Demystifying the complex world of water: Your questions, answered

Here are answers to your most-common water questions
You asked, we answered. Here are five of your most-common questions related to water, answered by MPR News reporters. Here, the Grassy Bay Cliffs rise up out of Sand Point Lake in Voyageurs National Park.
Evan Frost | MPR News file

From quality to regulations to usage, there's a lot to know about water in Minnesota. So, MPR News wants to know what you're curious about regarding water.

This summer, we asked people at the MPR News State Fair booth to give us their questions on water. Reporters Kirsti Marohn and Cody Nelson researched answers to five of them and are ready to tackle yours. You can pose your question using the form at the bottom of this story.

Click a question to jump to the answer, or scroll through the entire list.

What's the most polluted lake in Minnesota?

How many people can't drink their water at home safely?

Do you have the rights to the water beneath your property in Minnesota?

How often do municipal drinking water supplies get tested for lead?

What are the biggest threats to clean drinking water?

When lake temperatures warm, blue-green algae thrives.
A blue-green algae bloom on Peltier Lake, near Lino Lakes, Minn., seen last summer.
Dan Kraker | MPR News file

What might be lurking in your drinking water depends on where you live, according to Tannie Eshenaur from the Minnesota Department of Health.

In some places, nutrients like phosphorus are causing harmful algae blooms that can contaminate lakes and rivers. Those nutrients can come from fertilizer runoff, wastewater treatment plants or failing septic systems.

Contaminants called cyanotoxins can be produced during an algal bloom that can sicken people or pets. To date, Eshenaur said the health department hasn't found any cases of cyanotoxins exceeding safe levels in treated drinking water.

Nitrates in drinking water are a growing concern in Minnesota, especially for infants fed formula made with tap water. High nitrate levels can cause blue baby syndrome, which can be fatal.

Nitrates are linked to fertilizer used on farm fields and lawns. Eschenaur said the number of Minnesota public water supplies that have had to treat their ground water for nitrates has risen to eight, which serve a total of 50,000 people.

For the first time in 2016, a city that gets its drinking water from a lake or river exceeded the federal level for nitrate, Eschenaur said. That happened in Fairmont, which relies on Lake Budd for its drinking water.

There's also growing concern about contaminants from products humans use every day, from pharmaceuticals to personal care products. When they go down the drain, they end up in the water eventually used for drinking.

There's also concern about lead contamination in water, especially in older homes. Eschenaur recommends flushing out the pipes first thing every morning or if you've been gone for a few days.

If you want to find out more about what's in your drinking water, the Minnesota Department of Health publishes an annual report, as do individual public water systems.

— Kirsti Marohn

What's the most polluted lake in Minnesota?

Algae bloom at Sailboard Beach on Lake Okebana.
Pollution control staff said they couldn't pick one most-polluted lake. Here, an algae bloom on Lake Okabena in Worthington, Minn.
Courtesy of Dan Livdahl 2013

When pitched this question, staff at the Minnesota Pollution Control Agency were reluctant to answer.

That's because it's tough define "most polluted," said Cathy Rofshus, a Minnesota Pollution Control Agency spokesperson. It could mean the lake with the most impairments. Or the longest trend of harmful algal blooms. Or the most industrial and sewage pollution.

Plus, water conditions change often, making it more complicated to gauge water quality.

For example, "you could have a hot, dry summer and have a lot of algae blooming in a certain lake and then the next year you can have different weather and it'll be pretty good."

There is a geographic trend in lake pollution, however. In 2015, the MPCA released a report called "Swimmable, fishable, fixable?" at the midpoint of a massive statewide water-quality study.

The report showed "excellent" water quality in northeast Minnesota, Rofshus said. "And then as you go south, southwest, it just gets worse and worse."

Why is this the case? "It's a direct reflection of land use," Rofshus said.

In the northeast, wetlands are still intact, there are acres of undeveloped land, more forests and less runoff into waterbodies, Rofshus said.

As you move down the map toward the Twin Cities and agricultural southern Minnesota, it all changes. There's heavy development and agriculture changing the landscape — and the water.

— Cody Nelson

How many people can't drink their water at home safely?

Testing for arsenic
Emily Berquist, a hydrologist with the Minnesota Department of Health, attaches water testing equipment to a well at a home in St. Michael, Minn.
Jennifer Simonson | MPR News file

It depends on where you get your water.

For about 80 percent of Minnesotans, their drinking water comes from a public water system, according to Chris Elvrum with the Minnesota Department of Health.

Generally speaking, water from public systems is usually safe. Cities must meet the federal Safe Drinking Water Act, which sets "safe" levels for 100 chemicals and microorganisms ranging from arsenic to uranium.

However, even at lower levels, those contaminants do pose some risk, Elvrum said. Federal regulators weigh both the health threat and the cost to remove the chemical before setting the accepted limit.

Plus, as new testing methods and technology become available, scientists are finding new chemicals in the water they couldn't detect even 10 years ago.

For the roughly 1.2 million Minnesotans who get their drinking water from a private well, the rules are much less stringent. Some homeowners may not have had their water tested in decades — if ever.

New wells must be tested for arsenic, nitrate and bacteria before they can be used, Elvrum said. However, if one or all of the three are higher than the standard, it's up to the homeowner whether to take action.

About 10 percent of new private wells in Minnesota exceed the arsenic standard, and about 1 percent exceed the standard for nitrate.

That doesn't mean the homeowner can't drink their water, but there could be health risks. Nitrate can cause blue baby syndrome in infants, a potentially fatal condition.

Elvrum advises people with private wells to have their water tested — at least once for arsenic, and every other year for nitrate and bacteria.

— Kirsti Marohn

Do you have the rights to the water beneath your property in Minnesota?

Water tower
Woodbury, Minn., in 2014 made a plan for curbing its increased use of ground water.
Jeffrey Thompson | MPR News file

Answered simply, yes, you do have rights to the water beneath your property.

Minnesota has a riparian system of private water rights, which means that property owners have rights to "reasonable use" of water that borders their property — including ground water.

There are some limits regarding how much water people can draw from the ground, but most landowners won't run into any issues.

Property owners can generally use up to 10,000 gallons of water per day without a permit, according to Tom Hovey of the Department of Natural Resource's water regulation unit. You'd have to run a garden hose all day, nonstop, to hit that amount of water.

Anything more than that and you'll need a permit so the state can regulate usage.

In addition, private water rights are subordinate to the public's rights, Hovey said.

— Cody Nelson

How often do municipal drinking water supplies get tested for lead?

Lead pipes
Lead pipes that used to be in a city water system.
Seth Perlman | AP file

The answer depends on where you live, according to Anna Schliep with the Minnesota Department of Health.

If a public water system is new or recently changed the source of its water, testing is done every six months. For systems that haven't had any problems, it could happen as infrequently as every three years.

Many older homes have lead pipes, which can cause problems if they start to corrode and lead dissolves into the water. So lead testing is done right at the home's drinking water tap, Schliep said. Residents are notified the same day if lead levels exceed 15 parts per billion.

Schliep said Minnesota has safeguards to prevent a scenario like Flint, Michigan. That city switched its source of drinking water from Lake Huron to the Flint River, resulting in lead levels well above federal safety thresholds.

If a city is going to change its source of water or treatment method, the health department would increase lead testing and look at what's being done to prevent pipe corrosion, Schliep said.

Starting next year, Minnesota schools will be required to test for lead contamination at least once every five years.

For homeowners with private wells, it's their responsibility to get their water tested for lead. Schliep recommends every home be tested at least once, and again before a new baby comes home.

There's a simple way to protect yourself from lead. Allow the tap to run until the water is cool or cold before drinking so you get fresh water that hasn't been sitting the pipes.

— Kirsti Marohn

Tell us what you'd like to know about water


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