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HomeMy WebLinkAboutBC Water Advisory Committee and Technical Advisory Committee's Agenda Packet - Nov. 20, 2017 Menchaca, Clarissa From: BCWater Sent: Monday, November 20, 2017 12*36 PIVI To: BCWater Subject: Water Advisory Committee and Technical Advisory Committee agenda Packet for November 30, 2017 The following are available on the Butte County Water and Resource Conservation website: Water Advisory Committee Packet Technical Advisory Committee Packet You can access the documents by clicking on the corresponding hyperlink. If you are unable to access the information please feel free to contact our department. Thank you, Butte-ounty Water and Resource Conservation Administrative Anal),st,Associate 308 Nelson Ave.,Oro,ville,CA 95965 Office:5301552 35-9.4,Fax:530.538.3807 "COUNTY OF BUTTE E-MAIL DISCLAIMER: This e-mail and any attachment thereto may contain private,confidential,and privileged material for the sole use of the intended recipient. Any review,copying,or distribution of this e-mail(or any attachments thereto)by other than the County of Butte or the intended recipient is strictly prohibited. If you are NOT the intended recipient,please contact the sender immediately and permonently delete the original and any copies of this e-mail and any attachments thereto. Water and Resource Conservation Paul Gosselin, Director 3018 Nelson Avenue T: 5301.538.4343 buttecounty.net/waterresourceconservatiori Oroville, California 95965 F: 5307.538.38017 bcwaterCbuttecounty.net '01AIE9&.RE:5a:1'RCE.C:C3N5EkVAWN BUTTE COUNTY WATER ADVISORY COMMITTEE I'v`IEETING ®ATI: Thursday„ Novembei,30, 2017 TIME 2:OOPM. PLACE: Tahoe Room 702 Mira Loma Oroville, CA 95965 Water Advisory Committee Agenda Items I. Introductions and WAC Roll Call 2. *Approval of minutes for the April 27, 2017 meeting(Chair Heringer) 3. *Sub-inventory unit reports from WAC members on 2017 and current conditions (Chair I leringer) 4. Update on activities related to the Sustainable Groundwater Management Act(Staff, Water and Resource Conservation) a. General Status b. Agricultural Groundwater Users of Butte County c. Groundwater Pumpers Advisory Committee 5. 20117 BMOs and Groundwater Status Report(Christina Buck, Water and Resource Conservation) a. *Important dates in 2018 6. WAC Updates (Christina.Buck, Water and Resource Conservation) a. New appointments, reappointments, & vacancies 7. Departmental Updates (Paul Gosselin, Water and Resource Conservation) 8. WAC members wishing to address items not listed on the agenda. (The Water Advisory Committee is prohibited by state law from taking action on any item presented if it is not listed on the agenda). 9. Public Comment: Any person wanting to address the Water Advisory Committee on any item NOT ON TODAY'S AGENDA may do so at this time. The Water Advisory Committee will not be making decisions or determinations on items brought up during Public Comment. 10. Future Meeting date and location: April 26, 2018. location TBD 11. Adjournment * Indicates attached items WAC Item 2 MINUTES OF THE BUTTE COUNTY WATER COMMISSION WATER ADVISORY COMMITTEE April 27, 2017 Feather River Tribal Health 2145 5"'Avenue Oroville, CA 95965 1. Introductions and WAC Roll Call. WAC members present: Sub-unit representatives present: Catherine Cottle, Angel Slough; Eugene Massa, Biggs- West Gridley; JP Stover, Butte Sink; Gary Cole, Cherokee; Fred Montgomery, Durham- Dayton; Rick Ponciano, Esquon; Charlie Edgar, Llano Seco; Lee Heringer, M&T; Toni Ruggle, North Yuba; Chris Fleindell, Thermalito; Anjanette Shadley, Western Canal; James "Bo" Sheppard, Municipal at-large-Biggs; Linda Draper, Municipal at-large- Oroville; John Scott, Watershed at-large-Cherokee; Sharon Wallace, Watershed at-large- Big Chico Creek; Loretta Torres, Watershed at-large-Little Chico Creek; Samantha Lewis, Agriculture at-large. Sub-unit representatives absent: Mark Orme, Butte; Gene Harris, Richvale; J Knight, Vina; Karl Ory, Municipal at-large- Chico; Mike Zuccolillo, Municipal at-large-Paradise; Chuck Kutz, Watershed at-large- Butte Creek; Larry Lloyd, Foothill./Mountain-at-large. Sub-units vacant: Chico Urban Area, Pentz, Municipal at-large-Gridley, Environmental at-large. We had a quorurn. 2. Election of Chair and Vice Chair. Motion by Charlie Edgar to elect Lee Heringer as Chair and Catherine Cottle as Vice Chair. Second by Rick Ponciano. Motion carried 17-0-0. 3. Approval of minutes for the April 28, 2016 meeting. Motion by Anjanette Shadley, second by Rick Ponciano to approve the minutes for April 28, 2016 as presented. Motion carried 17-0-0. 4. Sustainable Groundwater Management Act Update. Paul Gosselin provided an overview of the status of the Groundwater Sustainability Agencies in each groundwater subbasin and the status of efforts to remove the overlap. He also described the formation of the Groundwater Pumpers Advisory Committee. This new Brown Act committee meets regularly the 3d Monday of the month at the CSU Farm at 8:30 am. Vickie Newlin provided an update on the status of GSAs submitting letters of support to the County indicating their intent to work together on Groundwater Sustainability Planning efforts and to support a future grant application to help fund those efforts. 5. Water Year Conditions a. Hydrologic Conditions Christina Buck provided an overview of water year conditions with regards to the Sacramento Valley 8-station index, runoff, snowpack, statewide and Lake Oroville reservoir storage, and statewide conditions as of April 1. b. Surface water allocations Vickie Newlin stated that State Water Project Contractors currently have an allocation of 85%and the North of Delta CVP allocation is 100% 6. Sub-inventory unit reports from WAC members on current conditions Each member had an opportunity to comment. Eugene Massa described how much water remains in their drains because of the wet winter. Chris Heindell indicated that Thermalito ID has increased their groundwater level monitoring because of the increased use of their wells for water supply due to impacts of the Oroville Spillway incident. Anjanette Shadley reported that Western Canal has been monitoring groundwater levels in wells since 1994 and they remain relatively stable with some exceptions in wells on the perimeter of the district. Toni Ruggle indicated that Cal Water Oroville operations were also impacted by the Oroville Spillway incident but well levels remain healthy in their production wells. Catherine Cottle described the flooding that occurred in Angel Slough due to the wet winter. Fred Montgomery indicated that irrigation has not yet been needed but may be coming soon with the forecasted warm weather to come. Charlie Edgar reported that they lost 100 feet of bank on the Sacramento River this winter. Lee Heringer echoed the occurrence of significant bank erosion in their area and requested that 2016 spring measurements for wells 21 NO 1 W 11 A002 and 21 NO I W 11 A003 be considered questionable measurements because of their unusually high value. Christina Buck indicated that a number of shallow wells in the monitoring network had unusually high levels in Spring 2016 which is likely related to the timing of that measurement and conditions in the Sacramento River and local streams at that time. Sharon Wallace commented on the potential benefits to salmon of Big Chico Creek of this wet winter. 7. WAC Updates Christina went over new appointments, reappointments & current vacancies 8. WAC members wishing to address items not listed_on the agenda. None. 9. Public Comment: None. 10. Future meeting date and location: November 30, 2017 Location TSD. 11. Adjournment. VVAC Bern 3 Sub Inventory Unit Report on BMO Alert Stages Please complete the form and return to: Butte County Department of Water and Resource Conservation 308, Nelson Avenue Oroville, CA 95965 (530) 538-4343 BCWater@buttecounty.net Reported by: (Print Name) Sub Inventory Unit (SIU): 1. Do you wish to, revisit your chosen methodology for defining BMO alert stages in your SIU? If so, why? 2. Are wells in your SIU currently at an Alert Stage? If so, how many wells and at what stage? 3. Describe any major land use changes you are aware of that may impact groundwater levels. 4. Describe any notable conservation efforts or water management changes that could affect groundwater levels andl/or describe any efforts to address issues that may have contributed to reaching an Alert Stage. 5. Describe the extent of interactions with stakeholders in your or the surrounding SlUs 6. Have any abnormal well functions been reported in your or the surrounding SlUs? 7. Final comments or concerns. Submitted for review by the Butte County Water Commission Technical Advisory Committee. Please sign form below for inclusion in your BMO report. Reported by: (Signature) Date: WAC Itri 5a Basin Management Objective Program Important Dates for 2018 Posted November 2017 December 2017—Review and provide input on the 2017 Groundwater Status Repoli and BMOs for 2018 December 29, 2017—Final date to submit comments on draft BMO reports Week of January 8,2018—TAC meeting to review the Groundwater Status Report February 7,2018—Groundwater Status Report presented to the Butte County Water Commission February 27,2018—Groundwater Status Report presented to the Butte County Board of Supervisors March 2018—Spring groundwater elevation measurements by DWR April 26,2018—WAc/,rAC meeting to review spring groundwater elevation data/BMOs July 2018—Summer groundwater elevation measurements August 2018—Annual groundwater quality meaSUrernents Summer groundwater elevation measurements October 2018—Fall groundwater elevation measurements by DR November 29, 2018—WAC/TAC meeting to review fall groundwater elevation data and water quality data. 2018 Water Advisory Committee Meeting Dates Thursday April 26, 2018 at 2:00 PM Thursday November 29, 2018 at 2:00 PM „O,j%! Water and Resource Conservation Paul Gosselin, Director 308 Nelson Avenue T: 530.538.4343 buttecounty.net/waterresourceconservation Oroville, California 95965 F: 530.5,38.3807 bcwater@buttecounty.net BUTTE COUNTY TECHNICAL ADVISORY COMMITTEE MEETING DATE: 1"hursday, November 30, 2017 TIME: hmmediately following the WAC Meeting PLACE: Tahoe Room 202 Mira Loma Oroville, CA Technical Advisory Committee Agenda Items 1. Introductions and TAC Roll Call 2. *Approval of minutes for the April 27, 2017 meeting (Chair Cannell) 3. Review and comment on 2017. monitoring and BMOs a. *Groundwater levels b. *Water quality trend monitoring results 4. Update on special projects (Staff, Water and Resource Conservation) a. *Interbasin Groundwater Clow Evaluation Project b. *Stable Isotope Recharge Study c. Evaluation of Restoration and Recharge Potential within Groundwater Basins of Butte County d. *Groundwater Sustainability Grant. 5. TAC members wishing to address items not listed on the agenda. (The Technical Advisory Committee is prohibited by state law from taking action on any itern presented if it is not listed on the agenda). G. Public Comment: Any person wanting to address the Technical Advisory Committee on any item NOT ON TODAY'S AGENDA may do so at this time. The Technical Advisory Committee will not be making decisions or determinations on items brought up during Public Comment. 7. Future Meeting date and location: January 2018 TBD 8. Adjournment. * Indicates attached items TAC I tern 2 MINUTES OF THE BUTTE COUNTY WATER COMMISSION TECHNICAL ADVISORY COMMITTEE April 27, 2017 Feather River Tribal Health 2145 5 1h Avenue Oroville, CA 95965 1 Introductions and Roll Call TAC members present. Chair Joe Connell, Pete Bonacich, Ian Tietz, Todd Greene, Debbie Spangler, Richard Price and Amanda Aguiar TAC mernbers absent: none 2. Approval Of Minutes for the November 17, 2016 meeting Motion by Pete Bonacich, second by Debbie Spangler to approve the minutes for November 17, 2016 with corrections as noted by Paul Gosselin. Motion carried 7-0-0. 3. Update on Well Permit Applications. Amanda Aguiar provided information on well permit applications that were compiled by the Division of Environmental Health. Connell mentioned that it would be helpful to have information on the number of wells actually drilled rather than permit application numbers. Amanda stated that it could be possible in the future but the current database does not provide those numbers. 4. Review and comment on Spring 2017 groundwater level measurements and BMQs Christina Buck provided an overview of the data and described the charts included in the TAC packet. TAC discussed the data. 5. Update on Special Projects. Vickie Newlin provided an update on the status of the Stressed Basins grant Recharge project. The project should be completed by the end of the calendar year. Christina Buck described the status of the Butte Basin Groundwater Model. It is currently undergoing calibration since its updates from the Water Inventory and Analysis project that concluded in 2016. Christina reported that the Interbasin Groundwater Flow Evaluation Project is wrapping up with a presentation of the draft report to the NSV TAC on May 17"' and to the NSV Board on June 5"', 2017. The Stable Isotope Recharge Study is also wrapping up with data collection completed and analysis and report writing beginning. Results and the prqject report will be coming out this summer. 6. TAC members wishing to address items not listed on the agenda. Members discussed the need for frost protection in Almonds in late February. 7. Public Comment: Any person wanting to address the Technical Advisory Committee on any item NOT ON TODAY'S AGENDA may do so at this time. The Technical Advisory Committee will not be making decisions or determinations on items brought up during Public Comment. None. 8. Future Meeting date and location:November 30, 2017 Location TBD 9. Adjournment * Indicates attached items 'TAC 11tem 3a 13 BUTTE COUNTY Program 4 VINA CHICO,, RB�N DURHAMd DAYTON MST 4 PENTZ DURHAM/ l DAYTON F ANGEL E SQUON + SLOU(G�Fi r' > O (Do CHEROKEE,/ � LLANO � SCO1 h ky � WEST"ERN(CANAL r Legend 0 Fall 2017 ,alert Stage i '1,kERMALITo Monitored, No BMC) RICHVALE Alert not reached Alert 1 Alert 2 NORTH YUBA 0 Quest. Meas. 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SIU 109 Average GWL Change 3 Median GWL Change 3, 89 Average Increase 4 Median Increase 4 Max Increase 12 Vina 20 Averaqa Decrease -2 Median Decrease -1 1 Max Decrease -11 Butte Sin **Questionable Measurements not included .......... 20 01 Average Change in WSE Note: +value indicates in rased W E E Lowerbound of Range value indicates decreased WSE 15 ............. ................. I Upperbound of Range 10 --------------- g, 5 ................ 9. 0.2 (// ..._.. r __ ..../ �j.. 0 1 T I -1.2 -0.5 -5 ------- .... ................................ ............... .. .................. -10 -15 .......... (3) -C 7E 0 0 (1) C C Qj 4.5 W �Erao -- U W 4- co C W, o) 0 0 Q) 00 -2 U CL D aj 0 LU 41-j CC CO V) E a) 0 D c 0 :E U Figure 1.Minim uni,average„arra maximum Fall 20,16 to Fail 2017 ch onge in Water Surface Eleva tion(WSE)in each sub-region with average clearage labeled. .... 18 160 m_. Average NST Cl P, 140 IN M in DTW r 12 _._ _.._ _.... Max DTW 100 01111- m 43 l 1 f 17 20 i l p 2Lk Ig L III . sm otic_.. 0 T T T TT I.. T. G -194 m -2w cu Q u> QJ ..... ._. ... a) - CO U CL u C C E W q— ees i� Rgure 2,Foli 2017 Average,Minimum,and fwt'ox�ira urn Depth to,1 oter(d.d71M)l in each sub-region with overoge DTW lobeled, TAC Item 3b Water and Resource Conservation Paul Gosselin, Director rr�rr r 308 Nelson Avenue T: 530.538.4343 buttecounty.net/waterresourceconservation .. CJroville, California 95965 F: 530.538.3807 bcwvater@buttecounty.net WAIER&RESOURCE CONSERVAXY4 INTERDEPARTMENTAL. MEMORANDUM TO: Butte County Water Commission Technical Advisory Committee FROM: Christina Buck,Water Resources Scientist SUBJECT: 2017 Groundwater Quality Trend Monitoring Update DATE: August 18,2017 INTRODUCTION AND BACKGROUND The Butte County Department of Water and Resource Conservation (DW&RC) conducted its sixteenth year of groundwater quality trend monitoring within the county July 24-27 and August 3, 2017.. As required by Chapter 33A, the parameters monitored were temperature, pH, and electrical conductivity(EC).These parameters are the basic water quality characteristics needed to evaluate a basin for evidence of saline intrusion.The groundwater quality trend monitoring serves to establish baseline levels for these parameters throughout the county so that any future changes can be identified and further investigation and/or monitoring can subsequently be developed. In 2017, all samples fell within the acceptable range of water quality values set forth by State and Federal agencies and alert stages defined in Chapter 33A. METHODOLOGY AND RESULTS In 2013, DW&RC purchased a Hach HQd portable meter with a pH and conductivity probe. This was the fifth yearthis meter was used to do the groundwater quality testing. The sites visited in Butte County are on private land and many of the wells are used for agricultural purposes(irrigating orchards, rice, or pasture). However,the two Thermalito wells,Chico Urban Area well,Vina well, and the Llano Seco well provide domestic water supply.The sampling grid spans from north of the Chico Urban Area (Viva sub-inventory unit),west towards the Sacramento River(Llano Seco and M&T sub-inventory units), east towards the foothills(Pentz sub-inventory unit), and south towards Gridley(Biggs-West Gridley sub-inventory unit). Figure 1 shows the approximate locations (township, range, and section)of the water quality wells in relation to wells monitored four times per year for groundwater level in the Basin Management Objectives Program. As in previous years,we are fortunate to have support and permission from local property owners who coordinate timing of sampling and allow access to their wells.We have provided them with the preliminary results from this year's monitoring. Twelve of the thirteen wells in the network were sampled this year. The Western Canal (West)well was inaccessible due to changes to the irrigation system that made it impossible to sample. It is expected that sampling at this location will resume next year. Following standard sampling procedure, a water sample is pulled from a discharge location at or near the well and values for temperature, pH and EC are recorded when the pH reading from the water sample stabilizes.Temperature is a standard parameter measured when assessing water quality, mostly to indicate that water being sampled is representative of aquifer water and not water standing in the well itself. The US Environmental Protection Agency(US EPA)establishes drinking water quality standards using two categories, Primary Standards and Secondary Standards'. Primary Standards are based on health considerations and Secondary Standards are based on taste,odor, color,corrosivity,foaming, and staining properties of water. Secondary water quality thresholds for pH and EC compared to the range of 2017 values are presented in Table 1. Table 1. US EPA Secondary Standards for measured parameters ................... j Parameter Secondary Standard or Rangeof Secondary WO Threshold 2017 Values Notes re: Butte County Results ..... . 'pH __..._ 6.5 to 8.5 ' 7.0-7.7 Within range of secondary water quality thresholds. Electrical < 900 PS/cm—drinking water Within range of secondary water quality 3Conductivity(EC) < 700 SIS/cm—ag water 136-498 ;thresholds. Water quality data for specific wells is presented in tables and graphs on the following pages. Temperature is an important parameter because it affects chemical reactions that may occur in groundwater. Also, considerable changes in temperature could be an indication of other source waters migrating into the aquifer system such as stream seepage or flow from a different aquifer system. To date,temperature has been relatively consistent in all wells. Chapter 33A states that"the BMO Alert Stage for temperature will be reached when the measurement is more than five(5)degrees outside of the historic range of measurements."The 2017 measurements were all within 1.0°C of the average temperature for each well. The 16 year temperature range for all wells is less than 5°C(Table 3).The lowest temperature reading was in the M&T well(17.2°C)and the high was in the Pentz well (21.6°C). Measurements for pH remained relatively stable compared to previous years (see attached graphs). The highest pH was found in the Llano Seco well (7.7)and the lowest in the Chico Urban Area and Western Canal (East)(7.0). All measurements for pH were well within the secondary water quality thresholds of 6.5-8.5(Table 1,Table 4 and included graphs). Electrical conductivity(EC) measures the ability of a solution to conduct an electrical current due to the presence of ions. Observed readings for electrical conductivity can have a large range, up to 447µS/cm at a particular well (Western Canal-west),yet 2017 measurements were all well within the secondary water quality thresholds established by State and Federal regulatory agencies(Table 1,Table 6,and included graphs).The highest EC measurement was from the M&T well (498 pS/cm) and the lowest was from the Thermalito well(136µS/cm). CONCLUSIONS This was the sixteenth season the DW&RC collected groundwater quality information. Overall,the resu Its of the water quality sampling indicate no significant changes in groundwater quality with respect to temperature, pH, or electrical conductivity. The greatest change compared to 2016 EC levels occurred in the M&T well. This well has one of the largest ranges of observed EC levels over the period of record. When sampling this well this year,it was observed that the EC level dropped with subsequent samples even after the pH level had stabilized. It is possible this well takes longer to stabilize than the standard minimum 15 minutes that is allowed to purge the well before a sample is taken. Staff recommends that next year,this well be sampled with EC measurements recorded from start of the pump until EC levels stabilize to establish the minimum run time needed for this well to be monitored consistently. It is possible that the large range in observed EC values in this well is due to varying lengths of time the pump was running from I.http://www.epa.-gov/safewater/consumer/2ndstandards.html 2 year to year before a sample was taken. This topic can be further discussed with the TAC at their upcoming meeting in November. Water quality parameters have naturally occurring variability,so year to year changes are expected and nothing in this year's measurements gives cause for concern or immediate further investigation or analysis. Further investigation would be advisable if values were to fall outside of the acceptable range. The focus of this trend monitoring program is to evaluate the basin for evidence of saline intrusion. No major shifts occurred in the EC measurements in the sampled wells and the basin appears to be free of saline intrusion. This data continues to help establish baseline levels for these parameters across the county so that any future changes in water quality can be evaluated and further investigation and/or monitoring can be developed. Further information on water quality standards for different constituents can be found at www.swrcb.ca.gov or in the Compilation of Water Quality Goals, published by the State Water Resources Control Board. 3 Figure 1.Approximate well locations for waiter quality wells in relation to wells monitored annually(four times)for water level. BUTTE COUNTY Basin Management Objective Water Quality, rend Monitoring Grid oe VIVA '61"'CHIC OURBiN— _ FOOTJ$LL DURHAM/ DAYTON 0 PENTZ ""'ek DURHAM!/ DAYTON ANGEL ESQli SLOUGH 0 EROK�E/j LLANO SJECO NO WESTERN CANAL QiWM S' Leggin BMO Groundwater Level Wells 241 Water Quality-Well Name ERMALITO ................ Biggs-West Gridley _44 " R, 61,'0 Cherokee 06 Chico Urban Area Durham IDayton 41P Esquoin ORTH YUBA 0 Llano Seco 0 M &T BIGGS- W Perak EST GRIDLEY 40 0 Pentz-Butte Valley i ild TTE Therri Thermalito domestic Vino BUTTE SINK Mj Western Canal (east) 0 1 2 4 6 8 Western Canal(west) Mile Updated 2014 4 DATA TABLES AND GRAPHS Table 2.Annual groundwater temperature(IQ Sub-Inventory Unit 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 Biggs-West Gridley 18.5 _18.5 18.1 20.5 18.2 18.3 _18.7 _.19.0 19.2 20.1 18.0 18.4 19.0 18.5 18.4 18,6 Cherokee 22.4 21.9 21.2 21.4 21.1 20.7 21.0 20.9 21,9 21.8 21.8 21.3 21.9 21.2 20.8 21.2 Chico Urban Area 18.4 20 8.8 19.5 21.6 18.0 NM 18A 17.8 1 18.2 1 19.0 Durham Dayton 18.8 19.9 21.8 20.4 17.4 NM 19.3 NM 18.9 18.0 NM 18.5 19.1 18.1 18.0 18.8 Esquon 19.7 18.9 19.6 1 20,1 1 20.7 19,0 19,6 19.0 19.1 20.0 21.4 18.1 20.2 18.9 18.0 19.1 Llano Seco 20.8 20.6 20.7 20.6 21.7 20.4 23.5 19.9 20.0 19.9 II."j.,,--I :'��� ., ;I M&T 17,6 18.2 17.8 19,2 18.6 18.0 I7.7 18,6 I7.8 NM 18.3 17.9 NM 17.1 17.2 17.2 Pentz22.2 21.5 21.3 21.5 23.9 21.9 21.9 21.9 21.5 21.5 21.6 777. .Pentz-Butte Valley 27.0 26.4 26.7 23,2 Thermalito 18.3 17.9 17.1 17.1 18.4 17.7 18.9 17.6 NM NM 17.8 17.3 17.5 17.3 17.4 17.5 Thermalito domestic -� �%'. �:, . 19.4 19.4 19.4 NM NM 19.8 NM 19.9 19.8 20.0 Vina 19,6 20,3 19.2 19.2 19.6 18.9 19.6 18.9 18.8 22.8 18.8 20.2 21.4 19.5 19.8 19.5 Western Canal(East) 18.4 18.2 19.9 20.5 18.8 18.6 19.1 19.0 18.8 19.0 NM 18.3 18.9 18.5 19.1 18-6 -- 1 1 1 Western Canal(West)j 19,0 1 18.1 197 8T 20,8718.5 20.6 2 .8 18.5T is, 1 20.5 20.1 19.1 20.2 18.6 18.8 NM *Pentz-Butte Valley well discontinued in 2006 Table 3.Groundwater temperature average and range over 16 year sampling period (OC) Sub4nventory Unit Average Range Biggs-West Gridley 18.8 2.5 Cherokee 21.4 1.7 Chico Urban Area 19.0 3.8 Durham Dayton 19.0 4.4 Esquon 19.5 3.4 Llano Seco 20.8 3.6 M &T 17.9 2.1 Pentz 21.9 2.6 *Pentz-Butte Valley 25.8 3.8 Thermalito 17.7 1.8 Thermalito domestic 19.7 0.6 Vina 19.8 4.0 Western Canal (East) 18.9 2.3 Western Canal (West) 19.6 3.7 Table 4.Annual groundwater pH Sub-inventory Unit 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011] 2012 2013 2014 2015 2016 2017 Biggs-West Gridley 7.6 7,5 7,5 TO 7.6 7.6 7.7 7.9 7.9 7.2 7.9 7.9 7.1 7.6 7.6 7.7 Cherokee 7.5 7.5 7.1 7.4 7.4 7.3 7.3 7.3 7.2 7.6 7.3 7,3 6,9 7.2 7.2 7.1 Chico Urban Area 6.9 6.9 6.9 7.0 7.5 7.3 7.1 NM 6.9 To 7.0 Durham Dayton 7.7 7.2 7.6 7.6 7.5 NM 7.5 NM 7.4 7.7 NM 7.5 NM 7.5 7.5 7.3 Esquon 7.3 7.5 7.1 7.4 7.5 7.4 7.2 7.4 7.4 7.6 1 7.2 7.3 5.9 7.4 7.2 7.3 Llano Seco 7.9 8.1 82 8.1 7.9 8,0 7.0 7,8 7.8 7.7 M&T 7.2. . .,..7.5:__ .27.5 6.9 7.8 7.9 7.6 7.7 7.6 7.6 NM 7.2 7.9 NM 7.4 7.7 7.6 : Pentz : �M 7-6 :1,`11�-,,-,11'1��,, "I�'"�9*'I, "I'l�ll""I'�"--",".,"�"I'�,�"-l",� --", 7.4 7.5 7.4 7.3 7.8 7.5 6.7 7.0 7.4 7.2 *Pentz-Butte Valley 7.1 6,9 7.3 6-2 f T", Thermalito 7.0 6.5 7.1 7.1 7.9 7.4 7.4 7.4 NM NM 8.0 7.7 7,5 7,1 7.1 7.1 Thermalito domestic - `, 7.7 7.8 7.7 NM NIM 7.8 NM 6.9 7.6 7.6 2 Vina 7.5 7.6 6,9 6,2 7.7 7.5 7.5 7.4 7.6 8.0 7.3 7.8 1 7.9 7.1 7.4 7.3 Western Canal(East) 1 7.0 1 6,6 6,8 6.9 7.3 6.9 7.0 7.0 1 7.11 70 NM 7.2 1 6.5 7.1 7.0 7.0 Westem Canal{West)l 7.8 1 B.1 7.1 1 6.9 1 7.9 1 7.9 1 7.8 1 6.6 1 7.8 7.5 7.7 7.5 1 7.1 7.5 7.4 NM Table S.Groundwater pH average and range over 16 year sampling period Sub-Inventory Unit Average Range Biggs-West Gridley 7.6 0.9 Cherokee 7.3 0.7 Chico Urban Area 7.0 0.7 Durham Dayton 7.5 0.5 Esquon 7.3 1.6 Llano Seco 7.9 1.1 M&T 7.6 1.0 Pentz 7.3 1.1 *Pentz-Butte Valley 6.9 1.1 Thermalito 7.3 1.5 Thermalito domestic 7.6 1.0 Vina 7.4 1.8 Western Canal (East) 7.0 0.8 Western Canal (West) 7.5 1.5 Table 6. Annual groundwater Electrical Conductivity(VS/cm) Sub-inventory Unit 2002 2003 2004 2006 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 Biggs-West Gridley 346 370 323 361 351 382 354 331 343 320 300 291 326 288 296 290 Cherokee 222 232 215 266 242 267 268 243 270 275 245 260 330 255 261 284 T Chico Urban Area 280 291 260 249 250 248 217 NM 214 221 254 Durham Dayton 315 348 259 340 322 NM 327 NM 307 315 NM 298 304 322 316 322 Esquon 388 526 470 557 507 480 439 419 427 415 408 512 443 417 499 416 Llano Seco 204 195 196 198 192 184 240 180 182 179 M&T 418 551 678 504 465 451 667 445 592 NM 427 391 NM 362 333 498 Pentz 28 1 229 227 225 224 204 204 231 210 204 207 *Pentz-Butte Valley 195 186 211 240 Thermalito 132 164 149 150 152 242 205 158 NM NM 292 179 181 136 159 136 374 350 354 N 327 Thermalito domestic I"`,",�,, " '. M NM 342 NM 320 324 ...... ......... Vina 197 225 180 216 192 224 203 200 199 194 174 1 188 201 200 186 161 Western Canal(East) 447 344 400 524 492 471 482 488 465 459 NM 447 1 442 449 444 441 Western Canal(West)l 464 1 248 407 501 309 477 469 462 455 460 630 629 695 428 581 NM Table 7.Groundwater EC(p5/cm)average and range over 16 year sampling period Sub-inventory Unit Average Range Biggs-West Gridley 330 94 Cherokee 258 115 Chico Urban Area 248 77 Durham Dayton 315 89 Esquon 458 169 Llano Seco 195 61 M&T 484 345 Pentz 217 27 Ventz-Butte Valley 208 54 Thermalito 174 160 Thermalito domestic 342 54 Vina 197 51 Western Canal(East) 453 180 1 Western Canal (West) 481 447 7 Annual Electrical Conductivity (pS/cm) andl pH for each water quality sampling well. The red dashed line indicates the preferred maximum level for EC and the black dashed lines bound the acceptable pH range, 6.5-8.5. Therefore, when the red plot of EC values is below the red dashed line (as it always is), then measured EC is within the secondary standard for agricultural water(<700), which is more restrictive than for drinking water(<900). To be within the acceptable pH ranee, the a line should be within the black dashed lines. Biggs-West Gridley 720, 9.0 620 pH=8,5 — — — — — — — — — — — — — 815 Z 520 810 420 7.5 2 M 320: all, 7.0 5 pH=6, 220 — — — — — — — — — — — — — — 6.5 120 - 6 O 2000 2005 2010 2015 2020 Year q EC 0' PH Cherokee 720 9.0 �z 620 pH=81.51— — --- — — — — — — — — — 8.5 520 8.0 420 �320 7.0 220 . . . . . . . 6,5 120 610 2000 2005 2010 2015 20211 Year .-M-EC 0 PH Chico Urban Area 720 9,0 EC=700°--;--------------,---------- 620 pH=8,5of — — — — — — — — — — — —.— 8.5 520 8.0 420 7.5 320 7.0 220 PH=E,.l — — --- — — — — U 6.5 120 6.0 2000 2005 2010 2015 2020 Year EC --o—pH 8 Durham'Dayton 720 9.0 EC=700------ ------ -- ...,W...�. 620 .....,..._.._ _ ..y..,.,,.. ... 8.5 520 8.0 C 420 -�► .. .. .. . ..._, 7.5 rxi � � I u 320 ._ ... . w w .. -jpa 7.0 a 220 PH=6 5 6,5 120 ....... . . .......... 6.0 2000 2005 2010 2015 2020 Year . r-EC -*-pH Esgu,on 720 _ 9.0, EC=790----------- ,--------------- tin 620 PH=8'7 _ - - - _ _ _ _ _ - - 8,5 8.0 y 520 75 420 __ 7.0 0 _ 6.5 u 320 PH=6.5 6.0 w 220 120 b.a 2000 2005 2010 2015 2020 Year & EC SPH w............. . ._......,...w..,.... _. Clam Sear 72a _ EC=7003,0 .��.�.�..�.���.�.�...��,��®.�"���_,�� 620 . pI-8,5 520 &0 L 420 7.5 3 320 7,0 220 PH 5_ . _ — ,,,,, ,,,. 6.5 120 6.0 2000 2005 2010 2015 2020 Year - -EC -O—PH NOTE:The red dashed line indicates the preferred maximum level for EC and the black dashed lines bound the acceptable pH range,6.5-8.5. Therefore,when the red plot of EC values is below the red dashed line (as it always is), then measured EC is within the secondary standard for agricultural water(K700),which is more restrictive than for drinking water(<900), To be within the acceptable phi range,the black line should be within the black dashed lines. 9 M&T 720 9.0 pH 8.5 620 ............. ,,.... .. �..� � i _. �.,.,�.�....Y..,,........ ,,,. .. $.5 520 :..................... E.0 � 420 II '...... I � 7.5 320 _.....tl. .. 7.0 i LU 220 pl'7101 6.5 120 6.0 2000 2005 2010 2015 2020 Year .-M-EC -*-pH ... ..... . ... . ........................................... Pent2 720 9.0 I 620 8.5 *� 520 Pentz Well 8.0 a 29J03 Butte valley 420 7.5 Well-26 Ol M 320 yl 7.0 220 p 6 .�a.; CMIt� �: �� � — 65 tllti� 120 6.0 2000 2005 2010 2015 2020 Year -w-EC —p—pH Thermalito i 721 9.0 1 ur 620 pH=% ..._— — — — —_— — — — 8.5 ZI 520 8.0 421 7.5 CL 320 7.0 ,C 220 pH'-6' — 6,5 120 w A 6.0 2000 2005 2010 2015 2020 Year EC —s-pH I No,rCz The red dashed line indicates the preferred maximum level for EC and the black dashed lines bound the acceptable pH range,6.5-8.5. Therefore,when the red plot of EC values is below the red dashed line(as it always is),then measured EC is within the secondary standard for agricultural water(<700),which is more restrictive than for drinking water(<000). To be within the acceptable pH range,the black line should be within the black dashed lines. 10 Vilna 720 9.0 v 620 pH=8.5 - 8.5 x 520 _ - - 8.0 � l 420 7.5 ca � u 320 7.0 220 pH'=61 5.5 120 6.0 2000 2005 2010 2015 2020 Year -M--EC -*-pH Western Canal(East) 720 9.0 i620 pH=9.5 _ - --_- - _ - 8.5 520 8.0 420 7.5 u u 320 7.0 220 .pH=6,1 ... .., . ... ...,......�. .... _...- . .� . 6.5 120 6.0 2000 2005 2010 2015 2020 Year �EC �pH Western Canal(West) 720 9.0 pH=8.5 uM 620 - --- - - - -. .. .._. 8.5 520 - 8.0 q 420 - - - _ 7.5 f u ..HM in 20117 2 320 __ 7,0 if220 PH=6. .. .. .. - -_- - - ,. 6.5 120 _ 6.0 2000 2005 2410 2015 2020 Year n._EC -o-.pH., _.........._ NOTE. The red dashed line indicates the preferred maximum level for EC and the black dashed lines bound the acceptable pH range,6.5-6.5. Therefore,when the red plot of EC values is below the red dashed line(as it always is),then measured EC is within the secondary standard for agricultural water(<700),which is more restrictive than for drinking water(<900). To be within the acceptable pH range,the black line should be within the black dashed lines. 11 TAC Stern •a Since many subbasins are hydrologically connected to ad- recharge, irrigation, and changes in climate could change joining subbasins, sustainable groundwater management aquifer conditions and therefore also the interbasin flow will require accounting for groundwater interactions be- rates. Understanding and quantifying these dynamics in the tween adjoining subbasins. For example, groundwater region's Groundwater Sustainability Plans (GSPs) will be an pumping in one subbasin can result in a groundwater de- important component of successfully implementing the pression which causes surrounding groundwater to flow Sustainable Groundwater Management Act (SGMA) in the towards the pumping area. This dynamic can affect inter- northern Sacramento Valley region, basin flow to the subbasin. Other processes such as artificial rr midwater oriels will be a Part of Our Future The complexity of processes affecting interbasin groundwa- desirable Results defined by SGMA will require accounting ter flows make groundwater models effective and neces- for a complete surface water and groundwater budget and sary tools for quantifying these flows. Local investment has the ability to evaluate the effects of changes in the water been made in technical tools such as surface layer models budget (i.e. increased pumping or increased recharge) on (accounting for agricultural and urban water use) and other groundwater conditions over time. Water budgets must water budget approaches. While these are valuable plan- account for interbasin flows and groundwater-surface wa- ning and operations tools for local agencies, they typically ter interaction. Since groundwater modeling will be a part do not calculate interbasin flows or groundwater-surface of our future under SGMA, it will be key to leverage local water interaction and are generally not well suited for pre- data sets and knowledge to improve existing groundwater dictve simulation. SGMA does not legally require the use of models or to develop new ones.. a groundwater model, Yet, successfully avoiding the 6 Un- Undesirable Results Significant orad Unreosonoblo lowering Reduction Seawater Degraded [and Surface Water 6iy levels of Storage Intrusion Quality Subsidence Depletion " a1 I A water budget takes into account the storage crud movement of water be //i ° ,/'%'i'a ° ,w ��✓i a� �, � � � � tween the four,physical systems of the hydralogic cycle: the extmospheric sys " �� t ri -°, i 1 ', r% terry the land surface system the river and str�arrr system and the groundwa /` , "' 'f � 1 ter system. It is on accounting of the total groundwater and surface water en- tering n tering and leaving a basin or other user-defined area over a defined period of time(DWA;r Water Budgets BMP 2015). r � A model is any computational method that represents an approximation of the hydrologic system. While models are by definition, a simplification oa more i ita itif complex reality, they have proven to be useful tools over several decodes for addressing a range of groundwater monage ent challenges and supporting the decision-making process. Models can be useful tools for estimating the po- tential o tential hydrologic effects of proposed water management activities ("DDR Modeling BMP.201 ). In a numerical groundwat r-surface water model, data and parameters are specified-foraccounting units that make up a<model grid. Groundwater and surface water processes are simulated at this scale. A model organizes and incorporates available data from a wide variety of sources and presents ap- Example o 'a modelr°id for proaches to quantify the major flow paths. With a calibrated model (i.e. re- sults simulate historical data reasonably well), scenarios representing changes numericalgroundwater moidel, in water demands, land use changes,or recharge projects can be run to under- ri,r~ rrtrt north of the rrttr fts under- stand the possible range of system responses to changes in processes, 111 Existing Tools and Model Selection The northern Sacramento Valley project area is covered by three regional models i'ncludiing, "Special thtrrrks to the two Central Valley-wide models: 1) C2VSim developed by the Department of 'Water Re- 1'echnicul Collaborators sources (D'WR), and 2) CVIHM developed by the United States Geological Survey (USGS). ur�whro, eraert�rterd these o,arare�ac�crC.irara. These models are both undergoing significant updates. Another regional,Sacramento Valley -wide model is currently being developed by DWR called SVSim. Local groundwater models For the full Report,or.t, also exist. Examples include models currently being updated or developed by Butte and Yu!- Assessment u!- A e ent of ba Counties. None of the existing regional or local groundwater modeles were specifically de- Interconnected veloped for SGIUTA. The regional models were developed prior to SGMA for other purposes ubba in , and list of and assuch, they have limitations, yet also provide opportunities. Although they provide a Technical valuable starting point, they have significant differences in both approach to simulating hy- ,ollaborators visit: drological processes and contain inputs developed from different data sources. This results https:// in significant differences in water budget results in some cases and differing results in simu- �Vww l�ruttecounty'net lating groundwater level conditions. waterresOU,rcecon serva tion/S ecialPr-ojects/ Given these differences, agencies should consider the following question when considering Inter basinGroundwater, which groundwater model to use for GSR development: How well sloes the model match my FlowProject. current understanding of the land surface layer and groundwater budgets in my area? This question can be answered by considering the quality and amount of data, supply and de- Butte County mand, boundary conditions, water budget results, and calibration, including whether aquifer Department of Water parameters are realistic. Since there is not an obvious choice of one of the regional models Resource for the northern Sacramento Valley, each subbasin should compare the model inputs and Conservation results to locally available historical data, if possible.An existing surface layer model or other water budget datasets should be used only to assist in selecting the appropriate groundwa- * Paul Gosselin, Director ter model. It is not appropriate to mix output from the groundwater model with other local Vicide Newlin, water budget sources. Groundwater model results should be presented in full to keep the AsAs �rstant Director,. rst:ina Buck,Waterresults internally consistent. In addition, simulated groundwater elevations near the bounda- Resource Scientist ries have the most effect on quantifying interbasin groundwater flows.Therefore, evaluating Autum Thomas, a model's representation of groundwater levels in comparison to historical data is important, Administrative Analyst particularly in the areas along subbasin boundaries. Cooperation and Uncertainty The most critical factor to address interbasin conditions will not come from a pure technical remedy, but rather from cooperation. Early cooperation with neighboring subbasins to com- pare interbasin flow estimates is very important. Although the exact values may be different, the interbasin flow magnitude and direction should be similar, The differences in part reflect the uncertainty in the modeled systems. WATER&er RCE,CO SERVARON As knowledge of the system and data improves, models are updated to better represent the system. A long term commitment is needed to develop these tools to help us better under- stand the dynamics of the groundwater system. As a result„ promising management actions can more effectively be identified to solve problems and achieve sustainability. The existing w000Rp tools may provide a reasonable starting point but local knowledge and data will make them ,,aw 5, J.�,v,ov,os m &CUP^CRAN better. GSRs should address how they would anticipate and incorporate model updates or new models into resource management. Inevitably, updates or new models will generate Natlional Experience. cocas Fiscus. different results to some degree.The key is to allow for incorporation of the new information a.., __. without resulting in sudden and disruptive shifts in management actions. In the end, the rv' model is a tool to achieve objectives based on real data. Proper planning can allow for using W A TE R the best available science while maintaining a groundwater management structure that is F( Ir N DA "r. ION not destabilized by changes in the model and its results. The ode possible thrr k9h the Water Foundation ndation "rr•am, 'tire Resources Legacy Farad 'TAC Rem 4b t i' Prepared for County of Butte WATER RESOURCE MMERVATION September 30, 2317 HNAL REPORT Stable Isotope Recharge Study Fminal Report, 11" r � r y r �" N P. P ......................... �3 1i �;r:;, ',u„ ;�,,, r/ .:, / ,�/'.�/��//��P�/i /J//ill/„✓///i✓/1��,�,,,,, ri,;,,,�/,;I'i '�, //j�//��✓ l���l��lr,/f (/�/o,', .� '. rr� 1, ��1� �: ;'�r � /-�f'!%!/'�,% '/;+Il/�f/%✓�l�i' �1'�/� r���/�!„-,; � r ,„ / ,,,�, ,,,,d ri, n„i ,,,rc,u, r���✓//���f/i//����/�/!����ij���r��ll/ u r 1 �� I ip fflr/ ✓ f r-� awn ANI) lll 100%Envis'o omental I E,rnptoyoIe Ow ned I Offices Nratia�nuMdL I Beo vnar)dCa(dw etLrln) ra r�t // This Final Report for the Butte County Stable Isotope Recharge Study(Study) is submitted in accordance with Attachment IIB of the County of Butte Contract Number X21825, dated September 15, 2015 between Butte County and Brown and Caldwell (BC). Stable isotopes are naturally occurring components of water.The stable isotope abundance changes with elevation and evaporation processes and can be used to identify sources of groundwater recharge. The purpose of this Study is to use stable isotopes to gain an improved understanding of groundwater recharge in eastern/central Butte County(the Focus Area of this Study).This Study included', preparation of a Technical Memorandum that summarized existing isotope data in Butte County, preparation of a Field Sampling and Analysis flan to obtain stable isotope data from 30 groundwater wells at 10 individual locations and 10 separate surface-water locations along creeks and rivers. Samples were cohected in October 2015, June 2016, October 2016 and March 2017.Thus, samples were collected near the end of an historic drought period in 2015, at the end of seasonally wet and dry periods in 2016, and during one of the wettest winters on record in early 2017.The analysis of the data supports the following findings.. A. Isotopic Variation by Season - Surface Water Stable isotope abundance in surface water is seasonally variable in the creek samples that flow from the Upper Watershed to the Valley Floor(e.g. Butte Creek, Big Chico Creek, Little Chico Creek) as shown in Figure ES-1. In contrast,samples from the Sacramento, Feather Rivers (Upper Watershed) do not show much seasonality, due to mixing that occurs in reservoirs that supply water to these Rivers. � Opp % i F f 'r wxERsneci Y ti 0 l' FLOOR �' LOVV'E ?;1 d r!� Y Fxrxiiiu A ES-1.. Range of Precipitation Types in Butte County Brown Caldwett : Stable Isotope FinaP Report 1 1-1 Part I//Executive Surnmary Butte Creek headwaters are located near Cirby Meadows, which is 6,260 feet (ft) above mean sea level (amsl), within the Upper Watershed.The Butte Creek samples collected in late winter (March) indicate that most of the runoff is from lower-elevation part:of the Upper Watershed rainfall (-2,900 ft amsl), based on stable isotope results. In June,the stable isotope ratios indicate a mix of high elevation. snowmelt with lower-elevation rainfall from the Upper Watershed. In October, Butte Creek samples have isotope patterns consistent with snowmelt(-4,800 ft amsl).The seasonal pattern of isotope data in Little Chico Creek (with headwaters at about 2,415 ft amsf)was reversed compared to Butte Creek, suggesting watershed elevation may have an effect on the seasonal variation of isotopic composition. Figure ES-2 summarizes the isotopic abundance of stable isotopes deuterium (D) and 18-oxygen (180). Surface water data close to the global meteoric water line (GMWL)suggest no significant evaporation. Data points along the GMWL also indicate elevation differences. 1111 .50 63ao=-0.9 6D -23.3 10/16 16 A 3/17 17 South Butte Creek 31tl�(low elevation) /cu 3fII7 6/1fi 3/17' 0 P5£t 511 1a�1a �ex¢w•,:ro- ,rr��• "75 61x6 X 10:/p, r.rtxo,t�,r i1o1'v / 1.0 15 !V01,irWe Cr NVV Y k57 70 1& ri X111 10145 Seo ves 1b/tG 10/15 1015 0 R AfTUCI'wy 10/.1'5 rr,Ii�1C d'o,r;y �.. 0 1 a ntt';€s C:' .. Ctd o�.r North Butte Creek 0 (high elevation) G1l�rrtr;.rk::rwt;, Sbrwr.,tt;rYr Itlw,;,b F1s,:¢rt) -100 -Y.2.5 1.2 .-;.1.5. ..11 _10 5 .„.0 9'. 51&0 ES-2.8p, 8180 in Surface Water Samples Groundwater samples were much less seasonally variable than surface water in their isotopic values at all locations. To develop a better understanding of potential seasonal variability in groundwater, additional information about the subsurface flow paths from recharge locations to individual wells would need to be developed', including the timing and rate of groundwater movement. Stable Isotope Final Report 1 1-2 Br WVt� a ldwell Park 1/✓Executive Summary Implications. Future recharge studies should take into consideration seasonality of water sources since this may affect the interpretation of stable isotope results from groundwater samples. B. Variation by area - Groundwater Three distinct areas have been identified based on isotopic signatures in the groundwater samples (see Figure ES-3). North Area.Shallow groundwater zones (<400 ft deep)are recharged by the Upper Watershed. intermediate and deep portions of the basin are recharged from the upper elevations of the Lower Foothills (<1,800 ft). East Area. Shallow portions of the basin (<200 ft deep)are recharged by local rainfall on the valley floor. Intermediate and deep portions of the basin are recharged from the Lower Foothills (<1,800 ft). South Area. Rainfall to the Valley Floor Is the dr�,( l ✓/i( ydr primary recharge Source' 4 �' rJl «/r there is some evidence that Imported irrigation water may be a source of recharge In some areas /i ( /4✓fr � I'4 r l I/ �" /;q // I ��r //if p/(,� U r%ry I `In Implications:W h i I e the '.e 4 ?,✓ V jY , j rri // f/I iJ l%.f f✓ r r ^, I/r�� ?d" r � '' ? ii r.a+. rivers and major creeks are contributors to / d ✓�//l !� /7p?f / / � 'P" N ? /✓ lMlrY�" /,%�� 'f6�6i%; Ilr ��y+k(/Ylrlf%/ �Plf Ydy ifr tN t, .;. it L /i///'rl / f Y r„2 a i eJr ? � ?' ,? I ✓��l�y ���ld��Jj�� ��W7" /F`��. �/," recharge In the North ir!?/i /i r /�i yt r sfJ/l ✓l r v.J ✓ ✓4,,r11dr fl/f// rl/�irir� �?!? �G///r Area,the Lower Foothills ;�,/ ' i�/ a.j ,✓ ��� . /,,/«�;��� �� p, , „ / a ,,1;,�//,r� ,;/� r� J, 4'l.,/� //�/I/ l °w'� ✓�����,JPpN '.n��l/// r% /d%r,N?err ? r1%//� dr>l r ��! hi l�///Jell t�J�/ and Valley Floor �i'; y % e,✓ � r rl��/ �J;Ir/ °//��/ �1, �` r� `i���/ I� rl>��' /1/�r��? precipitation are primary r oa / Jj sources of recharge -- ��li) ucgenr7 water throughout the IIle ITa "c,07 ✓/7 North, East and South d ° ✓ Nfi r?i u�d� ✓J ✓n / rY1, �/�7'H�//i//f//� J 1 /(4r GmW.Mo �n,w f� Su riac+..V'Mo;5:rrviaarr Cerc=r n�'�F Areas.Some evidence for /� 11 � ✓r l� ���/ ! f Jl/(i d �i/' i i�� � o irrigation water recharge , �� 4 d, r'r li ✓ua � � ,,/ ; Jo x'l�r/ ' (associated with rice farming) is indicated, but Figure ES-3.Groundwater Recharge in the Focus Area these data are limited to one shallow well in this Study. C. Limitations of Isotopic Studies The hydrogeologic (physical)framework of the aquifer dictates groundwater flow, including where rock craps out at the surface and allows rainwater to recharge the subsurface. In Butte County,the major geological formations (Lower Tuscan, lone and Mehrten) often overlap and constrain groundwater movement. Isotopic Studies are most effective when the local environment presents large variability in isotope signatures and can be correlated geologic formations and hydrostratigraphic layers. Brown—Caldwell I Stable Isotope Final Report 1 1-3 Part 1//FxecubveSummary D. Conceptual Site Model, Groundwater Recharge The Lower Tuscan Aquifer Study(LTA Study; BC, 2013) presented the hydrogeological framework for the Sacramento Malley groundwater basin in Butte County by describing many aspects of the Lower Tuscan Aquifer groundwater recharge. This stable isotope 'Study focuses on recharge sources and mechanisms in central Butte County by sampling surface water,groundwater, and stormwater samples for stable isotope analysis. Key findings related to the Conceptual Site Model are summarized below. Source Water Regions There are three primary source water regions for groundwater recharge in the Focus Area: • Upper Watershed.The Upper Watershed area is located topographically above the other source water regions. Geologically, it consists primarily of volcanic, granitic, and metamorphic rocks that o not have any appreciable primary porosity. Fracturing within these rock units may occur locally but the fractures are not pervasive on a regional scale, which limits the amount of water that can percolate into the bedrock geologic units and the volume of groundwater available to migrate to other regions.The Upper Watershed receives rainfall and snow, primarily during the winter and spring months. Rainfall runoff and snowmelt enters the Focus Area from major streams and rivers, including Butte Creek, the Sacramento River, and the Feather River; imported irrigation water also enters the Focus Area from Lake 0roville. • Louver Foothills.The Lower Foothills region occurs within a relatively narrow topographic band along the east edge of the Sacramento Valley.The Lower Foothills region contains the outcrop of the Lower Tuscan Formation in addition to small alluvial fans and other Recent sedimentary deposits that directly overly the Lower Tuscan Formation. Rainfall that occurs in the Lower Foothills may percolate Into the Lower Tuscan Formation and the Recent alluvial sediments or it may runoff through local, ephemeral streams to the Valley Floor. • 'Walley Floor.The Valley Floor defines the lowest elevation source water region in the Focus Area. It is underlain by Recent alluvial material in most areas, although the presence of hardpan layers may affect shallow percolation in some locations. There are no significant creeks or streams that originate on the Valley Floor. Rainfall that occurs on the Valley Floor may percolate locally or it may runoff into other creeks and streams that originate at higher elevations. Recharge Mechanisms The recharge mechanisms may vary by both depth and area across the groundwater basin within the Focus Area. North area.Within the shallower aquifer interval (above -400 ft bgs), the primary source of groundwater is from the Upper Watershed region, based on the isotope data. Wells to the east may be recharged from Butte Creek, whereas well's to the west may be recharged by flow from the Sacramento River. The data indicate that the intermediate and deeper depth intervals are recharged from rainfall and percolation in the Lower Foothills region.There is also the potential for Upper Watershed recharge in the shallow aquifer interval to be pulled down to greater depths due to irrigation pumping, causing a mixing of recharge sources in the intermediate and possibly deep intervals in the North Area. This mixing, however, is an anthropogenic effect and not necessarily a component of natural recharge that would' occur in the absence of large-scale pumping from intermediate and deep aquifer intervals in the North Area. Stafne Isotope Final Report 1 1-4 l 'rotnrrl ��ald''Wvell Part I f/ Executive Summary The isotope data demonstrate that the intermediate and deep intervals of the Lower Tuscan aquifer do not receive any appreciable recharge as a result of fracture flow or other mechanisms from the Upper Watershed. • mast Area. Recharge in the Fast Area wells is affected by evaporation, indicating some delay before the precipitation that forms the rainfall percolates into the subsurface. The shallow zone intervals are likely to be recharged by direct percolation primarily from Vailey Floor precipitation, supplemented by some rainfall recharge at the base of the Lower Foothills.The intermediate and deep zones are recharged from the lowest elevation part of the Lower Foothills region, most likely from percolation directly into the Lower Tuscan Formation at the outcrop or through recharge into the local alluvial fans and sedimentary deposits and subsequent downward vertical migration into the underlying Tuscan aquifer units.. The isotope data do not provide any indication that small creeks or streams originating in the Lower Foothills, or lateral movement of groundwater within the small alluvial fans and sedimentary deposits, provides any significant recharge to the shallow aquifer Interval at the edge of the Valley Floor in the Fast Area. Because there is no data to support any water from the Upper Watershed,the stable isotope data in groundwater indicates that virtually all recharge in the Fast Area is from local precipitation. • South Area. Wells completed within the Tuscan Aquifer units in the South Area all have a similar isotope signature, indicative of recharge from the lowest elevations of the Lower Foothills.This relationship infers that all recharge to these aquifer intervals occurs at the outcrop of the Tuscan Formation or through local alluvial fans and other sedimentary material directly overlying the Lower Tuscan Formation. The uniform isotope results with depth may also suggest the potential for mixing between different aquifer intervals.. Well 35C in the South Area is screened very shallow (<100 ft bgs)and is likely within the alluvium overlying the Tuscan Aquifers units. The isotope data indicates that the recharge for this well comes, in part, frorn imported irrigation water from the Feather River used for rice farming. Given the shallow nature of this well, it is also likely that some recharge of local rainfall occurs in the shallow alluvium. The isotope data are also consistent with aquifer pumping test resuVts from the LTA Study that demonstrate that the shallow alluvium is not in hydraulic communication with the underlying Tuscan Aquifers. Recommendations for Further Study Methodolo& Seasonal sampling should be performed as part of future surface water and groundwater isotope studies for purposes of assessing groundwater recharge. Monitoring,wells with multiple screened intervals (multi-completion monitoring wells) are recommended to assess stable isotope data at different depths. Sampling locations in this study with a single well-screen interval do not provide nearly as much insight as sampling locations with wells screened at multiple depths. Monitoring wells with relatively short screened zones(20 ft or less) are preferred to minimize mixing between aquifer zones or between aquifer zones and residual water retained within the aquitard zones between aquifers. The LTA Study determined that the aquitards can release large volumes of water to the aquifer in areas where large volumes of groundwater are extracted. =rOwn--.Ca1dwet1 scauie Isotope Final Report V , Part I//Executive Summary General • South Area wells. Conduct general mineral analysis on groundwater samples to evaluate whether elevated electrical conductivity(EC) values observed during sampling for this study are due to irrigation influences (e.g. elevated nitrate, calcium, sulfate) or due to proximity to the lone Formation (e.g. elevated sodium, chloride, and boron).This will help further characterize the recharge source. • Contribution of recharge from rainfall directly on the Lower Tuscan outcrop.Stable isotope abundances indicate that a substantial proportion of local recharge is derived from elevations consistent with the outcrop of the Lower Tuscan Formation (i.e. within the Lower Foothills). Thus, it is recommended that local precipitation be collected during an entire precipitation season at varying elevations across the outcrop and analyzed for stable isotopes to better correlate or calibrate the groundwater isotope values with local precipitation sources. • Recharge rate. Most well locations and depths should be sampled and analyzed for presence of tritium to help distinguish whether recharge to individual aquifer zones is occurring over periods shorter than about 60 years, or whether recharge is occurring over longer timeframes. arWatd Stable Isotope Final Report 1 1-Fa � wilt ro it TAC Itern 4-d Attachment 3TeChDiCai Need: East Butte Groundwater Basin (Project 3\ The East Butte Suhbanm(5-21,59)covers about 26750Vacres inthe Sacramento VaQeyGroundwater Basin andis aMedium Priority Subbasin(Document 2)1. |tis bordered byButte Creek tothe north and west,the Sutter Buttes in the south,foothills in the northeast,and the Feather River in the southeast.Agricultural land use consists primarily of rice production supported by both groundwater and surface water.To a lesser extent,orchard crops are grown iuareas having more permeable soils inthe northern portion ofthe xubbasloand these areas are predominately dependent ongroundwater. in addition,the communities of Gridley and Biggs are reliant on groundwater for municipal supplies. The East Butte aquifer system includes stream channel deposits, basin deposits,Sutter Buttes alluvium,and deposits ofthe Modesto, Riverbank,Tuscan and Laguna formations. Most ofthe higher producing agricultural wells draw good quality water from the Tuscan formation. The surface water irrigated areas primarily receive water from the Feather River and Butte Creek. This subbasin,although not designated a critically overdrafted basin, has areas with clechning groundwater levels, reduced groundwater storage,and has a connected groundwater-surface water system whereby pumping can induce stream depletion. in the groundwater dependent areas of the East Butte subbasin(Document 2), groundwater levels have declined on the order of 1-2 feet per year for the past 10 years,with the exception of a couple ofwet years(namely 20]6'ZO11and 2U17). This has resulted indeclines imgroundwater levels inthe primary pumping zone(100-450 feet below ground surface)of up to 17 feet and up to 15-20 feet in the adjacent West Butte subbasinsince 20O4(Document 14). Monitoring from adedicated monitoring well (Z0�NO2E24CVg1Nl) [mthe Cherokee Strip area ofthe East Butte subbasinisshown ioDocument 1J. This area|sgroundwater dependent and primarily produces orchard crops. The hydrographshows trends ingroundwater levels since ZOQO with declining spring levels onthe order of19feet from 2OD4mzZ81S. {msurface water irrigated lands, groundwater serves as an important water supply buffer in times of drought as experienced in 2015 when Feather River Settlement Contractors received water supply cutbacks under their contracts for the first time in23years. AddffiOn8iD�8t8Ni(--�2dS Over 79 wells in!the subbasin are monitored four times each year for groundwater levels. This monitoring network,existing geology cross sections and reports,and special studies on recharge in the area provide the basis for understanding basin conditions. However,additional data and analysis ioneeded. The basin,structure needs to be better defined to inform the hyclrogeoyogic conceptual model and further develop technical tools such as an integrated groundwater-surface water model that can adequately support sustainable management of the subbasin,including characterization ufstream-aquifer interactions. Geophysical data strategic placement of additional monitoring wells,and additional analysis and integration of existing data from well logs,water quality data, recharge reports,and geology studies is needed to support development of the Groundwater Sustainability Plan(GSP). This additional data will be critical for evaluating potential management actions to achieve sustaimabi1ty. Additional analysis of stream flow in relation to groundwater conditions is needed to better define stream-aquifer interactions and address clep|etions of interconnected surface waters in the GSP. Additional stream gaging stations may be necessary to adequately calibrate numerical models that will be needed to quantify water budget components such as change in storage,stream-aquifer interactions,and interbasin flows. Attachment 3 Techrka| Need: Wyandotte Creek Groundwater Ba3�n (Project 4) The Wyandotte Creek Subbaun(5-21.69)covers about 4B4OOQacres inthe Sacramento,Valley Groundwater Qasn (Document 2). It is bordered by the Feather River to the north and west, Honcut Creek to the south,and foothills to the east. In the northern portion near and around Oroville,the land use is primarily urban. In the centraU and southern portions,the land uses are a mix of rural residential and agriculturaL Agricultural land use is fairly diverse and consists ofacombination ofrice,orchards,grain,pasture,and field crops primarily supported bygroundwater. Groundwater is also used as a municipal water source for portions of Oroville and as an emergency source of municipal supply. The aquifer system includes recent valley sedimentary deposits,floodplain and alluvium deposits,and deposits ofthe Victor, Laguna, and yNehrtenformations. This subbamim,although not designated acritically mverdratedbasin, has areas with declining groundwater levels, reduced groundwater storage,and has a connected groundwater-surface water system whereby pumping can induce surface water depletion. Along the Feather River,surface water generally provides water for irrigation, Further east,groundwater serves as the sole source of agricultural irrigation water for a large area of the subbasin (Document 28). The Hmited network of monitoring wells show that water levels are relatively stable in some places,are affected by Feather River flows near the river,and have experienced declines during dry and critical years inother places, Groundwater levels in the main pumping zone(100-450 feet below ground surface)in this subbasin fell up to 13 feet from 2004 to 2017(Document 14). Monitoring from an irrigation well of intermediate depth (200-600 feet) near the county border on the east side of the subbasin showing declines ofspring groundwater levels onthe order af1Qfeet from 2O04tmZO15(Document 1S). /\MTiODg| DataNeedS Only about eight wells in the subbasin are monitored four times each year for groundwater levels. Although groundwater conditions are more variable and are not as well defined in this subbasin, managing water to facilitate additional recharge when water is available during wet or normal years will help reduce the wider variation mfwater levels experienced during drought years ingroundwater dependent areas lnthis sobbasin. Specific problem areas,potential water sources,and suitable recharge areas in this subbasin need to be identified and better characterized. The existing monitoring network,existing geology cross sections and reports,and special studies onrecharge in the area provide the basis for understanding bas[mconditiono. However,additional data and analysis isneeded. The basin structure needs to be better defined to inform the hydrogeologic conceptual model and further develop technical tools such as an integrated groundwater-surface water model that can adequately support management ofthe su66ouin,including characterization ofstream-aquifer interactions. Geophysical data, strategic placement of additional monitoring wells,and additional analysis and integration ofexisting data from well logs,water quality data,recharge reports,and geology studies lsneeded tosupport development ofthe Groundwater Sustainability P|an (GSP). This additional data will becritical for evaluating potential management actions toachieve sustainability. Additional analysis of stream flow in reIation to groundwater conditions is needed to better define stream-aquifer interactions and address depletions of interconnected surface waters,in the GSP. Additional stream gaging stations may be necessary to adequately calibrate numerical models that will be needed to quantify water budget components such as change in storage,streaim-aquifer interactions and interbasin flows. Attachment 3Tech0'ca| KUeed: ViDa Groundwater Basin (Project 1\ ` ~ ' The Wna5obb�asin(5-21.57)covers about 1Z6,V0Qacres inthe Sacramento Valley Groundwater Basin(Document 2), Itixbordered byneer[neekinthanmrth,Big Chico Creek tothe south,the Sacramento River tothe west,and the foothills to the east. In a normal water year,about half of the Vina subbasin is in summer agricultural production supported predominantly bygroundwater(Document 2O). Agricultural land use consists primarily of orchard crops,lairgely almonds and walnuts. In addition,Vina includes a portion of Cal Water Service-Chico(CWS- Chico)s*m[ceareo,wh|:husesgroundwaterasthesm|emunidpa|mmtersouvce[ormuchufthe[hlcourbananea. The Vina aquifer system includes stream channel and alluvial fan deposits,and deposits of the Modesto and Tuscan formations. This smbbasin,although not designated a critically overdrafted basin,has areas with declining groundwater levels, reduced groundwater storage,degraded water quality,and has a connected groundwater-surface water system whereby pumping can induce surface water dep�|etimn. The Department nfToxic Substances Control iscontinuing its efforts to protect public health and oversee characterization and remediation of chlorinated solvents contamination|nChico groundwater. Chico area septic systems have elevated the levels of nitrates in the shallow aquifer contaminating drinking water pumped from shallow wells. However,septic systems have been phased out ofthis area imresponse to,potential pollution concerns. Groundwater levels have been declining oothe order of1-2feet per year for the past 10years,with the exception ofacouple ofwet years(20O6,ZQ11and 2O17). This has resulted lndeclines ingroundwater levels inthe primary pumping zone(lO0-450feet below ground surface)nfupuo13feet(Document 14). Anumber cdmonitoring wells with long periods ofrecord are reaching new historical lows. These wells tend tobeshallow(<2UOfeet)domestic wells,however irrigation wells have reportedly experienced water supply reliability issues(reduced production, reduced pressure oradditional sand) iorecent years eswell. Monitoring from ashallow domestic well near the center of the subbasin,23NOIW36PO01M,shows groundwater levels with recently declining spring levels on the order of16feet from 3O041o2O15(Document 8). Additional Data Needs About 96 wells in the subbasin are monitored four times each year for groundwater levels. This monitoring network,existing geology cross sections and reports,and special studies onrecharge inthe area provide the basis for understanding basin conditions. However,additional data and analysis ioneeded. The basin structure needs to be better defined to inform the hydrogeologic conceptual model and further develop technical tools such as an integrated groundwater-surface water model that can adequately support management of the subbasin,including characterization ofstream-aquifer interactions. Geophysical data strategic placement mfadditional monitoring wells,�nd additional analysis and integration of existing data from well logs,water quality data,recharge reports, and geology studies is needed to support development of the Groundwater Sustainability Plan(GSP). This additional data will becritical for evaluating potential management actions toachieve sustainability. Potential water sources and suitable recharge areas inthe Vimasubbayimneed tmbeidentified. Additional analysis ofstream flow in relation to groundwater conditions is needed to better define stream-aquifer interactions and address dep|edmnsofinterconnected surface waters|nthe E5P. Additional stream gaging stations may benecessary to adequately calibrate numerical models that will beneeded tuquantify water budget components such aschange instorage,stream-aquifer interactions and intorbmalnf|uwm. AttaChU7ert 3Tp[hni[a| Need: West Butte GrOUndVVater Basin (Project 7) The West Butte Subbasin(5-Z1.5Q)covers about 18D,4Q0acres inthe Sacramento Valley Groundwater Basin (Document 2). kisbordered byBig Chico Creek tothe north, Butte Creek nothe south,the Sacramento River to the west and the foothills tothe east. Groundwater serves as the sole source of agricultural irrigation water for a large area ofthe West Butte yubbesin(Document 20)supporting primarily orchard crops,largely almonds and walnuts. Another significant portion of the subbasin produces rice irrigated by surface water primarily from the Feather River. Asmaller portion 7swithin the Cal Water Service-Chico service area using groundwater asthe sole municipal water source for the Chico urban area. The West Butte aquifer system includes stream channel deposits, basin deposits,Sutter Buttes alluvium,and deposits ofthe,Modesto, Riverbank,Tuscan and Tehama formations. This subbasin,although not designated a critically overdrafted basin, has areas with decilning,groundwater levels, reduced groundwater storage,degraded water quality,and has a connected groundwater-surface water system whereby pumping can induce surface water depletion. The Department ofToxic Substances Control iscontinuing its efforts toprotect public health and oversee remediation ofchlorinated solvents contamination in Chico groundwater. Chico area septic systems have elevated the levels of nitrates in the shallow aquifer contaminating drinking water pumped from shallow wells. The greatest groundwater level declines have occurred inthe Durham area south ofChico. Declining groundwater levels have occurred inthe primary pumping zone(1D0'4S8feet below ground surface)ofupto2lfeet from 20O4to2817(Document I4). Anumber ofmonhoringwells with long periods ofrecord are reaching new historical lows. These wells tend tobeshallow(<2O0feet)domestic or irrigationwei|s. Wells in this subbasin have reportedly expedenced water supply reliability problems in recent years. This results inconstruction ofnew wells ordeepening existing wells. Monitoring from ashallow domestic well (21NO1E27DO01M)in the groundwater dependent area shows groundwater levels,with declining spring levels mnthe order ofZ4feet from ZUU4mo2QlS(Document 1&). Shallow domestic wells surrounded bygroundwater dependent irrigated agriculture are especially vulnerable to going dry as water levels drop during the irrigation season. Ad6tiDi4 �Da,ta Ne�eds About 67 wells in the subbasin are monitored four times each year for groundwater levels,. This monitoring network,existing geology cross sections and reports,and special studies on recharge in the area provide the basis for understanding basin conditions. However,additional data and analysis iyneeded. The basin structure,needs to be better defined to inform the hydrogeologic conceptual model and further develop technical tools such as an integrated groundwater-surface water model that can adequately support management of the subbasin, including characterization ofstream-aquifer interactions. Geophysical data,strategic placement ofadditional monitoring wells,and additional analysis and integration of existing data from well logs,water quality data,recharge reports, and geology studies is needed to support development of the Groundwater Sustainability Plan(GS,P). This additional data will be critical for evaluating potential management actions to achieve sustainability. Potential water sources and suitable recharge areas in the West Butte subbasin need to be identified.Additional analysis of stream flow in relation to groundwater conditions is needed to better define stream-aquifer interactions and address depletions ofinterconnected surface waters[mthe GSP. Additional stream gaging stations may be necessary to adequately calibrate numerical models that will be needed to quantify water budget components such as change in storage,stream-aquifer interactions and interbasin flows,