GRAYSON COUNTY, TX -- If you're at Lake Texoma for the holiday weekend, you might see a green sign posted around the lake.
It's part of Grayson County's new evaluation system for blue green algae in Lake Texoma, based on a 16-month study by the Grayson County Health Department.
Like a traffic light, it measures the levels of blue green algae and classifies them by green, yellow or red.
Right now, they're at green.
"And we've never gone to a level yellow based on toxins these algae could potentially produce," said John Teel, Grayson County Health Director.
Toxin levels are the subject of the 16-month study. They presented the findings to county commissioners this week - specifically that toxins are the problem.
"They're essentially not there, it's right down around the detection limit of 1/10 of 1 part per billion," Teel said.
Teel said for a code yellow warning level - basically a caution - toxins would have to be 5 parts per billion.
"It's no secret that the Grayson County Health Department's scientific analysis differs from that of the Tulsa district of the US Army Corps of Engineers."
In 2011 the Corps determined lake water was unsafe, based on blue green algae cell counts.
Assistant Lake Manager B.J. Parkey said their methods changed last year with Oklahoma Senate Bill 259, which took toxin levels into account when setting safety standards instead of relying only on cell counts.
"It's gonna be possible difficult to get that type of concentration in Lake Texoma," he said.
And that's good news for Lake Businesses, which lost millions of dollars in revenue in 2011.
GrandPappy Point General Manager Jason Cottingame said they're predicting a successful year in 2013.
"The County has been great for us. The County has gone above and beyond to do testing for us and just confirm that this blue green algae that exists in every lake is not toxic to us or our pets."
And as Cottingame gears up for memorial day weekend, the County is rushing to install the new green signs before boaters hit the lake.