GSP Annual Report
9-007.01 UPPER SAN LUIS REY VALLEY
2021 (OCT. 2020 - SEP. 2021)
Single Annual Report
GSP Annual Report Information Comments
03/30/2022 11:43 AM
2021 (OCT. 2020 - SEP. 2021)
Single Annual Report
A Groundwater Extraction
Total Groundwater Extractions (AF)
14,002
Water Use Sectors
1,623
0
10,253
0
0
2,126
0
B Groundwater Extraction Methods
Meters
2,947
Direct
Other
Reported values from individual users or water agencies. Based on unknown meter types.
Accuracy unknown
Electrical Records
0
Land Use
0
Groundwater Model
6,384
Estimate
5-10 %
MODFLOW-NWT groundwater flow model. Model estimated agricultural water demand from land use, crop type mapping, and agricultural water demand factors from Table 3-6 of the County?s General Plan Update Groundwater Study (2010). Estimated pumping was then adjusted during model calibration. WY2021 estimated agricultural pumping for non-reported pumping used the relationship between model-estimated pumping from the calibration period 1990 through 2020 and recorded precipitation at nearby weather gages. "Extractions" from native vegetation represented by model-calculated ET term in groundwater budget. This term for WY2021 was assumed to be the average of the last 5 years of model-calculated values.
Calibration relative error of 8.4%. Note: calibration based on limited data in areas of the subbasin.
Other
4,673
Estimate
Other
Water use in tribal areas based on previously published estimates, water use for entities that submitted pumping data prior to WY2021 but not for WY2021 was estimated based on prior data.
Accuracy unknown
C Surface Water Supply
Total Surface Water Supply (AF)
6,017
Methods Used to Determine
Reported imported water deliveries (note: imported water from SWP or Colorado River Project not differentiated) for WY2021 and reported surface water diversions from previous years correlated with precipitaiton at nearby weather station
Water Source Types
0
5,611
0
406
0
0
0
0
D Total Water Use
Total Water Use (AF)
0
Methods Used to Determine
Based on reported pumping, imported water use, and surface water diversion data. Estimated based on ET and modeled agricultural pumping based on land use, crop type, and crop demand published by San Diego County, estimated from previously published estimates of water use on tribal lands, estimated from previously reported pumping volumes. Individual assumptions provided in Groundwater Extraction Methods and Surface Water Supply upload fields.
Water Source Types
14,002
6,017
0
0
0
Water Use Sectors
2,184
0
15,663
0
0
2,126
46
Surface water spreading in catchment basin
E Change in Storage
Method used to calculate change in storage
Change in groundwater storage was estimated for WY 2021 using the water level contours developed for Fall 2020 and Fall 2021 (spatially interpolated between water level contours) and aquifer parameters values from the calibrated groundwater flow model. The change in groundwater storage (in acre-ft) was calculated for each model cell using the following equation: Change in Groundwater Storage = (WL2021 ? WL2020) x SY x A, where WL2021 = Groundwater elevation from fall 2021, WL2020 = Groundwater elevation from fall 2020, SY = Specific yield of model cell from calibrated groundwater model, and A = Model cell area. The individual changes in groundwater storage were then summed over the model area for the entire USLR Valley Groundwater Subbasin.
