A number of people were at the lake about 25 miles west of Yakima on Saturday when the woman attempted to retrieve a floatation device that had drifted into the lake and the boy offered to help.
Witnesses said the boy panicked and struggled with the woman, exhausting them both.
Witnesses pulled her from the water, but she could not be revived.
Sheriff's divers found the teen's body two hours later, about 25 feet from shore in 10 feet of water. He also was declared dead at the scene.
The county coroner identified him as Cristian A. Sanchez and the woman as Josefina Guerrero, both of Yakima.
Information from: Yakima Herald-Republic, http://www.yakimaherald.com
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