Open channel flow measurement is important due to decreasing water supplies and growing concerns regarding municipal water measurement. These flows need to be metered to minimize the margin of error. The Parshall flume in some cases is the standard measurement device for open channels but a true standard device is one which has been accurately calibrated, correctly installed, and sufficiently maintained to fulfill the original requirements. Primary Flow Signal developed the PFS-HPF which is tested by a third party and has a certifiable discharge coefficient. The precision of the PFS-HPF is +/-2.0% of max rate and the primary device can be used with of secondary read-out devices. Unlike the traditional Parshall flume, the PFS-HPF is designed so that the appropriate placement of secondary measurement devices is recognizable and verifiable. Accurate flow measurement for open channels is important. With laboratory flow calibration, HPF accuracy is +/-1.0% of max rate with a much lower headloss compared to the Parshall flume. Due to the reduction of available water, combined with the importance for metering the fluid flow of sewage and other open channel flows, accuracy must be taken into consideration to select a solution.