These fish migrate upstream to spawn and need an adequate amount of water to allow for migration. Local areas of dewatered streams can cut off miles of potential spawning habitat. Many local agricultural producers recognize the need to improve streamflows to maintain a sustainable agriculture business and a viable community. This water balance was recommended as a way to better understand the hydrology of the basin. A water balance is really an accounting system of the hydrology of a basin.
Hydrology is the collection, occurrence, and distribution of water.
In order to develop a water balance, all of the inputs and outputs of water in a watershed need to be identified and the data gathered. These parameters are sufficient for an annual water balance. However, for a monthly or seasonal water balance, changes in soil moisture and groundwater storage are also necessary to capture the deficit of water in the summer and the excess in the winter. Precipitation and streamflow are directly measurable and can be spatially interpolated with some confidence. However, evapotranspiration requires crop information, air temperature, relative humidity, and soil moisture.