Except for an area off the Ga. 53/Dawsonville Highway bridge in Gainesville over the Chattahoochee River, Lake Lanier met water quality standards in 2013.
The testing station at the bridge showed 10.6 parts per billion of chlorophyll-a, which indicates the level of potentially harmful algae growth, exceeding the standard of 10 parts per billion, according to data collected by Chattahoochee Riverkeeper, an Atlanta-based environmental watchdog group.
An average of monthly results from five locations on Lanier also showed water quality violations at Buford Dam.
However, after crunching numbers supplied by the Georgia Environmental Protection Division, final calculations showed Buford Dam was no longer in violation, said Jason Ulseth, the organization’s technical programs director.
The other testing sites are off Browns Bridge that straddles Hall and Forsyth counties, an area between Aqualand Marina and Three Sisters Island, and Boling Bridge on Ga. 53/Dawsonville Highway over the Chestatee River.
Each April through October, Chattahoochee Riverkeeper cruises Lake Lanier checking water quality, as part of a sampling and quality assurance plan approved by the EPD. The state agency releases an impaired water list every two years in compliance with the federal Clean Water Act.
“We expected to see higher levels of algae this year compared to last year because of high rainfall and resultant stormwater runoff,” Ulseth said.
“As rainwater washes into the lake, it can carry various nutrients from fertilizers, agricultural lands and septic systems, which may result in a greener lake,” he added.
“The data shows that there is a continued need to address stormwater runoff and to implement better controls to prevent excessive amounts of nutrients from washing into the lake.”
Ulseth has said the northern end of Lake Lanier tends to be murkier because of the joining of the Chestatee and Chattahoochee rivers.
“As the (rivers) are coming in, they’re depositing all the nutrients from that whole watershed and they all get eaten up on that end,” he said. “Generally, we see the clearest water at (Buford) Dam.”
Lakes tend to store nutrients such as nitrogen and phosphorus that flow from “point sources,” or identifiable areas, such as government-run sewer plants.
But they also flow from “nonpoint” sources, such as septic tanks, lawn fertilizers and runoff. Pollution gets into streams, which eventually wind their way to the lake.
“As these nutrients collect in the lake, a main concern is that excessive amounts of algae may begin to grow in the lake and have devastating impacts,” states the Chattahoochee Riverkeeper website.
The Centers for Disease Control and Prevention in Atlanta says algae blooms “can produce toxins that are harmful to the health of the environment, plants, animals and people.”
Under federal law, states must develop “total maximum daily loads,” a calculation of the maximum amount of a pollutant a body of water can receive and still safely meet water quality standards, according to the U.S. Environmental Protection Agency.
EPD will use the water quality data “to help identify priorities as it prepares to implement its watershed cleanup plan that has been in the works for over five years, since the lake was listed as impaired in 2008,” Ulseth said.
Chattahoochee Riverkeeper plans to continue monthly sampling trips again next year.
“Long-term data is necessary to document changes in lake water quality and determine if cleanup efforts are effective,” Ulseth said.