Sky Lake by Scott Lipanovich

Perusing a local newspaper, Jeff Taylor reads about the death of a famous water skier, Brett Boyd, who lived at an exclusive high-country enclave known as Sky Lake. Brett and Jeff were close childhood friends but they hadn’t communicated in years. Jeff didn’t even know his old friend lived in the area. 
In a kind of pilgrimage, Jeff drives to secluded Sky Lake and locates Brett’s cabin. A man with a gun arrives in a battery-powered cart and tells Jeff to get lost. Thus begins Jeff’s suspicions about the death of his high school friend. Within a month, three other water skiers are killed. Jeff devotes himself to catching the murderer. Along the way, he tangles with the darkness that resides beneath the region’s glorious facade.