Nothing is more elegant and simple than a Parshall Flume. The concrete or sheet metal devices, when properly built, measure how much water flows through a ditch. While water courts adjudicate, it is Parshall Flumes that actually measure out the water. Unfortunately, they're unlikely to do an accurate job. According to Colorado State University, only 39 out of 149 flumes an academic team examined in Colorado were in good condition, and most of those were less than 10 years old. Because of settling, but also due to corrosion, holes and vegetation, some flumes were as much as 30 percent off. The obvious cure is to tear out the offending flume, stabilize the ground, and put in a new one. But Steven Abt, the civil engineering professor who led the study, has developed a computer program that allows landowners to correct water-flow measurements without replacing the flume. For information about the Parshall Flume Discharge Correction Program, contact Professor Abt, Civil Engineering, A227 Engineering Research Center, Colorado State University, Fort Collins, CO 80523 (970/491-8203).