Toxic algae place Vancouver’s St Mary Lake off-limits early in the season

23 May 2012

St Mary Lake in Vancouver has worked up some cyanotoxin levels, enough to get the lake closed almost before the season has started [Source: GulfIslandsDriftwood].

Total microcystin levels in untreated water tested by the Highland Water Service District between December 12, 2011 and April 17, 2012 have ranged from 19.41 ug/L (micrograms per litre) to 30.8 ug/L.  According to World Health Organization recommendations established in 2003, recreational exposure to microcystin concentrations greater than 20 ug/L represent a health risk to humans. The WHO suggests contact with water containing more than 20 ug/L of microcystin be avoided.

Microcystin LR levels range from 1.86 ug/L (micrograms per litre) to 2.89 ug/L. Hewitt notes that these levels exceed the federal government’s recommended lifetime consumption guidelines of 1.5 ug/L.   The approximately 53 lakeside property owners who draw water directly from the lake are especially vulnerable to the dangers posed by elevated microcystin levels.

Grayson County in Texas has adopted a whole new algal warning system.  The new warning system will consist of colored signs.  Green means there is no advisory. Yellow means there is a watch, and people should take extra precaution. Red means the amount of blue green algae is sufficient to cause injury to humans and pets.

Currently, the Army Corps of Engineers is the only agency that warns the public of the blue green algae on Lake Texoma. Now Grayson County will post it’s own signs next to the Army Corps signs. The Corps is testing for algae content levels and the health department is testing for toxin levels.

Additionally, the USACE will be providing some additional information [Source: Fox23.com]

Instead of the advisory and warning signs used last year, the Corps will post an educational sign throughout the summer at all Tulsa District reservoirs with information about blue-green algae.

Once a suspected blue-green algae bloom is reported by the public or lake staff and test results indicate levels exceed 100,000 cells per milliliter of water, a blue-green algae awareness level advisory will be issued and advisory signs will be posted lake-wide. An advisory indicates that there is an elevated risk of adverse health effects because BGA is present.

At the advisory level, children and pets are more likely to get sick because of blue-green algae, and pets and livestock should be kept off of the beach and out of the water. The Tulsa District advises members of the public not to drink untreated lake water and to use caution when swimming, water skiing and coming into contact with lake water. Visitors should also avoid areas with visible algae accumulation or discolored water.

Once tests indicate levels have fallen below 100,000 cells/ml of water, the advisory will be lifted.

In addition to signage, the Corps is also developing a blue-green algae section on its website, which is expected to launch soon.

Ojai (yes, this is how it is spelt) Valley in California is planning a debate on water quality issues and eutrophication is right up there at the top of the list! (where it should be) [Source: Ojai Valley News Blog].

At issue is the amount of nutrients in the watershed. These can result in excessive algae blooms that choke the river and cause the levels of oxygen to fluctuate. “The Clean Water Act requires all waterways to be fishable and swimmable,” explained Ojai’s Public Works director and engineer Greg Grant.

The sources of these algae-promoting nutrients (essentially, pollutants) are many — livestock manure, farm fertilizers, disposal of wastewater and sludge from water treatment plants, runoff from storm drains, and even natural sources that can leech out of the mountains over time. The Environmental Protection Agency has set a deadline of March 2013 for local water quality control boards to develop and adopt plans for reducing the amount of pollutants, hence the May 30 meeting.

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