How Long Does a Hydrogeological Study Take?
The published minimums and notice periods that set the schedule, and how to keep them off the critical path.
How long a hydrogeological study takes depends far less on writing the report than on three clocks the consultant does not control: how long the reviewer wants groundwater monitored, how long the field tests have to run, and how far ahead approvals and notices have to be in place. No agency publishes a standard duration for a whole study, but most of those clocks are written down, and they are set out below with their sources.
The longest clock: monitoring
For any study that has to establish the seasonal high water table, the monitoring period is the critical path. Published minimums vary widely:
| Who | Monitoring expected |
|---|---|
| Lake Simcoe Region Conservation Authority (LSRCA) | Generally at least 12 continuous months to support a planning application, including the seasonal high |
| York Region terms of reference | Four-season monitoring, including seasonally and historically high levels |
| Hamilton (City urban hydrogeological study guidelines) | Three months of biweekly readings for mid- and high-rise sites, longer where highly porous deposits are found; two years of continuous logging for low-rise subdivisions before detailed design |
| Mississauga (terms of reference) | At least three monthly measurements over at least three months |
| Brampton (terms of reference) | At least three months of water level monitoring |
The same project can therefore need three months in one municipality and a year in the next. The local terms of reference decide it, so read them before the wells go in.
Tests with fixed lengths
- Private well test for a severance. Guideline D-5-5 calls for at least six hours of continuous pumping, then recovery monitoring until 95% recovery or 24 hours, whichever is less, followed by laboratory analysis of the samples.
- Pumping tests registered on the EASR. Under water taking EASR regulation (O. Reg. 63/16), a pumping test can be registered rather than permitted when it takes more than 50,000 and not more than 5,000,000 litres a day over seven or fewer days within a 30-day period.
- Hydraulic response tests. Single-well tests in monitoring wells take hours, not days, but they need wells that are installed, developed and stable first.
Approvals and notices to book ahead
| Step | Published notice or review time |
|---|---|
| EASR dewatering: notice before pumping | Written notice to affected water users and the ministry district office at least 48 hours before the first taking (water taking EASR regulation (O. Reg. 63/16)) |
| Toronto sewer discharge | Applications at least eight to 12 weeks before discharge (City of Toronto) |
| York Region discharge, primary municipalities | Up to six weeks to review a complete package (York Region) |
| Permit to Take Water | Minimum 30-day Environmental Registry comment period where posting is required; no fixed review time (MECP guidance on permits to take water) |
| Permit to Take Water renewal | Apply six months before the expiry date (MECP guidance on operating your permit) |
For a construction project these run in parallel with the study, not after it. The step-by-step guide to dewatering under the EASR shows where each falls.
How long a finished study stays usable
Timing matters at the other end too. Innisfil's terms of reference treat a study as valid for up to 18 months from its date, unless site conditions change or development has started; after that, monitoring data may have to be reassessed. A study finished long before the application is filed can cost a second round of work, so time the report to the application. Our Innisfil page covers that rule.
Keeping the study off the critical path
- Read the terms of reference first. The monitoring minimum is the single biggest factor, and it is known before any drilling.
- Install wells with the geotechnical drilling. One mobilization, and the monitoring clock starts as early as possible. See hydrogeological study vs geotechnical report.
- Catch the spring. Wells installed in late winter capture the seasonal high in the first months of monitoring; wells installed in summer may have to wait most of a year for it.
- Start permits in parallel. Sewer discharge applications and, where needed, a Permit to Take Water have their own notice and review times; they can begin once the dewatering estimate is reliable.
- Answer review comments with data, not argument. A resubmission that adds the missing readings or tests moves faster than one that explains why they were not needed.
For Toronto sites, where construction dewatering and sewer discharge approvals usually run together, the local page sets out the City's rules. The development hydrogeological study page covers scope and cost.
Related questions
Can a hydrogeological study be done in a few weeks?
Some can: work that relies on existing information, such as a water balance built from soils, land cover and climate data, is mostly desk work. A study that needs new monitoring wells and a seasonal record cannot be shortened below the monitoring period the reviewer expects, however quickly the report is written.
Why do reviewers care so much about spring water levels?
Because the seasonal high, usually in spring, decides basement and foundation design, how deep infiltration features can go and how much dewatering a project needs. A record that misses the spring has to estimate it, and reviewers look hard at that estimate.
Does the ministry publish a review time for a Permit to Take Water?
No: the ministry's permit guidance describes the steps, including a minimum 30-day comment period on the Environmental Registry where posting is required, but there is no fixed decision time. Plan the field work and application well ahead of when water is needed.
Where to go next
- Development Hydrogeological Study: scope, cost and what the reviewer checks
- Hydrogeological study Innisfil: local rules, data and costs
- Hydrogeological study Hamilton: local rules, data and costs
- Hydrogeological study Toronto: local rules, data and costs
- Hydrogeological study vs geotechnical report
- What’s in a hydrogeological report
Sources
- Hydrogeology (planning application reviews) (opens in a new tab), Lake Simcoe Region Conservation Authority.
- Terms of Reference: Hydrogeological Report (Development Application Supporting Studies, June 2024) (opens in a new tab), York Region.
- Hydrogeological Study (Urban): development application guidelines (last updated February 13, 2026) (opens in a new tab), City of Hamilton.
- Terms of Reference: Hydrogeological Report (July 2023) (opens in a new tab), City of Mississauga, Transportation and Works.
- Terms of Reference: Hydrogeological Report (June 2025) (opens in a new tab), City of Brampton.
- D-5-5 Private wells: water supply assessment (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).
- Discharge permits and agreements for private water (opens in a new tab), City of Toronto.
- Sewer Use Permits: Temporary Dewatering Discharge Program (Sewer Use Bylaw No. 2021-102) (opens in a new tab), York Region.
- Permits to take water (opens in a new tab), Government of Ontario (MECP).
- Permits to take water: operating your permit (opens in a new tab), Government of Ontario (MECP).
- Terms of Reference: Hydrogeological Study (effective December 1, 2025) (opens in a new tab), Town of Innisfil and InnServices Utilities Inc.