What are some ways to measure the "Gallon s Per Minute" of a creek?

Question

I am trying to figure the amount of water that passes through our creek in a given minute.

Answer 1

You could take some measurements, such as rate of flow or pressure of the water downstream, and measure it against the size of the creek at the point you are measuring. (width and depth) Also, consider that the amount changes from day to day in most cases, as indicated by the change in depth, usually caused by rain (or thaw, in spring) along the tributaries/drainage leading to the creek.

Answer 2

throw something in the water to measure how fast the water is moving. Figure out the cross-sectional area of the creek; multiply the length across by the depth. Now multiply the speed by the area and this will give you a volume flow rate. convert gallons per minute.

NOTE:
The speed of the water is not uniform. The center of the creek will flow faster than the edges. Same goes for top and bottom.