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East Ottawa – Champlain Groundwater Study

East Ottawa – Champlain Groundwater Study

Project Background
City staff measuring water alkalinity using a field titration kit

The City of Ottawa and the United Counties of Prescott and Russell (UCPR) have partnered with the Ontario Geological Survey and South Nation Conservation Authority to study groundwater in East Ottawa and Champlain Township. The objective of the study is to develop maps of expected groundwater quality to help support development planning.

City staff filling sample bottles at a field site
Geological Setting

The chemistry of groundwater varies across the study area and depends on several factors that include the local geology, the composition of the rock and soil underground, groundwater flow patterns and near-by land uses.  In Eastern Ontario, naturally-occurring groundwater quality with concentrations above Ontario Drinking Water Standards, Objectives or Guidelines can occur due to the marine (salt water) environment that existed in the St. Lawrence lowlands following the most recent glacial period over 10,000 years ago. Parts of Eastern Ontario were covered by the Champlain Sea, which deposited up to 40 metres of marine clay. The thick clays act to trap salt water for a long period of time; some of the groundwater in the study area were assessed to be more than 10,000 years old.   In addition, the marine clay covers complex bedrock layers of limestone and shale that may also contribute to poor water quality. Some areas of Eastern Ontario have groundwater with the following chemistry: brackish to saline water; elevated sodium, chloride, iodide and fluoride; elevated pH; and elevated methane. 

Study Area

The East Ottawa – Champlain Groundwater Study boundary is shown in Map 1 (below). Within the City of Ottawa, the Study Area includes Ward 19 (Cumberland) and the eastern portion of Ward 20 (Osgoode).  The western boundary of the study area within Ottawa is the Gloucester Fault; generally groundwater has better drinking water quality on the west side of the Gloucester Fault. 

Study area location. The study area includes the east portion of the rural Ottawa and the Township of Chaplain in the United Counties of Prescott and Russell
Study area location. The study area includes the east portion of the rural Ottawa and the Township of Chaplain in the United Counties of Prescott and Russell

This study is a continuation of two previous studies within the UCPR in the City of Clarence‑Rockland (pilot study, 2013-2016) and the Township of Alfred and Plantagenet (2015-2017).  Ottawa and Champlain are located directly to the west and east of the previous study areas.  This study will broaden the understanding of groundwater in Eastern Ontario within the former Champlain Sea Basin.

2017 Well Water Sampling Program
City staff opening the well cap of a drilled well

A field program to sample raw (untreated) well water from existing private wells was conducted between June 2017 to August 2017 as part of the East Ottawa-Champlain Groundwater Study.   Well sampling was conducted at a two kilometre scale to establish an even distribution across the study area; the objective was to sample one drilled (deep) well from every two-kilometer grid block and one dug (shallow) well from every two two-kilometer grid blocks. The project was advertised (fliers, posters, newspaper ads) prior to the field season and volunteers were selected on a first-come, first-served basis.

The purpose of the sampling program was to collect high-quality groundwater chemistry information to support aquifer mapping, determine groundwater age and interpret groundwater flow patterns.    The groundwater sampling methods applied in the study follow those developed by the Ontario Geological Survey as part of the Ontario Ambient Groundwater Geochemistry Program.

City staff measuring the water level of a large-diameter dug well using a water level tape

Well Water Sampling Program at a glance

  • 775 local residents volunteered to participate
  • 239 groundwater wells were sampled
  • 165 wells were sampled in East Ottawa (121 drilled wells, 44 dug wells)
  • 74 wells were sampling in Champlain Township (54 drilled wells, 20 dug wells)
  • 82 chemical, bacteriological and field parameters were analysed from each groundwater sample

 

Map showing the location of wells sampled in east rural Ottawa. Black points identify drilled (deep) wells and white points identify dug (shallow) wells.
The map shows the location of wells sampled in east rural Ottawa. Black points identify drilled (deep) wells and white points identify dug (shallow) wells. The 2 km sampling grid overlays the map, shown in yellow.

A summary of the field work completed as part of the East Ottawa–Champlain Groundwater Study can be found in the following publication:

T. Di Iorio, M. Melaney, S. Foubister and S.M. Hamilton, 2017.  East Ottawa–Champlain Groundwater Study.  In Summary of Field Work and Other Activities, 2017, Ontario Geological Survey, Open File Report 6333, p.27-1 to 27-8. 

Next steps

Well water sampling results will be available to well volunteers in spring 2018; all volunteers will receive a copy of the chemical results from their untreated well water and a summary report.  

Groundwater maps and a final report are anticipated by late 2018.  Please visit this webpage for future updates!

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