California's drought dried up a lake so much that it revealed a crashed plane, possibly solving a decades-old mystery

• California's drought made it possible to get sonar images of a plane at the bottom of a lake.
• Officials believe it may be the plane from a mid-air crash that killed 4 people in 1965.
• California declared a drought emergency as the state's lakes drop to historically low levels.

California officials believe that drought conditions may have led them to the remains of a plane that crash-landed in a lake, according to local reports.

Folsom Lake, in the state's Sierra Nevada foothills, is the site of a mid-air crash on New Year's Day 1965 that downed a plane and killed four people, according to court records.

A long-term drought - worsened in June by a brutal heatwave across the southwestern US - has lowered the level of California's lakes enough that sonar images of a downed plane can be detected for the first time, CBS 13 reported.

That plane's propeller and tail match the description of a Piper Comanche 250 that got into the mid-air collision with another plane in 1965, the channel reported.

Speaking of the discovery, Tyler Atkinson of Marine surveyors Seafloor Systems told CBS13 that he was out at the lake with his colleague Jeff Riley and "saw something that was not right."

Riley said to the network: "These lights on the [a remotely operated vehicle] allow me to say, 'OK there is no way that's a rock.'"

Folsom Lake is experiencing historically low levels of water, and is currently at 37% capacity, according to the San Francisco Chronicle. This allowed the surveyors to take sonar images of the plane's tail and propeller for the first time.

On May 10, California Gov. Gavin Newsom declared a drought emergency in 41 counties, covering 30% of the state's population.

Placer County Sheriff's Office is still to decide whether or not to investigate and attempt to recover the plane, CBS13 reported.

After the crash in 1965, the pilot of the other plane managed to right the aircraft after dropping 1,500 feet.

The plane made it back to the airfield, according to the San Francisco Chronicle. The bodies of three of those killed in the other plane were never found, CBS13 reported.

Frank Wilcox, the brother of one of the crash victims, never stopped looking for his brother's body, but died two years ago, CBS13 reported.