GSP Annual Report
1-005 SCOTT RIVER VALLEY
2021 (OCT. 2020 - SEP. 2021)
Single Annual Report
GSP Annual Report Information Comments
03/30/2022 2:24 PM
2021 (OCT. 2020 - SEP. 2021)
Single Annual Report
A Groundwater Extraction
Total Groundwater Extractions (AF)
40,000
Water Use Sectors
1,000
0
39,000
0
0
0
0
B Groundwater Extraction Methods
Meters
0
Electrical Records
0
Land Use
0
Groundwater Model
40,000
Estimate
60-70 %
Estimated values are based on the current soil water budget model used by the UC Davis Scott Valley Intergrated Hydrologic Model and the soil water budget model published by Foglia et al., 2013a,b, available at http://groundwater.ucdavis.edu/Research/ScottValley/
Accuracy based on uncertainty in inputs and model uncertainty.
Other
1,000
Estimate
Other
Urban groundwater extraction is estimated as 1,000 acre-feet, calculated based ond a Scott Valley population of 3,520 people (per the 2019 Basin prioritization).
Accuracy dependant on the accuracy of the population and accuracy of the estimated water use per person used to calculate urban groundwater exraction.
C Surface Water Supply
Total Surface Water Supply (AF)
26,000
Methods Used to Determine
The middle valueis used from ithe range of estimated surface water use values (24,000 - 28,000 AF), which represent the entire Scott Valley groundwater basin (DWR Basin 1-5). These values are based on the estimated average annual surface water irrigation amount in 1991-2011. The range is based on the current calibration of the soil water budget model used by the UC Davis Scott Valley Intergrated Hydrologic Model, and includes the estimtate from the soil water budget model published by Foglia et al., 2013a,b, available at http://groundwater.ucdavis.edu/Research/ScottValley/. A drought emergency curtailment order went into effect by mid-September 2021, but is not have throught to reduce the amount of surface water use significantly compared to the full allocation of previous years.
Water Source Types
0
0
0
26,000
0
0
0
0
D Total Water Use
Total Water Use (AF)
66,000
Methods Used to Determine
Sum of surface and groundwater use.
Water Source Types
40,000
26,000
0
0
0
Water Use Sectors
1,000
0
39,000
0
0
0
26,000
Surface water use is not divided into water use sectors and is estimated as a total value.
E Change in Storage
Method used to calculate change in storage
In the private monitoring well network (10 wells), water levels measured in March of 2021 were, on average, 2.5 feet lower than during the same period in 2020 indicating an overall decrease in groundwater storage (see water level report at http://groundwater.ucdavis.edu/Research/ScottValley/). In DWR's Water Data Library, six wells have water levels documented for both, spring 2020 and spring 2021. Between spring 2019 and spring 2020, water levels in these six wells increased by 2.2 feet, on average, with only one well having lower water levels in 2021, when compared to 2020 (https://sgma.water.ca.gov/webgis/?appid=SGMADataViewer#gwlevels; accessed February 9, 2022). The current UC Davis Scott Valley Integrated Hydrologic Model (https://doi.org/10.1029/2018WR024209) was used to determine the relationship between water levels at the original 32 locations of the private monitoring well network and total groundwater storage in the Scott Valley aquifer, which extends over approximately 50,000 acres of alluvium, for the period from 10/1/1990 to 9/30/2011. Based on simulated annual change in storage and simulated water levels at the location of the original 32 private monitoring wells, it was estimated that the average total annual groundwater storage change is between 3 thousand and 5 thousand acre-feet for each one foot change in average water levels in the monitoring well network during January through March. The statistical uncertainty of the estimated storage change of -10,000 acft is +/-2.5 thousand acre-feet.
