The harmful toxin found in Lake Erie that caused a water crisis in Ohio’s fourth-largest city this weekend has raised concerns nationally. That’s because no states — including Texas — require testing for such toxins, which are caused by algal blooms. And there are no federal or state standards for acceptable levels of the toxins, even though they can be lethal. 

In Toledo, Ohio, where voluntary tests at a water treatment plant found elevated levels of the toxin microcystin, which is produced by blue-green algae, the city is urging residents and the several hundred thousand people served by its water utility not to drink tap water, even if they boil it. Exposure to high levels of microcystin can cause abdominal pain, vomiting and diarrhea, liver inflammation, pneumonia and other symptoms, some of which are life-threatening. Restaurants have closed and there are shortages of bottled water as far as 100 miles away. 

In Texas, which has battled blue-green algae problems at several of its lakes, Terry Clawson, the spokesman for the state’s Commission on Environmental Quality, said surface water data has “not demonstrated levels of algal toxins that show any cause for alarm.”  

But he said the agency “considers it important to continue screening available data to determine if additional monitoring and evaluations are needed,​” and is screening “selected reservoirs” for blue-green algae and microcystin. It is also waiting to review data collected over several years by the U.S. Geological Survey on many different Texas lakes. 

The crisis in Ohio is likely to prompt policy changes there. That’s because algal blooms are becoming increasingly common in Lake Erie, the water supply for 11 million people living around the Great Lakes.

In Texas, state guidelines suggest notifying the public of potential swimming hazards if microcystin levels in recreational waters are found to be above 20 parts per billion. But regulators have no plans to draft standards that address algal blooms by requiring testing or identifying acceptable levels of the contaminants in water, even though the state has identified algae and and its resulting toxins as an emerging concern.

After a scare over algal blooms and water quality for recreational users of Lake Texoma, local officials last year asked for input from several different Texas agencies about their views on blue-green algae. Clawson said cell counts for blue-green algae in Texoma, which the agency is now monitoring, are sometimes elevated, but “microcystin occurrence has been relatively low.”

Recently, Houston had issues with blue-green algae in Lake Livingston and the Trinity River, which caused elevated levels of naturally occurring chemicals that were not toxic or unsafe for drinking — but prompted a foul odor. Even though those chemicals were nontoxic, scientists say they know little about when and why algae produces toxic versus nontoxic chemicals.

Waco has also struggled with blue-green algal blooms for years, and the problems there may be more serious. The city already spent tens of millions of dollars to lower concentrations of nontoxic chemicals that changed the taste or smell of the water. More recently, however, microcystin has been detected in Lake Waco — but Waco says its treatment plant so far has the technology to address the problem. Treatment plants have a limited ability to get rid of such toxins, but it is expensive and there is no standardized method.  

The most recent data on microcystin testing in Texas is from a 2007 federal assessment that included many Texas reservoirs. They showed levels of microcystin that were very low — under 1 part per billion.