The Lil River Rats and the Adventure of the Lost Treasure(2003)

Overview:

Nine-year-old Molly Brown lived and breathed "that river." After her mother died it was just her and her dad, Paul, and of course "cappy" her ailing grandfather, but with all cappy’s medical bills, Paul’s only choice is to sell everything, including the family home, and move away. But Molly can't leave her friends and the river, especially the river... it’s been her whole life! She has to make a plan!