yes ,you need other material.what i did was put rocks down then filled with gravel.keep in mind you need to spread material out 4-6 feet.you cannot pile rocks on top of each other and stop the water,build a rock and gravel dam about 5 ft.i'm holding back water on over 5 acres about 2-4 inches.i do not think you can hold back 3-4 ft. of water but i dont think he's trying to do that.if you hold back 1 ft. of water in a creek that will be plenty of water for animals to stay on the property.