A woman in Methuen, Massachusetts discovered a dead reptile on the banks of the river and mistook it for an alligator.
Deborah Salerno and her husband were reportedly exploring a new boat ramp on Methuen's Merrimack River when Salerno saw a scaled creature floating in the water, according to Boston.com.
Initially Salerno believed the creature to be an alligator, which frightened and caused her to call the police, The Eagle Tribune reports.
"Then I noticed in the water, a floating dead alligator. I called the police. I didn't know who to contact because I never heard of an alligator in the Merrimack."
Salerno said that she became more convinced the creature was an alligator when her husband mentioned to her that a caiman - a gator-like reptile - was spotted on the streets of a nearby Massachusetts town earlier in the summer.
Further investigation revealed that the creature was actually not an alligator, but a black-and-white Argentine tegu. The large lizard is legal to own as a pet in Massachusetts.
The police did not remove the tegu from the water upon arrival, and Salerno expressed concern before finding out that the creature was not actually an alligator.
"I said, do you think there's more?" She was worried, since "two alligators in New England" seemed like "too much of a coincidence."
She said she felt less concerned after finding out that the creature was a tegu.
"I had thought it was an alligator and I felt lost because no one was trying to help me, no one was taking it seriously."