Determining Groundwater Use
There are two basic ways to determine the amount of groundwater used by each landowner: (1) measuring the volume of groundwater pumped by using a flowmeter on the well, or (2) through crop evapotranspiration information obtained via satellite technology. A flowmeter installed on a well measures the gross or total amount of groundwater pumped, whereas the net amount of consumed groundwater can be determined through calculations using crop water use data. The gross amount of water pumped will exceed the net consumptive use because of inefficiencies in the irrigation system.
The North Fork Kings Groundwater Sustainability Agency (NFKGSA) has recently hired a consultant that utilizes satellite data, cropping data, and local weather stations within the NFKGSA to calculate, by field and by parcel, the amount of water consumed by the crop each month. The actual cropped acreage of a field is identified along with the crop itself. This data is available approximately 30 days after the end of each month. After accounting for surface water deliveries to the field and the amount of precipitation used by the crop, the amount of consumed groundwater can be obtained. At this time, the NFKGSA is using the crop consumptive use information to calculate groundwater use and is only requiring flowmeters to be installed on new wells, but all groundwater wells within the GSA may be required to measure groundwater extraction by flowmeters at some point in the future.
The maps below represent the amount of water consumed by fields in the GSA for the months June, July, and August 2021. Measuring water consumption and calculating groundwater use allows the NFKGSA Board to effectively track progress and make management decisions to achieve groundwater sustainability as required by State law. These maps that allow you to view your measured water use are located at www.northforkkings.org/maps. Additional information on how the crop consumptive use information will be used will be provided to all landowners in the near future.