MINNEAPOLIS — Up to 60 percent of the groundwater monitoring wells sampled across a swath of central and eastern Minnesota are contaminated with nitrates well above the safe drinking water standard, the Minnesota Pollution Control Agency said Thursday in a report that highlights growing concerns about the state’s drinkingwater.

Some of the affected cities include Becker, Clear Lake, Cold Spring, Hastings, Goodhue, Adrian and Park Rapids, the report said. They lie in a region of shallow sand and gravel aquifers. A 2014 report from the Minnesota Department of Health estimated the treatment costs statewide were in the billions of dollars, including $9 million for Hastings and $11 million for Park Rapids.

Nitrate contamination can lead to illnesses such as “blue baby syndrome,” a fatal blood disorder for infants. The chemicals can enter groundwater from sources such as animal manure and agricultural fertilizers. The safe level for drinking water is considered 10 milligrams per liter.

Many smaller communities are spending millions of dollars to address the problem, the MPCA report said. Their options have including distributing bottled water, drilling new wells and building new treatment plants.