A hydrogeological study in Caledon has to deal with more overlapping layers than almost anywhere else in the Greater Toronto Area: provincial plans over most of the town, two main conservation authorities, municipal wells run by the Region of Peel, and large rural areas on private wells and septic systems. Depending on the site, the Town, the Region and a conservation authority may all review the same report.
What this means for your project in Caledon
- Most Caledon studies support one of three things: subdivisions and site plans in the settlement areas, rural and estate lots on a private well and septic system, or activities close to the Region of Peel's municipal wells.
- Expect up to three reviewers: the Town of Caledon, the Region of Peel and a conservation authority, either Toronto and Region or Credit Valley depending on the watershed.
- Most of Caledon is in the Greenbelt, and parts are on the Oak Ridges Moraine or in the Niagara Escarpment Plan area. These plans can add a hydrological evaluation or a water budget.
- The local factor most likely to affect scope and cost: whether the property is on the Oak Ridges Moraine or inside a wellhead protection area. Either can add monitoring and reporting, so check both before you ask for quotes.
The layers on a Caledon property
The provincial boundary data in the panel below puts 80.2% of Caledon's area inside the Greenbelt outer boundary, 23.2% on the Oak Ridges Moraine and 19.6% in the Niagara Escarpment Plan area. Each brings its own rules, and a single property can sit under more than one.
- Oak Ridges Moraine. Section 26 of the Oak Ridges Moraine Conservation Plan requires a hydrological evaluation for development or site alteration within the minimum area of influence of a key hydrologic feature, and section 24 requires a water budget and water conservation plan for some major development.
- Wellhead protection areas. Activities near the Region's municipal wells are managed under the source protection plans (below).
- Conservation authority watersheds. Toronto and Region Conservation Authority (53.2%), Credit Valley Conservation (44.6%), Nottawasaga Valley Conservation Authority (1.5%).
- Private servicing. Rural lots on wells and septic systems bring in the provincial D-5-4 and D-5-5 guidelines.
Caledon groundwater data
Calculated from public provincial datasets for Town of Caledon. Each value names its source; links are under Sources at the end of the page.
| Median depth of wells with a water level | 26.2 m (6,653 records reporting depth and water level) |
|---|---|
| Median static water level | 7.9 m below ground (6,653 records reporting depth and water level) |
| Records reaching bedrock | 33.4% of all records with a depth |
| Well records | 11,514 records (all types) |
| Active Permits to Take Water | 30 permits; largest purpose categories: Commercial 9, Water Supply 5, Construction 3 |
| Active construction and dewatering permits | 3 of 30 active Permits to Take Water |
| Conservation authority | Toronto and Region Conservation Authority (53.2% of area); Credit Valley Conservation (44.6% of area); Nottawasaga Valley Conservation Authority (1.5% of area) |
| Provincial plan areas | Oak Ridges Moraine 23.2%; Greenbelt 80.2%; Niagara Escarpment Plan 19.6% 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.
Compared with Toronto, Caledon's records look like a rural water-well area. 33.4% of records with a depth reach bedrock. Among the 6,653 wells that report both a depth and a water level, the median depth is 26.2 m and the median water level is 7.9 m below ground. The 30 active Permits to Take Water include commercial, water supply, agricultural and construction takings.
Municipal wells and wellhead protection
The Region of Peel's private wells page states that municipal well-based systems or privately owned wells provide water to rural parts of Caledon. The Region's wells operate under its own Permits to Take Water with ongoing monitoring: the 2025 Caledon Village report, for example, covers three production wells (Caledon Village Wells 3, 3B and 4) under the Region's groundwater and surface water monitoring program.
Around each municipal well are wellhead protection areas. Peel's notice for the Palgrave Well #4 capacity increase describes them: WHPA-A, a 100 m fixed radius around the wellhead, then WHPA-B, C and D at 2-, 5- and 25-year groundwater travel times, delineated by hydrogeological modelling under the Clean Water Act. Because the proposed increase in water taking at Palgrave Well #4 for the Palgrave-Caledon East system enlarges those zones, more properties fall inside them, and activities such as septic systems, heating oil tanks, agricultural uses and chemical storage may need field verification to see whether source protection plan policies apply. Depending on the source protection area, the CTC Source Protection Plan or the South Georgian Bay Lake Simcoe Source Protection Plan governs.
The Region's official plan review material, Peel 2051, proposed regulating development and site alteration in vulnerable areas and requiring studies to assess whether development could threaten municipal drinking water sources. For a proposal near a well, that means the hydrogeological work and the source protection screening belong in the same early conversation.
Where new serviced development sits near homes on private wells, the Region's hydrogeologic assessment guidelines for new developments (revised July 2009) ask the developer to monitor every well in the zone of influence before, during and for one year after construction. A baseline report with water levels, bacteria and nitrate results goes to the Region before pre-servicing or registration, with a contingency plan for replacing any supply that is affected.
What the Caledon Village wellfield shows
The Region's monitoring reports give a rare public look at Caledon's aquifers. According to the 2025 Caledon Village report, the wells sit in a glacial spillway known locally as the Caledon Meltwater Channel. Wells 3 and 3B are understood to be completed in an unconfined sand and gravel aquifer, while Well 4 draws from a confined to semi-confined aquifer, and Wells 3 and 4 have been assessed as groundwater under the direct influence of surface water, with effective filtration.
The same report records how the system responds to weather: from July to September 2025 less than half the seasonal precipitation fell across southwestern Ontario, and while monitoring wells stayed within their expected range, some shallow drive-point piezometers responded to the drought. For a study on nearby land, those are the points that matter: an unconfined aquifer connected to surface water, close to a municipal supply, with shallow water levels that react to dry summers. Monitoring that captures seasonal change, and an impact assessment that considers the wellfield, follow directly.
Hydrogeological study cost in Caledon
| Study | Starting point | Full span |
|---|---|---|
| Development hydrogeology report | $12,000 – $18,000 | $12,000 – $150,000 |
| Severance study (D-5-4 / D-5-5) | $5,500 – $8,500 | $2,500 – $17,500 |
| Water balance study | $3,000 – $5,000 | $3,000 – $14,000 |
| Source protection risk assessment | $4,500 – $7,000 | $4,500 – $15,500 |
| Pumping test and well assessment | $7,000 – $11,000 | $7,000 – $86,500 |
These are indicative ranges based on typical scopes, the same province-wide ranges the estimator uses, not prices specific to Caledon. Locally, the work is reviewed by the Town of Caledon, the Region of Peel and Toronto and Region or Credit Valley Conservation and, for water takings, the ministry, and the scope they ask for is what moves a quote. Wellhead protection areas and Oak Ridges Moraine or Greenbelt policies can add source protection screening or water budget work. Excludes well drilling, government application fees and HST. For worked examples, see what a hydrogeological study costs in Ontario.
Projects that need a hydrogeological study in Caledon
- Subdivisions and site plans in settlement areas. A development hydrogeological study, often with a water balance where provincial plan or recharge policies apply.
- Estate and rural residential lots. D-5-4 nitrate assessment and D-5-5 well testing, with attention to neighbouring private wells downgradient.
- Development on the Oak Ridges Moraine. A hydrological evaluation near key hydrologic features, and a water budget for some major development.
- Businesses and farms inside a wellhead protection area. A source water protection assessment to support the Region's review of fuel, chemical or septic activities.
- New commercial or agricultural water supplies. Pumping tests and, above 50,000 L/day, a Permit to Take Water.
A sensible order of work
- Confirm which plan areas, watershed and wellhead protection zones the property is in.
- Ask the Town, the Region and the conservation authority what studies they expect, ideally together.
- Start groundwater monitoring early: the agencies want seasonal data, and monitoring is usually the longest part of the schedule.
- Combine the hydrogeological study, water balance and any hydrological evaluation into one field program where possible.
Working with a hydrogeologist in Caledon
In Caledon the same report may be read by the Town, the Region of Peel and Toronto and Region or Credit Valley Conservation, depending on where the site drains, and Peel's municipal wells bring source protection screening to the communities they supply. Send the consultant the property location first so wellhead protection zones and the Oak Ridges Moraine and Greenbelt boundaries can be checked; those decide whether a hydrological evaluation or a water budget is needed. Rural lots on private wells and septic systems are scoped as a hydrogeological assessment in Caledon under the D-5-4 and D-5-5 guidelines. For a Caledon rural lot, check that the person signing the well and septic assessment is listed in the PGO member search.
For a Caledon lot split, start with our severance hydrogeology guide, which explains where D-5-4 and D-5-5 testing comes in.
Caledon questions
How do I know whether my Caledon property is in a wellhead protection area?
Ask the Region of Peel. The Region notifies owners when wellhead protection areas change: its Palgrave notice told owners their property fell inside the proposed updated zones whether or not they use municipal water. The Town's zoning maps also show wellhead protection areas.
My land is on the Oak Ridges Moraine. What extra study is needed?
Under section 26 of the Oak Ridges Moraine Conservation Plan (O. Reg. 140/02), an application for development or site alteration within the minimum area of influence of a key hydrologic feature must include a hydrological evaluation, with an exception for certain agricultural buildings at least 30 m from the feature. Some major development applications also need a water budget and water conservation plan under section 24.
Which conservation authority will review my study?
The watershed decides which conservation authority reviews a Caledon study. In the provincial boundary data, Toronto and Region Conservation Authority covers about 53.2% of Caledon and Credit Valley Conservation about 44.6%, with a small area under Nottawasaga Valley. Your property's location decides which one comments.
Does the Region or the Town run the water supply?
The Region of Peel operates the municipal wells. Peel's private wells page states that municipal well-based systems or privately owned wells supply rural parts of Caledon, and its Caledon Village wells, for example, operate under a Region of Peel Permit to Take Water with an annual monitoring report.
I am creating estate lots on private wells and septic systems. What applies?
The provincial D-5-4 and D-5-5 guidelines set the method: nitrate impact at the property boundary for the septic systems, and pumping tests and water quality for the wells. In a wellhead protection area, a septic system can also be a drinking water threat activity under the source protection plan, so check that first.
Why would a property owner without municipal water be affected by source protection?
Because wellhead protection areas are drawn around where groundwater flows to the municipal well, not around who is connected. Peel's Palgrave notice lists septic systems, home heating oil tanks, agricultural land uses and chemical storage as activities that may need field verification once the zones are updated.
Studies for Caledon properties
- Development Hydrogeological Study
Groundwater assessments that support subdivision, site plan and zoning applications.
- Source Water Protection Risk Assessment
Assessments for activities proposed inside wellhead protection areas and other vulnerable areas.
- Water Balance Assessment
Pre- and post-development water budgets for planning approvals and low impact development design.
- Severance Hydrogeological Study (D-5-4 / D-5-5)
Groundwater quality and well supply assessments for rural lot creation under MECP guidelines D-5-4 and D-5-5.
- Hydrogeological study cost guide
Ranges for every study type, side by side.
Near Caledon
Sources
- O. Reg. 140/02: Oak Ridges Moraine Conservation Plan (opens in a new tab), Government of Ontario (e-Laws).
- 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.
- Private wells: well construction and protection (opens in a new tab), Region of Peel.
- 2025 Caledon Village annual water level and water quality report (PTTW monitoring program) (opens in a new tab), Region of Peel.
- Notice of proposed wellhead protection area update: supply capacity increase for Palgrave Well #4 (opens in a new tab), Region of Peel.
- Peel 2051: water resources (official plan review) (opens in a new tab), Region of Peel.
- Guidelines for Hydrogeologic Assessment and Reporting Requirements, New Developments on Municipal Services (revised July 2009), Public Works Design, Specifications and Procedures Manual (opens in a new tab), Region of Peel.
- 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.
- D-5-4 Individual on-site sewage systems: water quality impact risk assessment (opens in a new tab), Government of Ontario (MECP).
- D-5-5 Private wells: water supply assessment (opens in a new tab), Government of Ontario (MECP).