Flat Drop Reservoir   Be the first to submit input for Flat Drop Reservoir. If you have info on Flat Drop Reservoir, Valley County, Montana please submit it here to improve this web site.          These outdoors activities are available near Flat Drop Reservoir.   Public Lands Near Flat Drop Reservoir: Hell Creek State Park, Montana, 19 miles away   Marinas On or Near Flat Drop Reservoir: Rock Creek Marina, Fort Peck, 18 miles away