BASIN MANAGEMENT OBJECTIVES VINA SUBINVENTORY UNIT

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1 BASIN MANAGEMENT OBJECTIVES VINA SUBINVENTORY UNIT Butte County Water Advisory Committee Member J. Knight Contact Information Phone Number: Address: Description of the Vina Sub-Inventory Unit The Vina Inventory Unit (IU) covers about 75,000 acres in the northern Sacramento Valley region of Butte County. It is bordered by Tehama County to the north, Big Chico Creek to the south, the Sacramento River to the west, and the foothills to the east. In a normal water year, about 50% of the Vina IU is in summer agricultural production supported by groundwater. Another 10% of the inventory unit is within the Chico Urban Area Sub-inventory Unit (SIU), which uses groundwater for its municipal supply. A separate sub-inventory unit report was developed for the Chico Urban Area. Current Conditions During the past decade, land use changes have included some conversion of rangeland to orchards requiring installation of new wells, replantings of almond and walnut orchards, and conversion or irrigated land from pasture and row crops to new walnut orchards. Management Objective Our objective is to maintain the groundwater surface elevation during the peak summer irrigation season (July and August) in all aquifer systems at a level that will assure an adequate and affordable irrigation groundwater supply. It is the intent of this management objective to assure a sustainable agricultural supply of good quality water now and into the future, and to assure the water supply can be utilized without injuring groundwater quality or inducing land subsidence. The management objective is also to assure a groundwater supply of adequate quality and quantity from all aquifer systems for domestic users in the inventory unit. Vina 2018 BMO 1

2 Geologic Formations Identified In Inventory Unit Geologic formations in the Vina IU from youngest (shallowest) to oldest (deepest) include: Quaternary Alluvium Basin Deposits Modesto Formation Riverbank Formation Tuscan Unit C (Upper Tuscan) Tuscan Unit B (Lower Tuscan) Fresh Water-bearing Units. In the Sacramento Valley Region of Butte County, fresh groundwater-bearing units include, from youngest (shallowest) to oldest (deepest), the Modesto, Riverbank, Laguna, Tehama and Tuscan Formations. Those included in the Vina IU are: Modesto Formation Riverbank Formation Tuscan Unit C (Upper Tuscan) Tuscan Unit B (Lower Tuscan) BMO Key Wells Selected for Groundwater Level Monitoring SPRING Well ID First Aquifer Stage 1 Alert Stage 2 Alert Well Type Record System Elev. (ft) Elev. (ft) 22N01E09B01M 2001 Upper Tuscan Domestic N01E20K01M 1961 Modesto Formation Domestic N01E18A01M 1976 Upper Tuscan Domestic N01E29P02M 1990 Upper Tuscan Domestic N01E33A01M 2001 Lower Tuscan Irrigation N01W10E01M 2001 Lower Tuscan Irrigation N01W10M01M 2001 Upper Tuscan Monitoring N01W27L01M 1976 Modesto Formation Domestic N01W36P01M 1959 Basin Deposits Domestic N02W25C01M 1967 Alluvium Irrigation FALL Well ID First Aquifer Stage 1 Alert Stage 2 Alert Well Type Record System Elev. (ft) Elev. (ft) 22N01E09B01M 2001 Upper Tuscan Domestic N01E20K01M 1961 Modesto Formation Domestic N01E18A01M 1976 Upper Tuscan Domestic N01E29P02M 1990 Upper Tuscan Domestic N01E33A01M 2001 Lower Tuscan Irrigation N01W10E01M 2001 Lower Tuscan Irrigation N01W10M01M 2001 Upper Tuscan Monitoring N01W27L01M 1976 Modesto Formation Domestic N01W36P01M 1959 Basin Deposits Domestic N02W25C01M 1967 Alluvium Irrigation A number of additional wells have been added to the monitoring network in the Vina IU. They are included in the data summary spreadsheets (Appendix) and hydrographs are Vina 2018 BMO 2

3 provided in this report. However, a BMO has not yet been established for these wells since their period of record is not yet long enough for analysis. 23N01W25G001- irrigation well added to the DWR monitoring network in N01W28M multi-completion monitoring wells added in N01W31M multi-completion monitoring wells added in N01W03H002-4 multi-completion monitoring wells added in 2012 BMO Key Well Selected for Groundwater Quality Monitoring Annual Groundwater Quality Measurements State Well Number Water Quality Measurement Temp. ( o C) 23N01E29L003M ph E.C. (µs/cm) Vina 2018 BMO 3

4 BMO Key Well(s) Selected for Land Subsidence Monitoring Land subsidence is continuously monitored by the Department of Water Resources and Butte County Department of Water and Resource Conservation in the closest Sub- Inventory Unit at State Well number 21N01W24B01M, located within the M&T Sub- Inventory Unit. A Sacramento Valley-wide GPS survey was conducted during Results of the survey will be available in 2018 and will provide additional land subsidence data throughout the county. Stakeholder Interaction Stakeholder meetings were held twice during the year 2010 and informally the SIU representative met with stakeholders throughout There has been little participation since Let there be no doubt that there exists no tolerance for transferring groundwater out of this region. Lower groundwater levels have not affected domestic or agricultural water availability given the precipitation we have received in the past few years. There is a general supportive spirit to allow monitoring of groundwater levels and to participate in whatever monitoring efforts that may be put forth. Future Monitoring Recommendations Efforts will be made to identify well characteristics of any domestic wells that could be added to the existing monitoring well network in the inventory unit to allow development of management objectives for the alluvial aquifer system. Stakeholders will work to bring additional wells with sufficient historical data into the water quality monitoring network. Vina SIU Stakeholders Issues and Recommendations The Vina SIU stakeholders are concerned with the following issues specific to the Vina area: 1. Lack of collection area for precipitation: The North Butte/South Tehama area is influenced by the Sierra/Cascade Ridge which is close to the valley and is rarely breached. Much of N.E. California drains north to the Pit River or south to the Vina 2018 BMO 4

5 North Fork of the Feather. Lake Almanor feeds the Feather River, not Deer Creek. 2. Lack of water available for recharge: Cohasset Ridge further exacerbates this situation in that Chico Creek and Butte Creek are diverted south. Creeks in Vina head below 4000 feet and have small catchments with little or no snow pack. Only Deer Creek and Big Chico Creek flow year round. 3. Surface water substitution is not an easy option: The seasonal nature of the streams flowing across the Vina Sub-Inventory Unit means that there is no obvious source for surface water. 4. Northern Butte County is subject to massive development pressure. When unirrigated land is developed to housing or irrigated crops, consumption levels most likely will be increased. The eastern edges of the aquifer would suffer the most impacts from depressurization of the aquifer from unsustainable pumping. Supporting Data Hydrographs on the following pages depict yearly spring and fall groundwater level measurements with established alert levels. QM Questionable Measurement Vina 2018 BMO 5

6 22N01E09B001M Vina 2018 BMO 6

7 22N01E20K001 Vina 2018 BMO 7

8 23N01E18A001M Vina 2018 BMO 8

9 23N01E29P002 Vina 2018 BMO 9

10 23N01E33A001 Vina 2018 BMO 10

11 23N01W10E001 Vina 2018 BMO 11

12 23N01W10M001M *Note no 2012 fall measurement Vina 2018 BMO 12

13 23N01W27L001 Vina 2018 BMO 13

14 23N01W36P001M Vina 2018 BMO 14

15 23N02W25C001M Vina 2018 BMO 15

16 23N02W25G001 *Note all data including summer measurements shown for 25G001 since no alert levels are assigned due to limited period of record. 23N01W28M *Note all data including summer measurements shown for 28M with weekly measurements during summer of Vina 2018 BMO 16

17 Vina 2018 BMO 17

18 23N01W31M *Note: all data including summer measurements shown for 31M with weekly measurements during summer of Vina 2018 BMO 18

19 Vina 2018 BMO 19

20 23N01W03H002-4 *Note: all data including summer measurements shown for 03H Vina 2018 BMO 20

21 Vina 2018 BMO 21

22 23N01W09E001M Although not a designated BMO well, 23N01W09E001M has long been a Key Well highlighted in the Butte Basin Water Users Annual Report and therefore it is included. This well is located in the northern Vina sub-area. The area surrounding this well is characterized by rural, agricultural land use supported by groundwater. This well is an irrigation well, constructed in the confined portion of the aquifer system, with a groundwater level measurement record dating back to The groundwater levels in this well were monitored on a semi-annual basis until the mid-1970s, on a monthly basis from the mid-1970s to Levels are typically monitored four times a year during March, July, August and October but during , levels were monitored monthly April through October due to drought conditions. The figure shows a seasonal fluctuation (spring to fall) in groundwater levels of about 5 to 15 feet during years of normal precipitation and drought. Long-term comparison of spring-to-spring groundwater levels shows a decline of approximately 30 feet associated with the and approximately 10 to 12 feet associated with the and 1994 drought periods drought period. Overall comparison of spring to spring groundwater levels associated with this confined portion of the aquifer system indicates that there has not been much change in the spring groundwater levels since the late 1940 s through In the last four years of severe drought, levels have fallen about 4 10 feet and fall levels are about 12 feet lower than in the 1960s. Vina 2018 BMO 22