ENGINEER'S REPORT ON WATER SUPPLY AND REPLENISHMENT ASSESSMENT Lower Whitewater River Subbasin Area of Benefit 2011-2012 Prepared for COACHELLA VALLEY WATER DISTRICT May 2011 5/24/2011 File: 0643.533 COACHELLA VALLEY WATER DISTRICT ENGINEER'S REPORT ON WATER SUPPLY AND REPLENISHMENT ASSESSMENT LOWER WHITEWATER RIVER SUBBASIN AREA OF BENEFIT 2011-2012 Prepared by Environmental Services Division Engineering Department May 2011 COACHELLA VALLEY WATER DISTRICT BOARD OF DIRECTORS Peter Nelson .....................................................................................................................President John Powell .............................................................................................................. Vice President Patricia A. "Corky" Larson ................................................................................................... Director Debi Livesay ....................................................................................................................... Director Franz De Klotz .................................................................................................................... Director OFFICERS & COUNSEL Steve Robbins............................................................................. General Manager-Chief Engineer Jim Barrett ............................................................................................ Assistant General Manager Gerry Shoaf .................................................................................................... Redwine and Sherrill Julia Fernandez ..................................................................................................... Board Secretary ENGINEERING Mark L. Johnson ......................................................................................... Director of Engineering Steve Bigley .................................................................................Environmental Services Manager i TABLE OF CONTENTS Page INTRODUCTION ............................................................................................................................1 GROUNDWATER BASIN DESCRIPTIONS ....................................................................................2 Geology ...............................................................................................................................2 Mission Creek Subbasin ......................................................................................................5 Desert Hot Springs Subbasin ..............................................................................................5 Garnet Hill Subbasin............................................................................................................5 Whitewater River (Indio) Subbasin ......................................................................................6 Palm Springs Subarea .............................................................................................7 Thermal Subarea .....................................................................................................7 Thousand Palms Subarea .......................................................................................9 Oasis Subarea .........................................................................................................9 Summary .................................................................................................................9 WATER SUPPLY ..........................................................................................................................10 Groundwater Storage ........................................................................................................10 Groundwater Levels ..........................................................................................................1 1 Lower Whitewater River Subbasin Area of Benefit Boundary................................. 15 Groundwater Production ........................................................................................ 18 Groundwater Inflows and Outflows ........................................................................18 Overdraft ................................................................................................................19 REPLENISHMENT PROGRAM ....................................................................................................20 Current Recharge Activities ...............................................................................................20 Monitoring Wells ....................................................................................................21 Recharge Facilities ................................................................................................21 Future Recharge Activities ................................................................................................26 Coachella Valley Water Management Plan ............................................................26 Recharge Model Projections..............................................................................................26 Other Replenishment Activities ..........................................................................................30 REPLENISHMENT ASSESSMENT ..............................................................................................30 State Water Code ..............................................................................................................30 Replenishment Water Costs ..............................................................................................31 Previous Replenishment Costs ..............................................................................31 Proposed Replenishment Costs .............................................................................31 Assessed Production .........................................................................................................34 Methods for Determining Production .................................................................................34 Replenishment Assessment Charge .................................................................................35 CONCLUSIONS AND RECOMMENDATION ...............................................................................38 BIBLIOGRAPHY ..........................................................................................................................39 Appendix 1: Historical Well Depth to Water Measurements .................................................... 41 ii FIGURES Figure 1 Coachella Valley Groundwater Subbasins ............................................................... 4 Figure 2 Historical Groundwater Levels in Indio Area (5.3 Miles from TEL) ......................... 12 Figure 3 Historical Groundwater Levels in La Quinta Area (2.4 Miles from TEL) .................. 12 Figure 4 Historical Groundwater Levels in Thermal Area (4.0 Miles from TEL) .................... 13 Figure 5 Historical Groundwater Levels in Valerie Jean Area (4.3 Miles from TEL) ............. 13 Figure 6 Historical Groundwater Levels in Mecca Area (9.6 Miles from TEL) ....................... 14 Figure 7 Historical Groundwater Levels in Oasis Area (12.4 Miles from TEL) ...................... 14 Figure 8 Historical Groundwater Levels at County Line (16.0 Miles from TEL) .................... 15 Figure 9 Lower Whitewater River Subbasin Area of Benefit ................................................. 16 Figure 10 Lower Whitewater River Subbasin Area of Benefit ................................................. 17 Figure 11 Groundwater Levels Downstream of TEL Recharge Facility .................................. 22 Figure 12 Historic Groundwater Levels at TEL Recharge Facility Monitoring ......................... 23 Figure 13 Historic Groundwater Levels North of TEL Recharge Facility ................................. 24 Figure 14 Historic Groundwater Levels Northeast of TEL Recharge Facility .......................... 24 Figure 15 Historic Groundwater Levels Southeast of TEL Recharge Facility ......................... 25 Figure 16 Whitewater River Subbasin - Change in Water Levels from 1999 to 2035 ............. 27 Figure 17 Increased Water Levels Due to Recharge, Year 2015 ........................................... 28 Figure 18 Increased Water Levels Due to Recharge, Year 2040 .......................................... 29 TABLES Table 1 Estimated Groundwater Storage Capacity ............................................................. 10 Table 2 Estimated Groundwater Production .......................................................................18 Table 3 Calculation of Overdraft in the Lower Whitewater River Subbasin ......................... 19 Table 4 Lower Whitewater River Subbasin Annual Recharge Deliveries ............................ 20 Table 5 Replenishment Assessment Charge (RAC) for Fiscal Year 2011-2012 ................. 32 Table 6 Estimated Producer Replenishment Costs for 2011 ............................................... 36 iii COACHELLA VALLEY WATER DISTRICT INTRODUCTION This is the eighth annual Engineer’s Report on Water Supply and Replenishment Assessment for the Lower Whitewater River Subbasin Area of Benefit managed by the Coachella Valley Water District (CVWD). This program began in the 2004-2005 fiscal year and has replenished the lower portion of the Whitewater River Subbasin with a cumulative total of approximately 97,222 acre-feet (AF) of supplemental water. CVWD serves an area of