Most score top marks Pesticide residue and fecal coliforms were found in five irrigation districts
LETHBRIDGE — Water in Alberta’s irrigation canals is getting top grades.
The province has been testing water in the province’s 13 irrigation districts since 2011, and with a few exceptions the results have been good, said Jollin Charest of Alberta Agriculture’s irrigation branch.
The most recent results produced an average score of 91.3 out of 100 for irrigation.
Five sites did not have excellent or good water quality, largely because of pesticides and fecal coliforms.
Clean water for livestock, aquatic life and food production is essential, but quality tends to degrade in some places as agricultural activity in-creases, Charest told an irrigation conference in Lethbridge Jan. 22.
Southern Alberta’s irrigation system delivers water for agriculture as well as about 40 municipalities, wildlife habitat and recreation on the reservoirs. Sixty percent of fed cattle are finished in irrigation regions.
Samples are tested four times during the irrigation season, starting in May and continuing throughout high demand periods. Fields are tested to measure nitrogen and phosphorus levels, salts, metals, pathogens and pesticides to determine if water is safe for a specific use, such as livestock, irrigation and recreation.
Charest said nutrients are present in the water supply.
“Phosphorus and nitrogen are essential for plant growth, but if they are too high they contribute to algae growth,” he said.
Their presence may also contribute to eutrophication, which depletes water oxygen and kills fish.
Salinity is naturally present and includes sodium, potassium, calcium, chloride and sulfates.
“These can be problematic if they are in high concentration as they can interfere with root water uptake,” he said. Samples show salt concentrations are still within guidelines.
Staff tested for 25 metal compounds, including arsenic, lead, copper, iron, mercury, zinc and aluminum. Compliance was 98 percent under irrigation and livestock guidelines.
Testing has found small traces of E. coli O157:H7, salmonella and campylobacter. Guidelines differ for irrigation and recreation.
Testing also looked for 107 pesticides. Among herbicides, 2,4-D was detected 85 percent of the time but at extremely low levels.