Oldman River Basin Water Quality Initiative

The Urban Beneficial Management Practices Team of the Oldman River Basin Water Quality Initiative helped oversee a study of water quality in the City of Lethbridge storm drains.

The study was designed to assess the quality of runoff entering the Oldman River via the City of Lethbridge's storm drainage system. Eight storm drains (outfalls) were selected to represent different areas and land-uses within the city.

The original intent of the study was to sample storm water runoff, however, because the summer of 2000 was fairly dry, there was only one opportunity to sample a storm event (end of August). Therefore, samples taken in June, July, early August and September represent runoff from human activities such as lawn watering and car washing rather than from precipitation.

Pesticides in Storm Drains - Preliminary Findings

13 different pesticides were detected. Herbicides: 2,4-D; dichlorprop, atrazine, bromacil, bromoxynil, dicamba, MCPA, MCPP, picloram. Insecticides: diazinon, lindane, dimethoate, malathion.
The month with the greatest number of different compounds (14) detected was June.
Between 6 to 10 different compounds were found at each site. Sites with the greatest number of pesticides detected (10) were outfalls 4 and 7.
Maximum concentrations for five of the pesticides detected in storm drains occurred in June, while the maximum concentrations for seven others occurred during the August storm event. For one compound, the maximum concentration occurred in July.
The highest concentration measured was 60.5 mg/L for MCPP during the August storm event in outfall 6. No guideline has been set for this compound. The second highest, measured in the same sample, was 46.9 mg/L for 2,4-D. This is more than ten times the guideline for the protection of aquatic life of 4 mg/L.
The three most commonly detected compounds in the storm drain samples were 2,4-D (92% of 39 samples), MCPP (mecoprop) (85%), and dicamba (82%).
Eleven of the 13 compounds detected have established guidelines. The compounds that did not meet irrigation guidelines were dicamba (31 times), MCPA (12) and bromoxynil (1). Those not meeting guidelines for the protection of aquatic life were MCPA (1), lindane (3), 2,4-D (2), atrazine (1) and malathion (1).

Further Information Required

This data will be placed in context of land use in each drainage area, as well as in terms of flow and volume, in order to assess the impact of the pesticide load contributed to the Oldman River from the urban drainage system.

What Do These Findings Mean?

This is only preliminary data, but the information so far indicates that we are finding pesticides in storm drains emptying directly into the Oldman River.

What Can I Do to Help?

All urban residents are encouraged to handle and use pesticides responsibly. This means using them according to the instructions on the label, not pouring "grey"/contaminated/polluted water and/or chemicals down the storm drain, and not over watering lawns and sidewalks.

Watch what you throw down the sink and street drains!
Pesticides and herbicides can kill beneficial bacteria in the sewage treatment plant. These materials should be disposed of through your local toxic round-up program.
Limit the amount of chemicals you use on your lawn. Once applied in excess, they persist in the turf and soil. When water is applied they are carried with the runoff into the storm system and ultimately to the Oldman River.
Do not water excessively. Once lawn watering has saturated the soil and turf, the remainder of the water that is applied becomes surface runoff. This runoff ultimately finds its way onto the streets and into the storm water system, carrying whatever pollutants it picks up on the way.
Do not dump anything into catch basins or manholes. The City of Lethbridge holds Residential Toxic Roundups once a month, at which time residents may bring household hazardous wastes for proper disposal. For more information, call the City of Lethbridge at (403) 329-7367.
If you notice a problem, report it immediately to the City at (403) 320-3850 or Alberta Environment at 1-800-222-6514, so that a proper clean up can occur.

Check out the following web sites for information on water, water quality and waste:




		Storm Drains Quality of Water from City of Lethbridge Storm Drains Summer 2000 - Pesticides Urban Beneficial Management Practices Team Background The Urban Beneficial Management Practices Team of the Oldman River Basin Water Quality Initiative helped oversee a study of water quality in the City of Lethbridge storm drains. The study was designed to assess the quality of runoff entering the Oldman River via the City of Lethbridge's storm drainage system. Eight storm drains (outfalls) were selected to represent different areas and land-uses within the city. The original intent of the study was to sample storm water runoff, however, because the summer of 2000 was fairly dry, there was only one opportunity to sample a storm event (end of August). Therefore, samples taken in June, July, early August and September represent runoff from human activities such as lawn watering and car washing rather than from precipitation. Pesticides in Storm Drains - Preliminary Findings 13 different pesticides were detected. Herbicides: 2,4-D; dichlorprop, atrazine, bromacil, bromoxynil, dicamba, MCPA, MCPP, picloram. Insecticides: diazinon, lindane, dimethoate, malathion. The month with the greatest number of different compounds (14) detected was June. Between 6 to 10 different compounds were found at each site. Sites with the greatest number of pesticides detected (10) were outfalls 4 and 7. Maximum concentrations for five of the pesticides detected in storm drains occurred in June, while the maximum concentrations for seven others occurred during the August storm event. For one compound, the maximum concentration occurred in July. The highest concentration measured was 60.5 mg/L for MCPP during the August storm event in outfall 6. No guideline has been set for this compound. The second highest, measured in the same sample, was 46.9 mg/L for 2,4-D. This is more than ten times the guideline for the protection of aquatic life of 4 mg/L. The three most commonly detected compounds in the storm drain samples were 2,4-D (92% of 39 samples), MCPP (mecoprop) (85%), and dicamba (82%). Eleven of the 13 compounds detected have established guidelines. The compounds that did not meet irrigation guidelines were dicamba (31 times), MCPA (12) and bromoxynil (1). Those not meeting guidelines for the protection of aquatic life were MCPA (1), lindane (3), 2,4-D (2), atrazine (1) and malathion (1). Further Information Required This data will be placed in context of land use in each drainage area, as well as in terms of flow and volume, in order to assess the impact of the pesticide load contributed to the Oldman River from the urban drainage system. What Do These Findings Mean? This is only preliminary data, but the information so far indicates that we are finding pesticides in storm drains emptying directly into the Oldman River. What Can I Do to Help? All urban residents are encouraged to handle and use pesticides responsibly. This means using them according to the instructions on the label, not pouring "grey"/contaminated/polluted water and/or chemicals down the storm drain, and not over watering lawns and sidewalks. Watch what you throw down the sink and street drains! Pesticides and herbicides can kill beneficial bacteria in the sewage treatment plant. These materials should be disposed of through your local toxic round-up program. Limit the amount of chemicals you use on your lawn. Once applied in excess, they persist in the turf and soil. When water is applied they are carried with the runoff into the storm system and ultimately to the Oldman River. Do not water excessively. Once lawn watering has saturated the soil and turf, the remainder of the water that is applied becomes surface runoff. This runoff ultimately finds its way onto the streets and into the storm water system, carrying whatever pollutants it picks up on the way. Do not dump anything into catch basins or manholes. The City of Lethbridge holds Residential Toxic Roundups once a month, at which time residents may bring household hazardous wastes for proper disposal. For more information, call the City of Lethbridge at (403) 329-7367. If you notice a problem, report it immediately to the City at (403) 320-3850 or Alberta Environment at 1-800-222-6514, so that a proper clean up can occur. Check out the following web sites for information on water, water quality and waste: City of Lethbridge Alberta Environment Research and Education Alberta Environment Water Management Alberta Agriculture, Food and Rural Development Action on Waste - Household Hazardous Wastes Bow River Basin Council Emerging Issues Water Environment Federation Water Quality Information Center: National Agricultural Library Office of Waste Water Management: Animal Feeding Operations Return to Top