Abstract: At 3:45 p.m. on June 25, 2021, Employee #1, a Fire Fighter I employed by Cal Fire since August 2019, responded with Engine 1173 to a vegetation fire in Redwood Valley. He and a coworker conducted a hose lay operation on a hillside with a slight incline and performed mop-up operations until approximately 5:30 p.m. After completing mop-up and returning to the engine, Employee #1 began experiencing symptoms of heat-related illness, including dizziness and muscle cramps. He was taken to the emergency department at Adventist Health in Ukiah, where he was treated for mild dehydration with IV fluids and released. The employee was treated without hospitalization. The peak temperature on the day of the incident was 98 degrees Fahrenheit at approximately 2:16 p.m.