A source water protection risk assessment looks at a proposed activity, such as fuel storage, a septic system, road salt or snow storage, inside a wellhead protection area (WHPA) and documents how it could affect a municipal drinking water well. In Ontario it supports the process run by the municipality's risk management official under the Clean Water Act, 2006, including section 59 notices and risk management plans. The assessment is completed by a licensed hydrogeologist (P.Geo.) or professional engineer (P.Eng.).
How source protection works
Ontario's source protection program has 19 source protection committees and 38 local source protection plans, which protect almost 450 municipal drinking water systems. Each plan contains local policies, implemented by municipalities, source protection authorities, health boards and the Province.
For a property owner the policies show up as restrictions. Under the Clean Water Act, 2006, where a source protection plan designates an activity and an area, section 57 prohibits the activity there and section 58 allows it only under an agreed or established risk management plan. Section 59 then stops prescribed Planning Act applications, and the construction or change of use of a building, for a designated land use in that area until the risk management official issues a notice. The official issues it only if neither section applies, or if the required risk management plan is in place.
Wellhead protection zones
The Technical Rules under the Act define four wellhead protection areas around each municipal well, based on how long groundwater takes to reach it. The Trent source protection region describes them as:
| Zone | Area |
|---|---|
| WHPA-A | 100 m radius around the wellhead; always the highest vulnerability score (10) |
| WHPA-B | Water can reach the well within 2 years |
| WHPA-C | 2 to 5 years |
| WHPA-D | 5 to 25 years |
Vulnerability scores inside each zone depend on well depth and the soil and rock above the aquifer. Whether an activity counts as a significant drinking water threat comes from the ministry's tables of drinking water threats, applied to the zone and score.
When a hydrogeological assessment helps
A hydrogeological assessment helps a source water protection case by supporting a risk management plan, testing the zone mapping, assessing transport pathways to the aquifer or showing that recharge is maintained in a water quantity zone.
- Supporting a risk management plan. Documenting site conditions, pathways and the measures that reduce the risk of a fuel tank, chemical storage or other threat activity.
- Testing the mapping. Where site data suggests the zone boundary or vulnerability at the property differs from the regional model.
- Transport pathways. Assessing whether wells, boreholes or deep excavations on the site create a new pathway to the aquifer.
- Water quantity zones. Where a plan has water quantity policies, showing that recharge is maintained; see water balance assessments.
There are knock-on effects for other permits too. The EASR registration for construction dewatering does not apply where the recommended discharge is to the natural environment inside a WHPA-A, according to the ministry's EASR water taking guide.
Process and what you receive
A source water protection risk assessment runs from confirming the zone and vulnerability score through site review to a signed assessment, after which the risk management official issues the section 59 notice.
- Confirm the zone and vulnerability score with the municipality's risk management official, often through a screening form.
- Identify which listed threat activities the proposal involves and what the source protection plan policy requires.
- Site review and, where needed, field data on soils, depth to groundwater and any transport pathways.
- A signed assessment describing the activity, the site conditions and the measures that manage the risk, for use in the risk management plan negotiation or the section 59 review.
- The risk management official issues the section 59 notice, and the planning or building application proceeds.
Timing depends mostly on the risk management official's review and, where a risk management plan is needed, on agreeing its terms. Starting the screening before the planning application is filed avoids holding up the approval.
Source water protection risk assessment cost
A source water protection risk assessment costs least for a single familiar activity, such as a septic system in an outer zone, and more for fuel storage close to the well or several activities in an unconfirmed zone.
| Answer | Indicative range |
|---|---|
| Starting point (Septic or sewage, Other WHPA) | $4,500 – $7,000 |
| Proposed activity | |
| Septic or sewage (starting point) | $4,500 – $7,000 |
| Fuel or chemical storage | $5,000 – $8,000 |
| Road salt or snow storage | $5,000 – $8,000 |
| Multiple activities | $7,500 – $12,000 |
| Wellhead protection area | |
| Other WHPA (starting point) | $4,500 – $7,000 |
| Not sure | $5,500 – $8,500 |
| WHPA-A or WHPA-B | $6,000 – $9,500 |
| Full span across all answers | $4,500 – $15,500 |
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.
Activities in WHPA-A or B, more than one threat activity, or a need to collect new field data to test the mapping push the cost up. If you are not sure which zone applies, the estimator assumes more work until it is confirmed.
Have ready
For a source water protection risk assessment, have the risk management official's screening form, a description of the activity and its quantities, a site plan and any existing environmental reports ready.
- The risk management official's screening form or correspondence
- A description of the activity: what is stored or handled, quantities and containment
- Site plan showing tanks, storage areas, drainage and any wells
- Any existing environmental reports for the property
Where applications slow down
Section 59 notices are typically tied to a specific application, so a change to the proposal can mean a new notice. Delays usually come from incomplete descriptions of the activity, missing site plans, or an assessment that does not address the specific threat listed for that zone and score.
Worked cost examples
Each example runs the estimator's own calculation on a realistic set of answers.
-
Septic system in an outer wellhead protection zone$4,500 – $7,000
Proposed activity: Septic or sewage · Wellhead protection area: Other WHPA
A single, familiar activity in a zone other than WHPA-A or B. The assessment documents the system, soils and depth to groundwater for the risk management official.
-
Fuel storage in WHPA-B$6,500 – $10,500
Proposed activity: Fuel or chemical storage · Wellhead protection area: WHPA-A or WHPA-B
Closer to the well, where more activities are significant threats. Containment, spill response and site conditions need fuller documentation.
-
Several activities, zone not yet confirmed$9,000 – $14,500
Proposed activity: Multiple activities · Wellhead protection area: Not sure
Each activity is checked against the threat tables, and confirming the zone and vulnerability score is part of the work. The estimator prices in that extra step until the zone is known.
What the risk management official checks
The risk management official checks the zone and vulnerability score, the threat circumstances and quantities, the source protection plan policy that applies, site conditions, transport pathways and the specific measures proposed.
- Zone and vulnerability score, cited from the approved assessment report
- Which listed threat circumstances the activity meets, with quantities
- The source protection plan policy that applies (prohibition, risk management plan or other)
- Site conditions: soils, depth to groundwater, drainage and nearby wells
- Any transport pathways the project creates, such as wells, boreholes or deep excavations
- The specific measures proposed and how they reduce the risk
- Consistency with the planning or building application the section 59 notice will cover
Risk assessment, risk management plan and section 59 notice
The three documents come from different hands: the property owner's hydrogeologist prepares the risk assessment, the risk management plan is agreed with or set by the risk management official, and the official issues the section 59 notice.
| Aspect | Who prepares it | What it does |
|---|---|---|
| Hydrogeological risk assessment | A qualified hydrogeologist for the property owner | Documents the activity, site conditions and risk-reducing measures |
| Risk management plan | Agreed between the person engaged in the activity and the risk management official, or established by the official | Sets the required practices; needed before a section 58 activity can take place |
| Section 59 notice | The risk management official | Lets the Planning Act or building application proceed |
Where this study is commonly required
Location pages with local requirements, groundwater data and the agencies involved, by region:
Greater Toronto and Hamilton Area
Central Ontario
Source protection questions
How do I find out whether my property is in a wellhead protection area?
Each source protection region publishes maps with its approved assessment report, and most municipalities show the zones in their online mapping. The municipality's risk management official can confirm which zone and vulnerability score apply to a specific property.
What is a section 59 notice?
A section 59 notice is the risk management official's confirmation that lets certain Planning Act and building permit applications proceed where prohibition or risk management plan policies apply. Section 59 of the Clean Water Act, 2006 restricts those approvals in areas where prohibition (section 57) or risk management plan (section 58) policies apply. The risk management official issues a notice confirming either that no prohibited activity or risk management plan is involved, or that the required plan is in place, before the application can proceed.
Can an activity be prohibited outright?
An activity can be prohibited outright, but only if it is a future activity that would be a significant drinking water threat where the source protection plan says so. The Trent source protection region's example is a gas station proposed in a WHPA-A, which would be prohibited. Prohibition applies only to future activities; existing ones are usually managed with risk management plans.
Who writes the risk management plan?
The risk management plan is negotiated between the person engaged in the activity and the risk management official, and sets out the best management practices required. A hydrogeological assessment can support the negotiation, for example by documenting site conditions or showing how a measure reduces the risk.
Does this apply to private wells?
Not directly: source protection plans protect municipal residential drinking water systems. Private wells are not mapped this way, although a property near a private well may still need a hydrogeological assessment for other reasons, such as a septic system under D-5-4.
How does a source water protection risk assessment differ from a risk management plan?
A source water protection risk assessment is prepared by a qualified hydrogeologist for the property owner and documents the activity, site conditions and risk-reducing measures. A risk management plan is agreed between the person engaged in the activity and the risk management official, or established by the official, and sets the required practices; a section 59 notice then lets the Planning Act or building application proceed.
Related studies
- Water Balance Assessment
Pre- and post-development water budgets for planning approvals and low impact development design.
- Hydrogeological Assessment for Large Septic Systems
Groundwater impact assessments for larger on-site sewage systems.
- 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
- Source protection (opens in a new tab), Government of Ontario (MECP).
- Clean Water Act, 2006, sections 57 to 59 (opens in a new tab), Government of Ontario (e-Laws).
- What is a wellhead protection area? (fact sheet) (opens in a new tab), Trent Conservation Coalition Source Protection Region.
- Tables of drinking water threats (opens in a new tab), Government of Ontario (MECP).
- Water taking user guide for the Environmental Activity and Sector Registry (opens in a new tab), Government of Ontario (MECP).