Sean Ledgerwood

The Environment Department will probe an apparent increase in pesticide detections in groundwater, says Sean Ledgerwood, watershed and subdivision specialist. (CBC)

An increase in pesticides detected through a 10-year groundwater monitoring program is receiving a closer look by P.E.I.'s Environment Department.

Government has been testing the same 100 wells each year for a decade. The locations include private and municipal wells, schools and seniors' homes.

Each site is tested for more than 30 pesticides.

Almost half of the wells tested across the Island have some trace amounts of one or more pesticide, says Sean Ledgerwood, watershed and subdivision specialist with the department.

Ledgerwood says in the past couple of years, there appears to be an increase in the number of samples that show pesticide detections.

New laboratory equipment introduced last year renders the tests more sensitive to the presence of pesticides. Therefore, the total number of detections in samples increased from 21 in 2012 to 73 the following year and jumped again in 2014 to 85. That's out of more than 2,500 samples.

However, records indicate that samples with detections increased anyway using the lower, pre-2013 laboratory limits — 40 detections in 2013 and 53 in 2014.

"We want to sit down and do some mathematical stuff with it, and make sure that, is there a trend or is there not? So I can't say if there is or not right now … It does appear that it's going up a little bit, and what we want to do because of looking at that is confirm whether that's a significant increase or not."

None of the samples has ever shown detection levels above drinking water guidelines, says Ledgerwood.              

The province won't say exactly where the wells are located.