This parking area is known by locals as The Willows due to the impressive willow trees which line the waterway.
One of the best places in Griffith to camp if you're travelling with a caravan or sleeping in a vehicle. The location has a waste dumping station, toilets, free BBQ's, and waterfront overnight camping among the Willow trees. It's popular with caravaners and even nicer than some other paid locations around the area.
The large man made waterway is part of the massive Murrumbidgee Irrigation Area (MIA) system, which supplies water to the food-bowl of Australia.
The cache is a micro and should be pretty easy to find. Plenty of parking for a park and grab, but watch out for muggles!