Groundwater monitoring is the routine measurement of water levels, water quality and taking volumes that permits, approvals and planning conditions require, along with the annual reports that interpret it. In Ontario it ranges from baseline private well surveys before a water taking starts, to years of monitoring under a Permit to Take Water or an Environmental Compliance Approval. Programs are designed and reported by a licensed hydrogeologist (P.Geo.) or professional engineer (P.Eng.).
The obligations that set the program
| Source of the obligation | What it requires |
|---|---|
| Permit to Take Water | Collect and record daily volumes and submit them by March 31 for the previous year (O. Reg. 387/04, s. 9), including a "no taking" report (MECP, Permits to take water: operating your permit). Permit conditions often add water level, quality and reporting requirements. |
| EASR water taking registration | Daily volumes recorded and reported by March 31; for construction dewatering, records such as daily rates and volumes from each dewatered work area kept for five years (O. Reg. 63/16, s. 10; MECP water taking user guide for the EASR). |
| Planning approvals | Pre-development monitoring to establish seasonal high groundwater; post-development monitoring where conditions of approval call for it. |
| Environmental Compliance Approvals | Approvals can include groundwater or surface water monitoring conditions; check the approval itself. |
Designing a groundwater monitoring program
For long-term water takings, the ministry's Category 3 guidance describes what a monitoring plan should identify:
- the number of wells or piezometers needed and the units they monitor;
- frequency of water level and quality measurements, with continuous automatic recording strongly encouraged;
- action thresholds that trigger the contingency plan; and
- continued monitoring after pumping is reduced or stops, to track recovery.
The same guidance notes that daily records of water taking are required of every permit holder in all cases, and that biological and flow monitoring may be added where surface water could be affected.
Baseline private well surveys
Before dewatering or a new supply well starts pumping, a survey of neighbouring wells records what they look like under normal conditions. The Category 3 guidance asks for a reasonable effort to field-verify wells within the study area or 500 m of the pumping well, whichever is less, including at least one evening visit where no one answered during the day. Owners who refuse or cannot be reached are documented, and individuals are never named in the report.
For EASR construction dewatering, the water taking report includes a well survey, and the contingency plan must set out how affected water users will be supplied with equivalent water, or compensated, if their supply is affected.
The yearly cycle
- Site visits at the frequency the permit or plan sets: water levels, logger downloads, samples.
- Data checks during the year against action thresholds, so problems surface before the annual report.
- Daily taking volumes submitted to the ministry by March 31 for the previous calendar year.
- Annual monitoring report, where conditions require one, prepared and signed by the qualified person.
Monitoring for planning applications
Pre-development monitoring is set by the reviewing agency. The Lake Simcoe Region Conservation Authority generally expects at least 12 continuous months, including the seasonal high. Hamilton's urban guideline asks for three months of biweekly readings for mid-rise and high-rise sites and two years of continuous logging for low-rise subdivisions. See the development study page for more on these programs.
Groundwater monitoring program cost
Prices are per year. Number of wells, visit frequency and whether a formal annual report goes to a regulator drive the total.
| Answer | Indicative range |
|---|---|
| Starting point (1 to 5, Annual, No) | $4,000 – $6,500 |
| Number of monitoring wells | |
| 1 to 5 (starting point) | $4,000 – $6,500 |
| 6 to 15 | $7,000 – $11,500 |
| 16 or more | $12,000 – $19,500 |
| Monitoring frequency | |
| Annual (starting point) | $4,000 – $6,500 |
| Semi-annual | $6,000 – $10,000 |
| Quarterly | $9,500 – $15,500 |
| Regulatory annual report | |
| No (starting point) | $4,000 – $6,500 |
| Yes | $5,000 – $8,500 |
| Full span across all answers | $4,000 – $61,000 |
Each row changes one answer and leaves the others at the starting point. Indicative ranges, rounded to the nearest $500. They exclude well drilling, government application fees and HST. Final scope is confirmed by the hydrogeologist after reviewing your site.
Data loggers cut site visits but add equipment and download time. Laboratory costs rise with the parameter list. Combining monitoring for several permits on one property in a single report saves money.
What to have ready
- Your permit, registration or approval, with its conditions
- Past annual reports and the monitoring data behind them
- Locations and logs of existing monitoring wells
- The ministry account details used for reporting, if the consultant will file submissions on your behalf
Gaps reviewers flag
- Missed March 31 submission, including years with no taking.
- Data without interpretation: tables of readings with no comparison against thresholds or trends.
- Logger drift not checked against manual readings.
- Damaged or lost wells not replaced, leaving gaps in the record.
Worked annual cost examples
Each example runs the estimator's own calculation on a realistic set of answers.
-
Small permit: up to five wells, annual visit, no formal report$4,000 – $6,500
Number of monitoring wells: 1 to 5 · Monitoring frequency: Annual · Regulatory annual report: No
One round of water levels and data management, enough where the permit only needs records kept and volumes reported.
-
Six to fifteen wells, twice a year, annual report to the regulator$14,000 – $23,000
Number of monitoring wells: 6 to 15 · Monitoring frequency: Semi-annual · Regulatory annual report: Yes
Wells, frequency and the report all multiply. The formal report adds interpretation, trend analysis and comparison against permit thresholds.
-
Sixteen or more wells, quarterly, annual report$37,500 – $61,000
Number of monitoring wells: 16 or more · Monitoring frequency: Quarterly · Regulatory annual report: Yes
Typical of larger sites with long-term conditions. Data loggers can reduce visits, which a confirmed scope would reflect.
What the reviewer checks in an annual report
- Daily taking volumes complete for every day, and the March 31 submission made
- Water levels and quality compared with the permit's action thresholds
- Logger data checked against manual readings
- Laboratory quality control and chain of custody
- Trends over time, not only the current year's numbers
- Any contingency triggers reached and the response taken
- Condition of each monitoring well, and replacements where needed
- Recommendations for the next year's program
March 31 volume report or annual monitoring report?
| Aspect | March 31 water taking report | Annual monitoring report |
|---|---|---|
| Required by | O. Reg. 387/04 (permits) and the EASR rules | Conditions of the specific permit or approval |
| Content | Volume taken each day, by location | Water levels, quality, interpretation, compliance |
| Submitted through | The ministry's online reporting system | As the permit or approval directs |
| Prepared by | The permit holder or registrant | Usually the qualified person |
Where this study is commonly required
Location pages with local requirements, groundwater data and the agencies involved, by region:
Greater Toronto and Hamilton Area
Southwestern Ontario
Monitoring and reporting questions
Is the March 31 report the same as the annual monitoring report?
Not necessarily: the March 31 submission is the daily water taking volumes that every permit holder and EASR registrant must report to the ministry for the previous calendar year. Many permits add conditions for water level or quality monitoring with a separate annual report prepared by a qualified person. Check the conditions on your permit for what and when; that record also carries weight at permit renewal.
How long must monitoring records be kept?
For EASR construction dewatering, records such as daily volumes, precipitation, monitoring and complaints are kept for 5 years. For EASR pumping tests the period is 1 year. Permit conditions may set their own requirements.
What is a baseline private well survey?
A survey of nearby wells before a water taking starts: location, construction, water level and, where agreed, a water sample. It gives an objective "before" picture that helps resolve interference complaints later. The ministry's Category 3 guidance describes the survey and how much effort to make to reach owners.
Do we need data loggers, or are manual readings enough?
It depends on the purpose. The ministry's Category 3 guidance strongly encourages frequent or continuous automatic recording for production and observation wells. For planning applications, some municipalities specify the method, for example Hamilton requires continuous logging with monthly manual checks for low-rise subdivisions.
Who should own the monitoring wells?
The property owner or permit holder usually owns the monitoring wells. Wells that are no longer needed must be properly abandoned under Regulation 903, so plan for that cost at the end of the program.
Related studies
- Permit to Take Water & EASR
Work out whether a water taking needs an EASR registration or a Permit to Take Water.
- Construction Dewatering Assessment
Groundwater inflow estimates and dewatering rates for excavations, basements and servicing trenches.
- Water Supply Well Assessment & Pumping Tests
Pumping tests, well yield and interference assessments for commercial, agricultural and communal supplies.
- Hydrogeological study cost guide
Ranges for every study type, side by side.
Sources
- O. Reg. 387/04: Water Taking and Transfer (consolidated to e-Laws currency date October 9, 2026) (opens in a new tab), Government of Ontario (e-Laws).
- Permits to take water: operating your permit (opens in a new tab), Government of Ontario (MECP).
- O. Reg. 63/16: Registrations under Part II.2 of the Act - Water Taking (consolidated to e-Laws currency date October 9, 2026) (opens in a new tab), Government of Ontario (e-Laws).
- Water taking user guide for the Environmental Activity and Sector Registry (opens in a new tab), Government of Ontario (MECP).
- Technical guidance document for hydrogeological studies in support of Category 3 applications (opens in a new tab), Government of Ontario (MECP).
- R.R.O. 1990, Reg. 903: Wells (consolidated to e-Laws currency date October 12, 2026), sections 1, 1.0.2, 1.1 and 21 (opens in a new tab), Government of Ontario (e-Laws).
- Hydrogeology (planning application reviews) (opens in a new tab), Lake Simcoe Region Conservation Authority.
- Hydrogeological Study (Urban): development application guidelines (last updated February 13, 2026) (opens in a new tab), City of Hamilton.