Sunny days, fertilizer runoff and sewage can create toxic bacteria at Salton Sea

Hot weather is on its way, and with it, potentially toxic bacteria could bloom rapidly in California’s largest lake, the Salton Sea, and other waters on the receiving end of runoff from farms and golf courses or sewage spills. With temperatures across the desert expected to climb high into the 90s by Monday, experts say telltale signs will quickly appear. 

Algae mats, foamy scum and off-color water all can contain microscopic cyanobacteria that gobble up fertilizers or waste and, using the sun for photosynthesis, explode with new growth. While many of the bacteria are harmless, some spawn nasty toxins that can cause convulsions, liver damage and other serious health concerns, officials say. 

"As we head into warmer weather, what people should look for is discoloration that doesn't match surrounding water, especially scum or foam on the surface or the shoreline. Those are the really possibly hazardous areas you want to avoid," said Jeff Geraci, senior environmental scientist with the California Regional Water Quality Control Board, which oversees the Colorado River region. Geraci has done testing at the Salton Sea for two years.

Most at risk are pets and children, who may play in shallow waters and accidentally drink or inhale dangerous toxins. There is no known treatment for exposure.

"Dogs are very attracted to scum. Even if they don't eat it, they're going to lick their fur and ingest cells that contain the toxins," said Geraci. "What you’ll observe in the animal is they go into convulsions and within an hour they're usually dead."

The problem is growing up and down California and around the world, experts say, typically wherever industrial agriculture is situated near water. A spot like the Salton Sea, which exists because of agricultural runoff and an often sewage-polluted river, and which enjoys long, sunny days and often still waters, is an ideal possible breeding ground. To date, levels of detected toxins there have been low, but they're there — enough on occasion to trigger caution signs, but not full closures or danger signs. 

"We do have cyanobacteria at the Salton Sea ... seven different species. As far as toxins, we've observed three: anatoxin-a, microcystin and saxatoxin," said Geraci.

Anatoxin-a and saxatoxin are potent nerve poisons, and microcystin has been connected to symptoms ranging from sore throats to severe liver damage. Just like green plants, all thrive when an overabundance of nutrients exists — particularly phosphorus from fertilizer runoff.  

"In the warmer months it's much more prevalent, because cyanobacteria prefer ample sunlight, full sun, and they like warm, calm waters," Giraci said. "Some are naturally occurring, but the majority comes from the fertilizers from the agriculture there."

While the levels observed so far are below World Health Organization amounts identified as dangerous, Geraci said, "just keep in mind, blooms can occur rather suddenly, with the potential to change to toxic conditions just as quickly."

And as the sea shrinks due to the diversion of waters to urban areas, more of the cyanobacteria and other contaminants that currently lurk in the deeper benthic zone could be exposed, he and others said. 

Cyanobacteria, sometimes called blue-green algae, have been around for billions of years, and can also be red, purple, brown or pink. They can live in everything from snow to the ring of water around a lawn sprinkler. But as large-scale agriculture and improved testing technology have surged, "toxic algae" are being recognized as a growing problem worldwide. Phosphorous and nitrogen are the main culprits, and can be present in human or animal waste too.

The exact mechanism that causes poisons to develop where farm runoff and warm water collide is being researched, but several studies have established the link, said Thomas Van Lent, director of science and policy at the Everglades Foundation in Palmetto, FL. He compared the runaway spread of bacteria when conditions are right to a forest fire.

"We don't know exactly what the spark is," he said, "but the fuel is always the same thing: fertilizers."

The results of exposure can range from heartbreaking to costly. Last summer, pet dogs died in Fresno and New Brunswick. Humans have suffered painful liver bleeding deaths in China. And in Brazil, 76 kidney dialysis patients died after intravenous exposure to microcystins in untreated water. New national water quality regulations were developed there as a result.

Florida's Lake Okeechobee, one of the largest lakes in the U.S., as well as its tributaries and drainages to the Gulf of Mexico and Atlantic Ocean, are now often covered with "guacamole thick" algae, Van Lent said, costing resort and tourist towns millions of dollars in lost revenue.

Toledo, Ohio's drinking water was shut off for three days in 2014 due to harmful cyanobacteria. After paying millions for municipal treatment and still being exposed due to agricultural runoff into Lake Erie, residents are trying a novel approach. This February, they voted to approve an amendment to the city charter that recognizes the Great Lake as having legal rights —  giving the lake the same protections as a person. In response, a fifth-generation farming family sued the city, saying the initiative threatened their ability to properly fertilize fields because it could not guarantee that runoff would not enter the Lake Erie watershed.

Major agriculture groups have fought tougher regulations for decades. In the United States, farming activities have largely been exempt from the Clean Water Act since it was adopted in 1972, Van Lent said. Along the Salton Sea and elsewhere, conditioned waivers from state water laws allow runoff, but cap amounts of certain contaminants or use "best management practices" by growers and others. Regional water quality board executive officer Paula Rasmussen said officials are examining requiring permits instead of waivers, in some cases.

With little appetite in Congress or in many state legislatures for clamp-downs on farm runoff, Van Lent said the Everglades Foundation is now offering a $10 million reward to whoever develops a technology to cheaply remove phosphorus, the main culprit, from freshwater bodies.

Closer to home, there have been no reports of related illnesses in the communities along the Salton Sea, said Jeff Lamoure, the deputy director for environmental health at the Imperial County public health department. Residents do suffer high rates of asthma and allergies. Nellie McConell, who's lived a few hundred feet from the lake in Desert Shores since the 1980s, said her doctor told her that persistent nasal irritation and a polyp might be linked to dust from the dried playa. 

Massive die-offs of a migratory bird called the eared grebe occurred in the 1990s at the Salton Sea, with 150,000 dead in a single year. While researchers initially suspected avian cholera, a 2005 paper pinpointed microcystin - a poisonous form of algal bloom - in the livers of birds.

Testing of lake water during warmer months began two years ago, and caution signs have been posted when a high enough level triggers them. With growing concern from elected officials and residents, county public health staff held a community meeting in Desert Shores in late February.

Residents near the evaporating lake try to balance awareness of the risks with their love of the sea's dramatic and ever-shifting landscapes.

"That's brown algae right there," said Jasmyn Phillips, a longtime Salton City resident who kayaks on or walks along the western shore of the lake several times a week. She knows the warning signs well. But on a recent bright, calm afternoon, she couldn't stop herself from wading through muck to rescue a struggling painted lady butterfly out on the lake. When she reached the shore, and after the butterfly had fluttered away, she carefully poured bottled water over her legs and feet and wiped them clean.

But visitors from around the world who visit, sometimes to let their dogs run or their children romp, may not know about the risks. New, coordinated state and county programs could help. Lamoure says the county will soon be posting sturdy, permanent educational signs about toxic algae at popular public entry points around the lake. He said the aim is to augment state signage and surveillance.

Geraci said his annual funds for water monitoring have run out, but given the early onset of scorching heat, he'll probably dip into emergency funds to do some testing this month. Once a new fiscal year begins and the summer arrives, he and others around the state will resume regular monitoring. Last year, both Diamond Valley Lake near Hemet and Lake Elsinore experienced heavy blooms and temporary closures.

It's tougher to close off recreation at the Salton Sea, which measures 15 miles wide by 35 miles long. And as it dries, more hazardous substances could be exposed, including cyanobacteria. Although they dissipate more readily than legacy heavy metals and pesticides, they also can be more concentrated. In the past two years, California and Imperial County officials have begun monitoring programs. The California Harmful Algal Blooms Portal collects data from regional inspectors and posts them on a map online.

Imperial County supervisors earlier this year directed environmental health staff to create a water desk to address risks, with a focus on the Salton Sea. Biochemist Tom Sephton did a historical assessment of toxics in the sea's sediment and water column, and is finalizing a recommended program for Imperial County.

He, like Geraci, said the highest concentrations of contaminants are either in sediment on the lake bottom or in the deeper portions of water. But he agrees that as the lake continues to rapidly evaporate, dust from the playa could unleash new toxics, including those found in cyanobacteria.

A partnership between the regional water quality board, the Imperial Irrigation District and local farmers to cap sediments appears to have cut down on the thick mats once present in the sea, Sephton said. Geraci said while it could have helped somewhat, it didn't eliminate the problem. IID did not respond to a request for comment.

To be safe, the advice from the experts is simple: If the water doesn't look right, stay away.

"Walk a few hundred yards down the beach instead," advised Sephton. "And don't let your kids go in it."