A Groundwater Extraction

Total Groundwater Extractions (AF)

Water Use Sectors

B Groundwater Extraction Methods

Meters

Electrical Records

Land Use

Groundwater Model

Shasta Watershed Groundwater Model

 Historical groundwater level and stream flow observations were used to calibrate the model which make it a 'Likely' representation of the basins hydrology. However, there is still variation of the model from observations and there are significant data gaps in observations throughout the basin thus we estimate the model accuracy falls in the range of 60-70%.

Other

Population data from (https://gis.water.ca.gov/app/bp-dashboard/final/) to estimate urban water demand

Data source 2010 US Census. Dataset comes from US Census based on input from residents and may not be completed by all residents. Per capita use is based on statewide average which may vary locally.

C Surface Water Supply

Total Surface Water Supply (AF)

Methods Used to Determine

The Scott Valley and Shasta Valley Watermaster District keeps records of surface water supply that are summarized in an annual report for each standard year in March. The report was not available in time this year, but coordination with the SSWD was begun to plan for earlier data sharing of surface water supply for future annual reports.

Water Source Types

D Total Water Use

Water Source Types

Water Use Sectors

E Change in Storage

Method used to calculate change in storage

Change in storage was calculated by taking the difference between the Fall 2021 groundwater contour and the Fall 2020 groundwater contour to estimate change in groundwater levels. This change in groundwater level was then multiplied by the aquifer storage coefficients to estimate change in aquifer storage. However, there are still data gaps in the groundwater level network that impact the accuracy of the groundwater contours thus there is still uncertainty in the calculated change in storage. This is important to note because an erroneous depth to water measurement at one of the monitoring points can estimate a much larger change in groundwater level that in reality and this error is multiplied because that change in groundwater level is used over a large spatial distance due to data gaps in the basin.

F Monitoring Network Module

G PMA Module