when i was growing up, one of junie’s favorite spots to explore was the hike-and-bike trail around lady bird lake in downtown austin. of course, every visit ended in a trip to the water. junie’s dusty paws would bound down the familiar paths as she glanced back every few yards to make sure i was following behind. she would approach the lake’s edge warily, then gingerly step in to cool off from the scorching texas sun and gulp down a refreshing mid-afternoon drink. when heading home she would leave a trail of muddy paw prints in our wake, refreshed and happy.

today, though, a visit to the water may end differently. 

in 2019, austin’s lakes saw a sudden increase of harmful algae blooms (habs) that tragically resulted in several dogs’ deaths and led to residents avoiding any contact between their pets and local bodies of water. no deaths — dog or otherwise — have been reported in austin since 2019, but hab events continue to occur across the city and pose a major threat to public health.

austin’s habs involve blue-green algae called cyanobacteria. this algae is naturally occurring but proves toxic in certain forms. in humans, the health effects of cyanotoxins may first appear as common cold or flu symptoms like fever, headache, and vomiting. indicators in dogs include weakness, and respiratory paralysis, which can lead to death.

in late september of this year, toxic levels of cyanobacteria were found in one part of barton creek, a popular local swimming area. though levels have since dropped to safer amounts, both lady bird lake and lake austin, which sits northwest of the city down the colorado river, have recently displayed concerning levels of toxic algae. 

as human-induced climate change continues to threaten our day-to-day lives, habs like austin’s will only happen more often. cyanobacteria thrive in environments with warm waters and high concentrations of carbon dioxide — two major consequences of global warming.

increased water temperatures lengthen the growing season and widen the geographic range of algal blooms. texas has already seen a 1 to 2 degree f increase in annual average temperature since the early 20th century. scientists project that annual average temperatures in the southern great plains will further increase 3.6 to 5.1 degrees f over the next 30 years, potentially worsening the effects of habs over time.  

nutrient pollution is another related factor. this phenomenon occurs when nutrients mix with rain runoff and seep into bodies of water. phosphorus and nitrogen are the most common pollutants and can result in excessive algae growth and enhanced toxicity. in turn, overgrowth of algae causes low oxygen levels in the water, affecting the entire ecosystem by killing fish and inhibiting aquatic plant growth.

in june, the austin city council unanimously voted to launch a pilot project to mitigate the effects of harmful algae using phoslock, a material that chemically binds the phosphorus in water and sediment into a mineral form so that blue-green algae cannot obtain its nutrients. this five-year-long, $1,484,000 contract with the sepro corporation includes water collection and analysis as well as three phoslock applications across 20 acres of water around lady bird lake. city officials have not disclosed the status of the project since it was first announced.

austinites should remain wary of areas displaying blue- or bright green-colored algae and stay up-to-date on the fluctuating risks of local bodies of water via the city’s monitoring systems. now, on my visits home, i can’t explain to junie why i now steer her away from the water’s edge on our walks, but at least i can take comfort in the fact that i’m doing my best to keep her — and myself — safe.

washington – global warming will fuel the overgrowth of harmful algal blooms in lakes and reservoirs, affecting the northeast and southeast most significantly, according to a new study.

using a detailed modeling framework, steven chapra, a tufts university environmental engineering professor and the lead author of the study, said he and his team predicted that the northeast would sustain the greatest increase in harmful algal blooms and recreational regions in the southeast would suffer the biggest economic consequences. the study was published in the august issue of environmental science & technology.

warm waters and increased nutrients allow cyanobacterial harmful algal blooms, which occur in freshwater bodies and estuaries, to thrive.

when temperatures increase, precipitation patterns change and storms become more extreme, chapra explained. increased precipitation leads to more erosion and more nutrients in freshwater bodies, particularly in rural regions, he said.

according to the environmental protection agency, exposure to harmful algal blooms can cause health problems ranging from vomiting to pneumonia. in 2014, residents of toledo, ohio were banned from using tap water as a result of toxins produced by harmful algal blooms.

“the most dangerous impact of these cyanobacteria is when they become toxic and pose significant health risks to both drinking water supplies and recreational use of the water,” said don scavia, professor of civil and environmental engineering, at the university of michigan.

since the freshwater systems in the northeast region have historically been cooler, climate change will cause the region to have the greatest increase in harmful algal blooms.

but in the southeast, more people rely on freshwater systems for commercial and recreational purposes, including fishing, hunting and swimming, chapra said. the study estimates that between $57 and $110 million may be lost annually in the southeast by 2090 due to the loss of recreation days alone.

“some of the biggest cyanohab impacts will occur in more rural regions, such as those in the southeast and midwest – areas that don’t often come up in conversation about unavoidable effects of climate change,” he said in a news release.

homeowners with property on water are likely to see decreases in the value of their homes if the waters are crowded with “unsightly” blooms, chapra said. and because fish can’t eat the blooms, they end up on the shoreline, affecting air quality because of their sulfuric smell.

in studying the economic impact of the blooms, he and his team only looked at the number of recreation days lost due to harmful algal blooms. although drinking water impacts were excluded from the study, the authors noted that those are likely to be important, particularly for regions without advanced water treatment systems.

tim davis, associate professor of biological sciences at bowling green state university, said that although the study focuses on the u.s., harmful algal blooms have the potential to damage water supply all around the globe. he cited a 2007 crisis in wuxi, china, when millions of residents were unable to access clean water for a week.

“the potential impacts become much greater because these blooms are occurring in more places, and becoming more severe, which just increases the chance of humans or animal health being impacted,” davis said. “it’s going to negatively impact the economy, people’s health, people’s lives, and it’s going to continue to grow as a problem.”