A source protection plan protects the area around municipal wells and surface water intakes. These are called vulnerable areas.
Most communities in the Lake Erie Source Protection Region get their water from wells. Wells draw water from underground areas called aquifers where water fills cracks in bedrock or spaces between grains of sand, gravel or dirt.
Water moves vertically from the surface, down through the ground, to the aquifer. It also moves horizontally through the aquifer toward the well.
How fast it moves depends on the geology. Water moves quickly through sandy soil and slowly through clay or fractured bedrock.
Scientists studied every municipal well to learn how easily water (and pollutants) can travel from the surface to the aquifer and then through the aquifer to the well.
They examined two factors:
The scientists used the information to draw lines on maps called Wellhead Protection Areas:
The areas of greatest concern for source protection planning are the areas closest to the well: the 100-metre, 2-year and 5-year zones with a high vulnerability score (i.e. eight or 10).
Some communities get some or all of their water from rivers and streams. Pollutants spilled into a waterway or running off from nearby land can reach an intake within hours.
The operators of the municipal water intake can close the intake until the spill passes by. But they need enough warning time to close the intake. If a spill takes place close to the intake, there may not be enough time to close the gate. Therefore, it is important to reduce the number of threats to water in the areas close to the intake.
Scientists measured how quickly water moves in the rivers and streams. They used that information to draw lines called Intake Protection Zones (IPZ). The zones were assigned vulnerability scores on a 10-point scale:
Some communities have intakes in Lake Erie. Usually they are a fair distance offshore and on the lake floor. This makes them less vulnerable to pollutants.
Scientists studied how water moves in the lake by taking into account currents, wind patterns, the proximity of rivers and stream outlets and other factors.
They used the information to draw Intake Protection Zones around the intakes and assign vulnerability scores: