about $7 million dollars, pending the approval of future budgets by Council.

Timing and milestones

  • Class EA alternatives identified (field studies): May-August 2017
  • Class EA public open house: September 2017
  • Class EA final draft for public review): November-December 2017
  • Class EA finalized and submitted to MOECC for approval: December 2017
  • Detailed Design: July 2018-June 2019
  • Construction: July 2019-December 2020


One of Guelph’s highest priorities is to maintain a safe, high-quality water supply that meets and surpasses the requirements of all provincial regulations related to drinking water supplies. In delivering safe water to our community, the City aims to use local water resources to support the current and future needs of our growing city. Bringing water supply wells that are currently offline, back online again, is identified as a priority for meeting water supply demands in the City’s 2014 Water Supply Master Plan.

Clythe well in particular has been identified as a City drinking water source that, with treatment upgrades, can be brought back online. The Water Supply Master Plan puts Clythe well back into service as an active water supply well by 2020.


Clythe well was drilled in 1976, and the City maintains a permit to take water at a rate of 61 litres per second from the Ministry of the Environment and Climate Change. The City first put Clythe well into service in 1990.

Naturally occurring hydrogen sulphide (H2S) gave the raw water from Clythe well an odd taste and odour that was initially/successfully treated with aeration and off-gassing.  In 1999, the well was upgraded with a well liner in an effort to block water flowing in from shallower groundwater sources, the suspected source of the H2S. Unfortunately the upgrade didn’t resolve of the H2S problem, and the City took the well offline in 1999.

In 2008, the City completed further testing at Clythe well to determine if the raw water from the well could be if properly treated. The use of manganese dioxide filters along with activated carbon polishing was successful in removing iron, manganese and H2S.

About hydrogen sulphide

Hydrogen sulfide (H2S) is as a colourless gas under normal conditions. This gas occurs naturally in coal, natural gas, oil, volcanic gases, and sulphur springs and lakes. H2S can be found in some groundwater sources but not in surface water sources.

The aesthetic objective for sulfide in drinking water is 0.05 mg/L as H2S; it is an odour-related objective. There is no health-related objective for H2S in drinking water. Low amounts of sulphide likely to be found in drinking water are not expected to produce toxic effects, and ingestion of large quantities of H2S is unlikely because of the associated unpleasant taste and odour.

Water from Clythe well does not currently meet the aesthetic objective—or guideline—for H2S. Water from Cythe well has an unpleasant odour and taste like rotten eggs. When H2S combines with iron in water, it can also cause black stains on laundry, and water fixtures.

Treatment upgrades can bring aesthetic water quality of Clythe well in line with the objective, making this source of drinking water usable once again.

Learn more about H2S and drinking water.

How to participate

The City of Guelph is interested in receiving public input and comments during this project. An open house will be held to review and discuss issues related to this project. Meeting dates and details will be advertised in the City News pages of the the Guelph Mercury Tribune (Thursday editions), posted in the Latest updates tab on this project page, posted in the City’s meeting and event calendar at, and promoted on the City’s facebook and twitter accounts.


Clythe Well Environmental Assessment Open House boards, October 19, 2017

For more information

To provide your comments, request additional information, or to be added to the project mailing list, please contact either:

Robin Puskas, P. Eng.
Project Manager, Water Services
City of Guelph
1 Carden Street
Guelph, ON N1H 3A1
519-822-1260 extension 2195
Grant Parkinson, P. Eng.
Project Manager
GM BluePlan Engineering Limited
650 Woodlawn Road West, Unit C2
Guelph, ON N1K 1B8