Lake Lanier contained more algae in 2019 than in the previous 20 years, according to data reported by Chattahoochee Riverkeeper.
“Our region’s prosperity depends on a healthy Lake Lanier,” Dale Caldwell, Chattahoochee Riverkeeper’s headwaters director, said in a statement. “The high algae levels that we saw in 2019 indicate that we need to do a better job of controlling the amount of nutrients flowing into the lake.”
When excess nutrients flow into the lake, algae blooms in the water. Chlorophyll is the main indicator used to detect that algae.
Pollution flowing from industrial facilities, agricultural operations or sewage treatment plants, as well as stormwater runoff, can cause too much algae to bloom in the water.
Too much algae in the water can negatively affect water quality and affect the taste and smell of drinking water. It can also raise the cost of treating the water and deprive aquatic life of the oxygen it needs.
Chattahoochee Riverkeeper has been testing chlorophyll levels at 10 locations on Lake Lanier once a month between April and October since 2010, and the environmental group monitors algae levels in accordance with a Sampling and Quality Assurance Plan approved by the Georgia Environmental Protection Division. The EPD also collects water samples and has been monitoring the lake since 2000.
Data collected by Chattahoochee Riverkeeper is averaged with data collected by the EPD and Gwinnett County’s Department of Water Resources. Between 2000 and 2018, these monitored chlorophyll levels increased at an average of 0.17 microgram per liter each year. Between 2018 and 2019, however, the increase was about 3.72 micrograms per liter.
Linda MacGregor, director of Gainesville Water Resources, said the department can adjust its water treatment process to adapt to changes in chlorophyll levels, but it has not become an issue yet.
“The chlorophyll levels are not a big problem for our water treatment plants to handle to produce safe drinking water. … Even though these are the highest levels that have been measured in the lake, it’s not a problem for our water treatment plants,” she said.
Many industries discharge their wastewater into the city’s system, and the water resources can then treat the water before discharging it, MacGregor said. Some industries do have their own discharge permits. Phosphorus is removed from wastewater discharged back to the lake, and the city has been able to reduce phosphorus levels over time, she said.
“We’re really committed to reducing the nutrients that are going in the lake,” MacGregor said.
The EPD has published a cleanup plan for Lake Lanier that identifies the discharge of treated wastewater as the main source of nutrients leading to algae. Fertilizers, agriculture and failing septic tanks are listed as other sources. The cleanup plan includes ideas such as working with county health departments on proper installation and maintenance of septic tanks, educating the public on fertilizer use, and controlling erosion. The full plan is available on the EPD website.
Chattahoochee Riverkeeper plans to work with local governments and utilities to help implement the plan.
“This alarming spike in chlorophyll levels highlights the need for this cleanup plan,” Riverkeeper Jason Ulseth said in a statement. “We will be doing everything we can to make sure that those who manage the sources of the excess nutrients flowing into Lake Lanier are taking action to address this public health threat as quickly as possible.”