How Safe Are NH's Lakes, Beaches And Rivers For Swimming And Boating

NEW HAMPSHIRE — With summer kicking off, many New Hampshire families are planning getaways to lakes and rivers for swimming, paddling and fishing.

But is it safe to dip your toe in the water in New Hampshire?

There’s no simple answer. But there are resources New Hampshire residents should check before heading out to the beach or launching a kayak or canoe in a river.

For starters, check with the New Hampshire Department of Environmental Service's Beach Inspection Program for beach closing and other notices about water quality.

Currently, there are cyanobacteria warnings at Pine River Pond, Webster Lake, Bow Lake, and Lake Kanasatka and cyanobacteria alerts at Lake Wentworth, Eastman Pond, Mascoma Lake, and Lake Umbagog, according to the state's Healthy Swimming Mapper.

Next, consult the Environmental Protection Agency’s inventory of impaired waterways. New Hampshire is part of a six-state region with 5,254 bodies of water that exceed the “total maximum daily load,” or TMDL, standards set forth in the Clean Water Act.

What does that mean?

The term relates to the amount of nitrogen and phosphorus pollution in freshwaters. The nutrients are essential for plant growth, but an overabundance of them causes algae to grow faster than ecosystems can handle, harming water quality and decreasing the oxygen fish and other aquatic life need to survive.

Common sources of excess nitrate that reach lakes and streams include septic systems, animal feedlots, agricultural fertilizers, manure, industrial waste waters, sanitary landfills, and garbage dumps. At elevated levels, nitrates can cause severe illnesses in infants and domestic animals.

Algae blooms also allow so-called “rough fish” — carp and bullhead — populations to increase at the expense of game fish populations. Severe algae blooms result in stinky, unattractive lake water, undesirable for swimming, boating or fishing.

Nitrates added to the soil in agricultural states contribute to the infamous Gulf of Mexico “dead zone,” where fish and aquatic life can no longer survive. Freshwater is less dense than the saline seawater, so the nitrogen and phosphorus-laden runoff sits on top of the ocean surface and doesn’t mix, spurring an overgrowth of algae that consumes oxygen as the plants decompose.

The low-oxygen waters create the condition called hypoxia, and marine life suffocates and dies. These waters are warmer than the deeper ocean water, further contributing to the stratification. When the waters don’t mix, oxygen in the bottom waters is limited.

If your favorite swimming hole isn’t posted as closed, you may want to test it yourself for E. coli bacteria to calculate the swimming risk. County health departments can often help residents test freshwater bodies for bacteria or nitrates. Help finding a state-certified lab is available at the EPA’s Safe Drinking Water Hotline at 800-426-4791 or online.

How Safe Are Rivers?

America’s rivers aren’t the playground for canoers and kayakers they once were. The EPA estimates that 44 percent of U.S. waterways are too polluted for swimming or fishing.

As a result, “freshwater species are going extinct faster than ocean or land species, and rivers are among the most threatened ecosystems on the planet,” America’s Rivers said with the release earlier this year of its America’s 10 Most Endangered Rivers report.

Topping the list is the Colorado River at the Grand Canyon, one of the Seven Natural Wonders of the World and a vacation destination favorite for many Americans.

Others on that list, ranked according to the level of endangerment, include:

• The Ohio River, which winds through parts of Pennsylvania, Ohio, West Virginia, Kentucky, Indiana and Illinois;
• The Pearl River in Mississippi;
• The Snake River as it flows through Idaho, Oregon and Washington;
• The Clark Fork River in Montana;
• The Eel River in California;
• The Lehigh River in Pennsylvania;
• The Chilkat and Klehini rivers in Alaska;
• The Rio Gallinas River in New Mexico; and
• The Okefenokee Swamp in Georgia and Florida.

Placement on the list doesn’t automatically mean those rivers shouldn’t be used for recreation, but it underscores the threats to rivers by climate change, pollution, dams and other uses, according to American Rivers.

Brain-Eating Amoeba: Should You Worry?

One other thing to be aware of if you're swimming in a freshwater lake, especially in warmer climates as summer and during the late summer months: The Centers for Disease Control and Prevention says that swimmers in freshwater lakes should assume that the organism Naegleria fowleri better known as brain-eating amoeba are present, although actual cases of infection are extremely rare.

How rare? In New Hampshire, zero cases of brain-eating amoeba were reported from 1962 to 2022.

• Related: Brain-Eating Amoeba: Assume There’s A Risk In Warm Waters, CDC Says

Though rare, Naegleria fowleri illnesses are fatal 97 percent of the time, with only four known survivors among 157 known infected individuals since surveillance began in the 1960s, according to the CDC.

The organism is most often found in warm, Southern states, but a warming climate increases the likelihood of encountering the organism farther north.

Other swimming-related illnesses, including skin, ear, respiratory, eye, and other infections — can be caused by germs that naturally live in the water and soil.

One other thing to be aware of if you're swimming in a freshwater lake, especially in warmer climates: The Centers for Disease Control and Prevention says that swimmers in freshwater lakes should assume brain-eating amoeba are present, although actual cases of infection are extremely rare.

• Related: Brain-Eating Amoeba: Assume There’s A Risk In Warm Waters, CDC Says

The organism is most often found in warm, Southern states, but a warming climate increases the likelihood of encountering the organism farther north.

The CDC estimates about 7.2 million people get sick with waterborne diseases every year, though the agency said it can’t say how many infections stem from freshwater exposure versus drinking water exposure.