Source Assessment & Protection Planning


When planning and managing your small water system, you will have to understand that water sources serve multiple sectors–such as tourism, resource extraction and agriculture–that British Columbia relies on economically. Each in its unique way puts pressures on the water's quality and quantity. And as our population grows, so does the pressure placed on our watersheds and aquifers.

Taking these multiple interests and demands into consideration, most water professional recognize the importance of source protection planning, based on source assessments, to be one of the most important tools in maintaining a sustainable water source and drinking water quality.

Glossary of Terms
source water

Source water is the raw, untreated ground water and surface water that supplies your water intake or well.


An observed biological (e.g., pathogens), chemical (e.g., dissolved metals, nutrients) or physical agent (e.g., turbidity, debris) that could harm your water users or water system.


Risk, for the purposes of source assessments, is a factor generally defined as the probability (likelihood) that harm, injury or loss will occur to people or infrastructure, multiplied by the magnitude (consequence) of those hazards occuring


The underground layer of water-soaked sand and rock that acts as a water source for a well; described as artesian (confined) or water table (unconfined).


Microscopic living organisms that usually consist of a single cell. Most bacteria use organic matter for their food and produce waste products as a result of their life processes.

distribution system

The equipment involved with the delivery of treated water from the treatment facility to the intended end-point user.

ground water

The supply of fresh water found beneath the Earth's surface (usually in aquifers) that is often used for supplying wells and is a source of springs.


A force acting on a given area. The pressure is calculated by dividing the force by the area over which it is acting. The unit of pressure is the Pascal (metric system) or pound per square inch (psi).

raw water

Water in its natural state, prior to any treatment. Usually the water entering the first treatment process of a water treatment plant.


A pond, lake, basin, or other structure (natural or artificial) that stores, regulates, or controls water.

surface water

All water naturally open to the atmosphere (rivers, lakes, reservoirs, streams, impoundments, seas, estuaries, etc.); also refers to springs, wells, or other collectors that are directly influenced by surface water.


The cloudy appearance of water caused by the presence of suspended and colloidal matter. In the waterworks field, a turbidity measurement is used to indicate the clarity of water. Technically, turbidity is an optical property of the water based on the amount of light reflected by suspended particles.


A watershed is an area of land that catches rain and snow and drains or seeps into a marsh, stream, river, lake or groundwater. Homes, farms, cottages, forests, small towns, big cities and more can make up watersheds. Some cross municipal, provincial and even international boarders. They come in all shapes and sizes and can vary from millions of acres, like the land that drains into the Great lakes, to a few acres that drain into a pond.


Importance Of Understanding Your Water Source

Natural events and human activities in watersheds affect the quality and quantity of the water we receive at our water system intakes and at our homes.

If the source water quality is poor, we often need to use additional and more complex water treatment. Sometimes disturbances in our watersheds require water suppliers to seek new or more dependable water sources, which can be time consuming and expensive. Poor water quality can lead to customer complaints, an increased risk of illness and a greater chance of liability.

Water quantity can also be problematic for water suppliers. In times of freshet, water quality can be negatively impacted and adjustment to the treatment process may be required. Too little water can lead to water shortages and customer complaints. In times of water shortage, water conservation should be a priority. According to the Water Sustainability Act, all water supply wells in BC, including wells in First Nations communities, must be registered and licensed. This gives you first priority to draw water.

Understanding, Assessing and Protecting Your Water Source

Source Assessments and Source Protection Plans together help you understand your water source, document the observed hazards and manage the risks associated with natural and human-made hazards. It is also the first step in protecting your water source.

Developing a source assessment requires more than a one-time assessment. The water source should be reassessed periodically to determine if new hazards exist or if already identified hazards are getting worse or better.


  • Source water is the raw, untreated ground water and surface water that supplies your water intake or well.

  • A hazard or a contaminant is an observed biological (e.g., pathogens), chemical (e.g., dissolved metals, nutrients) or physical agent (e.g., turbidity, debris) that could adversely effect consumers or the water system.

  • Risk, for the purposes of source assessments, is a factor generally defined as the probability (likelihood) that harm, injury or loss will occur to people or infrastructure, multiplied by the magnitude (consequence) of those hazards occuring.

In any source assessment, some hazards have greater risks than others, depending on the factors involved.

Determining the Catchment Area (Surface Source) & Capture Zone (Ground Water)

Determining your water assessment area is the first step in understanding your water source. The method you use to identify your assessment area will depend on your water source, which might be a well or spring, lake or reservoir, or river or stream.

A helpful resource to understand your surface and ground water sources and your options for assessing them is the Source Assessment Report section of the British Columbia Small Water Systems Source Protection Plan Toolkit

Additional information:

This toolkit works well in conjunction with Module 1 of the Comprehensive Drinking Water Source-to-Tap Assessment Guideline.

More information is also available at Design Guidelines for Rural Residential Community Water SystemsChapter 2: "Source of Supply". 

Hazards and Risks

Once you have determined an assessment area, walk the land and/or use your local knowledge of the area to identify hazards that could potentially add bacteria, chemicals or physical objects to your water source. Map and record them on a Hazard Inventory, such as the ones at Tables 2.2 and 2.3 of Module 2 of the Comprehensive Drinking Water Source-to-Tap Assessment Guideline.

Remember, though, that not all hazards are significant. The significance of a hazard is called risk, which could range from low risk to high risk. 

Having identified the hazards, you now prioritize them using a risk analysis matrix. This stage uses Module 7 from the Comprehensive Drinking Water Source-to-Tap Assessment Guideline as a reference. It includes guidelines and tables to help you determine the risk of each of your hazards.

The risk is determined by analyzing the impact or consequence a drinking water hazard would have if it does occur. Consider what the nature and potential impact of the consequences would be:

  • Unacceptable water quality at point of intake, after treatment, anywhere in the distribution system or point of use?
  • Potential for acute or long‐term health impacts for water consumers?
  • Loss of or significant reduction in source water volume or source capacity?
Source Protection Planning

Having identified the highest priority hazards in your watershed based on the risks they pose, you can now develop a source protection plan on how to address those hazards. The risk management plans do not have to be complicated, but be sure to document your efforts as you take steps to address hazards near you water source. For reference, use Module 8 of the Comprehensive Drinking Water Source-to-Tap Assessment Guideline.

Also, remember that not everything in your watershed or aquifer is within your control. Understanding who to contact to help address your hazards is an important part of any plan. Contact your local Environmental Health Officer or Drinking Water Officer (DWO) of your regional Health Authority if you need help with your plan.

In the end, the water system provider, in consultation with the DWO, is responsible for the implementation of the management actions. An implementation strategy will help ensure the management activities are taken. In the strategy, assign roles and responsibilities, develop an implementation schedule and a monitoring program to measure progress, and allocate resources.

As said earlier, a source assessment is not a one-time activity. It needs to be reviewed and updated as changes to the water system and environment occur. At least once every 5 years, conduct a full plan review and update the assessment report as needed.

Preparing a Source Assessment and Protection Plan
Reporting Complaints