Another inexpensive method to try:

Some people call them gabion structures or wire baskets. To assemble these structures first buy some hardware wire or woven wire at farm/ranch supply store. Bend the wire into a square or rectangulr basket (with the top piece missing). Fill the basket with various size rocks and then place a wire top on the basket. Use hog rings to complete the assembly process. Size of basket may vary, but 4'X 8'X 1 ft. deep are common. Storms will generally not wash this device down the creek. You may need to build several in place to get the desired results. As you already pointed out, this (homemade )structure will leak also. Just lay some impervious fabric, rubber liner or even bentonite on the front slope and cover with topsoil. This should grass in eventually. The completed structure is quite inexpensive, durable and workable.

Get ahold of me through my email if you have questions.
good luck,

Ed