July 27, 2012 15:14
BY MURRAY FEIST, RUMINANT NUTRITION SPECIALIST
Weather conditions this summer have been conducive to the formation of blue-green algae blooms on dugouts and ponds. Nutrient rich runoff flowing into a body of fresh water combined with warm daytime temperatures in the summer accelerates algal growth, including that of blue-green algae.
Blue - green algae is not an algae, but a bacteria called "cyanobacteria." This bacteria produces toxins that can cause skin and eye irritations, gastroenteritis, liver and nervous system damage, sickness and, at times, death.
A surface bloom of blue-green algae may look quite differently depending on which species is dominant. Some will have a shimmering blue-green colour. The bloom may also have a foamy sheen-like appearance that looks like spilled paint floating on top of the water. Heavy blooms may appear like a solid shimmering blue-green sheen across the water’s surface, may have an appearance and consistency similar to pea soup, or may have a mixture of the colors tan, purple, grey, green or blue-green.
If blue-green algae is identified in a water source, all livestock, pets, and human contact should be prevented. The water will require treatment.
The most common treatment of blue-green algae in an open dugout or pond is with a registered product containing copper sulphate. A treatment rate of one pound (0.45 kilogram) of copper sulphate (by weight) will treat 100,000 gallons (1 kg/1,000,000 litres). There are two common application methods: the copper sulphate can be dissolved in warm water, which is then sprayed over the water’s surface; or, the copper sulphate can be weighted into a cloth bag with a rope spread from side to side, and with the assistance of another individual, the bag can then be dragged back and forth across the water’s surface. When treating dugouts, the objective of the treatment is to target the top meter (1.0 m) to kill the algae.
Copper sulphate works by killing the blue-green algae. Doing so releases the blue-green algae toxins into the water. Therefore, it is recommended that 12 to 14 days should pass prior to any livestock, pet and/or human contact with the contaminated water. If treating a dugout containing fish, it is recommended that only one-third of the dugout should be treated, using one-third of the recommended copper sulphate weight applied in treatments over a three day period.
The treatment process described above applies to non-draining waterbodies, such as dugouts, which are wholly contained on private land. In the case of waterbodies that drain to adjacent properties or waterways, a permit for the chemical control of aquatic nuisances is required from Saskatchewan Environment.
For more information, call the Agriculture Knowledge Centre at 1-866-457-2377.