You'd have a hard time drowning in the Coachella canal. It is a welcome relief to take a dip when it's hot but unless the agent had a heart attack, I'm thinking foul play. And not necessarily from illegals.
Niland is roughly fifty miles from the border. Temperatures regularly surpass 110 degrees in the summer. It is a hot spot (literally) for "coyotes." It's very desolate and there is a huge Marine Corps aerial gunnery range that borders the East side of the Coachella canal.
Sadly you find dead illegals (always young or old)because smugglers abandoned them. They're in the middle of nowhere and they have no idea where to go. This is usually preceded by robbery and sometimes rape.
One summer we found a teenage girl who had been abandoned. She was suffering from heat stroke. Unfortunately our medical personell couldn't save her.
Prayers and sympathy for this agent's family.
Thanks for the interesting post.