IN THE GARDEN

Is tainted water OK for plants? Yes and no

Kelly Heidbreder

Algae have been quietly blooming in Lake Erie for years.

The shallow water, combined with the summer heat and light winds make it easy for the algae to thrive. But this year it shut down the Toledo water supply and caused quite a ruckus. 

Ohio State University scientists say it is OK to water your lawn and flower gardens with the water, but it can cause problems in your vegetable garden.

Toxin tainted water

Hundreds of thousands of friends and neighbors across northwest Ohio and southeast Michigan have had to avoid tap water for drinking, cooking, and washing dishes. And what made the water crisis even worse, the water couldn’t even be boiled to make it clean enough to consume.

The algae produces microcystin and this toxin stays in your water. Boiling the water only concentrates the toxin. Evaporation concentrates the toxin.

A sick garden

So how does all of this translate to the garden? We have been watering our lawns for months this summer, and for years past. If you live in this water crisis zone, you have been watering with water that has traces of microcystin as the algal blooms have grown in strength and concentration.

The plants might not look sick, but they could carry traces of toxin that has soaked into them during irrigation. Tests are still being done to see how much stays in the plant and how much can make you sick. 

Scientists at the Ohio State University are looking into the long-term effect of watering your garden with toxin-tainted water. 

“One question is, how long does the toxin remain in the water and how does it transfer into the food we are consuming?” said Amy Stone, Ohio State University Extension Agent for Lucas County. “Right now, we are recommending that people not use the tap water to water their garden.” 

Jiyoung Lee, PhD, Associate Professor of Environmental Microbiology, says the microcystin has shown up in plants irrigated with the tainted water. “It has been known that the toxin can be absorbed by plants [such as alfafa and wheat]. The most of the toxin is found in plant roots; shoots have much lower level of the toxin. For fruits, the toxin ending up in the fruits would be very low.” 

Drip irrigation at the root line would have a lower chance of transferring the toxin to the leaves of the plant, according to Ms. Lee. 

“Eating leafy greens would not be proper if irrigated with the toxin-contaminated water. But most places, they don’t use surface water that contain high level of toxins for irrigation. If irrigated with ground water, the risk would be low,” Ms. Lee said.

Lake scum

The Minnesota Department of Health did a study on microcystin use in the garden in 2011. Minnesota has a similar problem on Little Rock Lake. They tested many things including the foam that washes up on shore, called scum.

Scum of the microcystin can contain high concentrations of toxin for months. Then when the scum is picked up by a wave and sucked back into the lake, it releases those toxins back into the water. According to the World Health Organization, this algae scum has the highest risk of making someone sick. According to this study, ingesting the scum could cause acute liver injury in a child. “Children are at a greater risk from cyanotoxins than adults because of their lower body weight and their increased likelihood to ingest water during swimming/wading in water.”

This study found that there is a slim chance to come in contact with the toxin while watering your yard and garden. The water could cause a skin reaction or be breathed in while you are spraying. But they don’t know how much you would have to touch or how much you would breathe in make you sick. Scientists say it takes a high concentration of microcystin to show signs of liver injury in a child.

Bottom line

It is safe to water your lawn and flower gardens. Tap water during a high algal bloom isn’t safe to drink unless water treatment processes can remove the microcystin. Toxins can stay in leafy green plants, but most plants store it in their roots, making the fruit of the plant OK to eat.

I will keep on bugging the scientists for more information. But until then, Ms. Lee says to toss the leafy vegetables such as lettuce, cabbage, chard and Brussels sprouts. But it is OK to eat your the other veggies.

Contact Kelly Heidbreder at getgrowing@gmail.com