The mission of many public and private water resources organizations is to manage and conserve existing water supplies. These management efforts involve making sound technical and economic decisions concerning new and existing water needs, while respecting the environment by sustaining or restoring the aquatic ecosystems which may be affected. One key to better management practices, including water conservation, is reliable and accurate water measurement. The term "water measurement" as used in this manual refers to the measurement of flow (unit volume per unit time). Major advances in measurement technology along with a continued demand for the Water Measurement Manual are responsible for initiating this revision.