GSP Annual Report
5-022.05 CHOWCHILLA
2022 (OCT. 2021 - SEP. 2022)
Single Annual Report
GSP Annual Report Information Comments
03/31/2023 3:29 PM
2022 (OCT. 2021 - SEP. 2022)
Single Annual Report
A Groundwater Extraction
Total Groundwater Extractions (AF)
409,060
Water Use Sectors
9,360
0
399,700
0
0
0
0
B Groundwater Extraction Methods
Meters
37,370
Direct
5-10 %
Meter data includes: (1) Groundwater wells operated by the City of Chowchilla for urban water use. Potable water demand in the City of Chowchilla is currently met exclusively through groundwater, which is pumped directly into the distribution system to meet demands in the Urban Water Use Sector. The remaining rural residential and domestic water demand is estimated based on an urban lands water balance. (2) Groundwater wells operated by certain landowners in TTWD GSA who are parties to the Subsidence Control Measures Agreement. A portion of agricultural water demand in areas managed by those landowners is met through groundwater pumping, and is metered and reported under the provisions of the Subsidence Control Measures Agreement.
Estimated based on the typical field accuracy of meters, and the combined accuracy of volumes in the City of Chowchilla system (accounting for metered groundwater, metered deliveries, unmetered deliveries, and apparent losses).
Electrical Records
0
Land Use
371,690
Estimate
20-30 %
Calculated as the closure of a Land Surface System water budget for the Chowchilla Subbasin (closure of each water use sector was calculated separately for each subregion, accounting for measured pumping). All other Land Surface System water budget components were quantified using measured volumes (where available) or using unitized IWFM Demand Calculator (IDC) model results multiplied by land use areas. Land use data was developed from Land IQ data, crop reports, and County Agriculture Commission land use data.
Typical uncertainty when calculated for Land Surface System water balance closure. Uncertainty of the water budget closure is calculated as the combined uncertainty of all other water budget flow paths following the procedure described by Clemmens and Burt (1997), as discussed in the Annual Report. The uncertainties of all other flow paths are quantified based on measurement device accuracy, technical literature, or professional judgment.
Groundwater Model
0
Other
0
C Surface Water Supply
Total Surface Water Supply (AF)
36,200
Methods Used to Determine
CVP Supplies and Local Supplies: Calculated as the difference between Surface Water Inflows and Surface Water Outflows, by water source type (at this time, surface water reuse is not a significant source of supply in the Plan area). This assumes that the Surface Water Supply that is "used or available for use" includes all water that is diverted, infiltrated, or evaporated from waterways in the Plan area. Surface Water Inflows and Surface Water Outflows in the Plan area were directly measured (where a recorder or streamflow measurement station is available) or estimated through a waterway balance based on available records of diversions and spillage, and estimates of seepage, evaporation, and runoff (using waterway attributes from GIS analyses and NRCS soils data, and runoff calculated in an IWFM Demand Calculator (IDC) model). Local Imported Supplies: TTWD records of purchased water (approx. 1,400 AF in WY 2022)
Water Source Types
34,800
0
0
0
1,400
0
0
0
D Total Water Use
Total Water Use (AF)
465,880
Methods Used to Determine
Total Water Use is assumed to be the total volume of water that is applied to land surfaces or that precipitates onto land surfaces. A portion of this water is consumptively "used" through evapotranspiration/evaporation. The remaining water is "used" to recharge the Subbasin through deep percolation and seepage of runoff.
Groundwater is determined following the methods described in Part B.
Surface water is determined from delivery records (from Districts) and riparian diversion reports (eWRIMS).
Precipitation is determined from PRISM data.
Water Source Types
409,060
21,740
0
0
35,080
Precipitation
Water Use Sectors
11,900
0
451,540
0
1,060
1,380
0
E Change in Storage
Method used to calculate change in storage
Annual change in groundwater storage was calculated from the groundwater elevation contour maps based on the difference in spring-to-spring groundwater elevation for each of the principal aquifers (Upper and Lower Aquifers). Both confined and unconfined groundwater conditions occur within the Subbasin. Outside of the delineated confined area, changes in groundwater levels (in both the Upper and Lower Aquifers) were multiplied by representative specific yield values to estimate change in groundwater storage. Within the delineated area of confinement in the Lower Aquifer, groundwater potentiometric surface changes in the Lower Aquifer were multiplied by a much smaller storage coefficient value to calculate annual changes in groundwater storage in the Lower Aquifer. The specific yield and storage coefficient values used in the analysis are derived from values in the calibrated integrated groundwater flow model (MCSim) developed and applied during the preparation of the GSP.
