Innisfil set out new hydrogeological requirements in late 2025. The Town and its water utility, InnServices, now publish one terms of reference that says when a hydrogeological study is needed, what it must contain, and how long it stays valid. Depending on the site, a hydrogeological study in Innisfil may be reviewed by the Town, by LSRCA or NVCA, and by the Ministry.
What this means for your project in Innisfil
- A study is needed for most planning applications where the site uses a private well or septic system, sits near wetlands or recharge areas, stores fuel or infiltrates stormwater, or has a basement close to high groundwater.
- The Town's Planning and Development Engineering staff review it, and Lake Simcoe Region or Nottawasaga Valley Conservation Authority can ask for one too, depending on the watershed.
- A study is only valid for 18 months, so time it to the application. An old report may need new monitoring data.
- The local factor most likely to affect scope and cost: shallow groundwater. The town's well records show groundwater close to the surface, which brings basements, dewatering and infiltration design into the study.
Innisfil groundwater data
Calculated from public provincial datasets for Town of Innisfil. Each value names its source; links are under Sources at the end of the page.
| Median depth of wells with a water level | 19.8 m (4,087 records reporting depth and water level) |
|---|---|
| Median static water level | 3 m below ground (4,087 records reporting depth and water level) |
| Records reaching bedrock | 4.1% of all records with a depth |
| Well records | 6,166 records (all types) |
| Active Permits to Take Water | 22 permits; largest purpose categories: Farm uses 6 (5 + 1), Water Supply 5, Construction 4 |
| Active construction and dewatering permits | 7 of 22 active Permits to Take Water |
| Conservation authority | Lake Simcoe Region Conservation Authority (56.7% of area); Nottawasaga Valley Conservation Authority (43.3% of area) |
| Provincial plan areas | Greenbelt 0.8% of area |
Source: Well Records (Water Well Information System), MECP (WWIS_2026a), retrieved 2026-10-14.
Source: Permit to Take Water, MECP (PermitsToTakeWater_26-01), retrieved 2026-10-14.
Source: Conservation Authority Administrative Area, Ontario GeoHub, retrieved 2026-10-14.
Source: Oak Ridges Moraine (ORM) Planning Area, Ontario GeoHub; Greenbelt Outer Boundary, Ontario GeoHub; Niagara Escarpment Plan Boundary, Ontario GeoHub; retrieved 2026-10-14.
Figures count records inside the municipal boundary that report a value; well locations and values are as submitted by well contractors, and MECP notes inaccuracies exist. How these figures are calculated.
Innisfil sits on deep glacial deposits rather than rock: only 4.1% of records with a depth reach bedrock. Wells that report a water level have a median water level of 3 m below ground, and their median depth is 19.8 m. 7 of the 22 active Permits to Take Water are for construction or dewatering, and water supply and agricultural takings make up most of the rest.
The December 2025 terms of reference
The Town of Innisfil and InnServices hydrogeological study terms of reference took effect on December 1, 2025. Their stated aim is to show that a development will not harm existing wells, surface water or groundwater-dependent ecosystems, and that natural recharge and discharge continue after construction.
When a study is required
- Developments relying on private wells or septic systems
- Developments near sensitive groundwater features such as aquifers, recharge areas or wetlands
- Applications involving potential contaminants, including fuel storage and stormwater infiltration
- Any proposal where groundwater interference or depletion is a concern
- Basements or floor slabs close to high groundwater levels
- Where the Town, LSRCA, NVCA or the Ministry asks for one
The requirement covers zoning by-law and official plan amendments, plans of subdivision and condominium, site plan control, CPPS by-laws, and other applications where the Town's engineering staff decide a study is needed.
What the report must contain
| Section | Key content |
|---|---|
| Proposed development | Servicing strategy, expected water use, any dewatering or infiltration features |
| Hydrogeological context | Aquifers and aquitards, recharge and discharge areas, groundwater dependency, existing wells |
| Field investigations | Monitoring wells or piezometers with continuous loggers; sampling including Provincial Water Quality Objectives parameters; slug tests or constant-rate pumping tests |
| Flow and gradient | Groundwater contour maps, flow paths and zone of influence |
| Water budget | Recharge, discharge, evapotranspiration and pre- and post-development water balance |
| Impacts | Drawdown at existing wells, baseflow to wetlands and streams, contaminant transport risk |
| Septic suitability | Soils, depth to water, percolation, nitrate plume modelling, separation distances |
| Mitigation and monitoring | Buffers, cut-off walls, recharge enhancement, pumping management |
The study must also conform to the Town's Engineering Design Standards and Specifications and follow, among other references, LSRCA's hydrogeological assessment checklist. The submission includes borehole logs, groundwater elevation data, contour maps, well records, laboratory results, raw data sheets and calibration records.
The 18-month rule
Innisfil puts a shelf life on a hydrogeological study. A study is valid for up to eighteen months from its date unless significant changes occur on site, nearby groundwater conditions change, or development work starts. For an owner, that means scheduling the study close to the application rather than years ahead, and budgeting for a monitoring update if approvals run long. The Town also reserves the right to ask for more scope during review.
Two watersheds, two conservation authorities
Lake Simcoe Region Conservation Authority covers about 56.7% of Innisfil and Nottawasaga Valley Conservation Authority about 43.3%. On the Lake Simcoe side, the Lake Simcoe Protection Plan requires a water balance for major development, and LSRCA's recharge offsetting policy can put a price on any infiltration that cannot be kept on site; our East Gwillimbury hydrogeology page explains how. The Town recommends pre-consultation with the Town, the conservation authority and the Ministry for any development in a wellhead protection or recharge area, to settle the study area and data collection before field work starts.
Questions to settle at pre-consultation
- Which of the terms of reference triggers apply, and which application types the study must support.
- Whether LSRCA or NVCA will review, and whether the site is in a wellhead protection or recharge area.
- How long the Town wants continuous logger data before submission, so monitoring starts in time.
- When the application will be filed, so the study date falls inside the 18-month validity window.
Hydrogeological study cost in Innisfil
| Study | Starting point | Full span |
|---|---|---|
| Development hydrogeological report | $12,000 – $18,000 | $12,000 – $150,000 |
| Infiltration water balance assessment | $3,000 – $5,000 | $3,000 – $14,000 |
| LID infiltration testing | $2,500 – $4,000 | $2,500 – $14,500 |
| Hydrogeology for construction dewatering | $9,000 – $14,000 | $9,000 – $62,500 |
| Hydrogeological report for a new lot | $5,500 – $8,500 | $2,500 – $17,500 |
These are indicative ranges based on typical scopes, the same province-wide ranges the estimator uses, not prices specific to Innisfil. Locally, the work is reviewed by the Town of Innisfil and InnServices, with Lake Simcoe Region or Nottawasaga Valley Conservation and, for water takings, the ministry, and the scope they ask for is what moves a quote. Shallow groundwater often brings basements, dewatering and infiltration design into the study, and the 18-month validity rule affects timing. Excludes well drilling, government application fees and HST. Read what drives hydrogeological study costs before asking for quotes.
Projects that need a hydrogeological study in Innisfil
- Subdivisions and condominiums. The full ten-section study with water budget, often with infiltration design for low impact development.
- Buildings with basements on shallow groundwater. Groundwater levels for foundation design and a dewatering assessment for construction.
- Commercial sites with fuel storage or stormwater infiltration. Named directly as triggers in the terms of reference.
- Rural development on private services. Well and septic suitability, including nitrate modelling.
Working with a hydrogeologist in Innisfil
Innisfil's terms of reference, issued with InnServices, set a validity window: a study is good for up to 18 months from its date unless conditions change or work has started, so time the field work to the application. Review can involve the Town's Planning and Development Engineering staff, Lake Simcoe Region or Nottawasaga Valley Conservation Authority depending on the watershed, and the Ministry. Groundwater is shallow in much of the town, so mention any basement at the start: the terms of reference list basements close to high groundwater among the reasons for a hydrogeological assessment in Innisfil. Check that the person signing an Innisfil study appears in PGO's register of members.
If you are dividing a rural Innisfil lot on private services, our severance study guide sets out the first questions to ask.
Innisfil questions
How long is a hydrogeological study valid in Innisfil?
Up to 18 months from its date, under the Town's terms of reference, unless conditions on or near the site change significantly or development work has started. Monitoring data may need to be reassessed, and supplementary work can be required, if site conditions, monitoring results or regulations change in that time.
My building has a basement. Does that alone trigger a study?
It can: Innisfil's terms of reference list developments with basements or floor slabs close to high groundwater levels among the cases that need a hydrogeological study, alongside private servicing, sensitive groundwater features and potential contaminants. Innisfil wells that report a water level have a median water level of 3 m below ground, so ask about groundwater at pre-consultation if you plan a basement.
Can we leave out sections of the terms of reference that do not apply?
Yes, but not silently: the terms of reference require all ten sections, and where one does not apply, the report must include a brief explanation under that heading of why not. A missing section without an explanation invites a resubmission.
Which conservation authority reviews hydrogeology in Innisfil?
Either of two conservation authorities can review hydrogeology in Innisfil, depending on the watershed. In the provincial boundary data, Lake Simcoe Region Conservation Authority covers about 56.7% of the town and Nottawasaga Valley Conservation Authority about 43.3%. The Town's terms of reference name both, and the Ministry, as bodies that can ask for a study.
What testing does the Town expect in the field?
The Town expects monitoring wells or piezometers with continuous loggers recording groundwater level changes, groundwater sampling that includes the Provincial Water Quality Objectives parameters, and slug tests or constant-rate pumping tests to work out hydraulic conductivity, transmissivity and flow direction.
Does a septic system need its own assessment?
Yes, if the development uses one: the study needs a septic suitability section covering soil conditions, depth to water, percolation, separation distances and nitrate plume modelling, in addition to the provincial D-5-4 approach for lot creation on private services.
Studies for Innisfil sites
- Development Hydrogeological Study
Groundwater assessments that support subdivision, site plan and zoning applications.
- Water Balance Assessment
Pre- and post-development water budgets for planning approvals and low impact development design.
- Infiltration Testing (LID)
In-situ infiltration testing used to size low impact development stormwater features.
- Construction Dewatering Assessment
Groundwater inflow estimates and dewatering rates for excavations, basements and servicing trenches.
- Hydrogeological study cost guide
Ranges for every study type, side by side.
Near Innisfil
Sources
- Well Records: Water Well Information System (WWIS_2026a) and county Well Record Data Reports (WW_Reports_2026a) (opens in a new tab), Government of Ontario (MECP), Ontario Data Catalogue.
- Permit to Take Water dataset (PermitsToTakeWater_26-01) (opens in a new tab), Government of Ontario (MECP), Ontario Data Catalogue.
- Conservation Authority Administrative Area (opens in a new tab), Ontario GeoHub.
- Oak Ridges Moraine (ORM) Planning Area (opens in a new tab), Ontario GeoHub.
- Greenbelt Outer Boundary (opens in a new tab), Ontario GeoHub.
- Niagara Escarpment Plan Boundary (opens in a new tab), Ontario GeoHub.
- Terms of Reference: Hydrogeological Study (effective December 1, 2025) (opens in a new tab), Town of Innisfil and InnServices Utilities Inc.
- Water Balance Recharge Offsetting Policy (May 1, 2023) (opens in a new tab), Lake Simcoe Region Conservation Authority.
- Public Register (registered members) (opens in a new tab), Professional Geoscientists Ontario.
- Municipal Boundary - Lower and Single Tier (opens in a new tab), Ontario GeoHub.
- OHN Waterbody, 2M generalized layer (provincial hydrography dataset) (opens in a new tab), Ontario GeoHub.
- Hydrogeology (planning application reviews) (opens in a new tab), Lake Simcoe Region Conservation Authority.
- D-5-4 Individual on-site sewage systems: water quality impact risk assessment (opens in a new tab), Government of Ontario (MECP).