Colorado River Basin Overview of Yuma Area Water Operations and Salinity Management IBWC Colorado River Citizens Forum May 19, 2021 Interior Region 8: Lower Colorado Basin 2 Lower Colorado River Operational Objectives • Boulder Canyon Project Act of 1928 o Established the Secretary of the Interior as Water Master of the Lower Colorado River o Authorized the construction of Hoover Dam – Provide flood control and river regulation – Deliver water to meet irrigation and domestic uses – Generate hydropower • 1944 U.S.-Mexico Water Treaty o Meet water delivery and salinity requirements under the Treaty and Minutes 3 Overview of Yuma Area Operations and Salinity Management 4 Yuma Area Water Operations Overview • Delivery of Colorado River Water o Parker Dam → Imperial Dam → International Border o Parker Dam releases approximately 6.5 million acre-feet (maf) annually (~70 % of Lake Mead’s average annual release) o Customers in California, Arizona, and Mexico • Primary Goals o Satisfy water orders while meeting salinity requirements o Minimize excess flows to Mexico to conserve system water o Maximize groundwater production within salinity limits 5 Parker Dam Imperial Dam Senator Wash Brock Reservoir 6 Overview of IBWC Minute 242 • Background • Key Provisions • Of the approximately 1,360,000 acre-feet delivered to Mexico upstream of Morelos Dam, the average annual salinity will not be more than 115 ppm +/- 30 parts per million (ppm) over the annual average salinity (by the U.S. count) of Colorado River waters arriving at Imperial Dam • The U.S. may deliver up to 140,000 acre-feet to Mexico at the land boundary at San Luis, Mexico as part of the 1.5 maf Treaty delivery with a salinity essentially the same as that of the waters customarily delivered there (approximately 1200 to 1800 ppm) • Allows for up to a specified volume of groundwater pumping in both countries within 5 miles (8 kms) of the land boundary at San Luis 7 Senator Wash Deliveries to Mexico and Reservoir Coordination with IBWC Imperial Dam Laguna Dam Siphon Drop Power Plant Pilot Knob Power Plant NIB Morelos Dam 8 Senator Wash Deliveries to Mexico and Reservoir Coordination with IBWC Imperial Dam Example: 700 ppm salinity Laguna Dam Siphon Drop Power Plant Salt load influx from measured and unmeasured sources such as agricultural return flows, groundwater pumping, subsurface drainage, and other sources Pilot Knob Power Plant NIB Morelos Dam Example: Cannot exceed 845 ppm (annual average) 9 PPM Salinity Differential = 103 ppm * 10 *Example for demonstrative purposes only “DPOC” refers to the Drain Pump Outlet Channel (DPOC) drainage system and pumping wells Estimated Flows Arriving at the NIB Based on Calendar Year 2018 Volumes South Gila Valley DPOCs Yuma Mesa Conduit 2% 1% In 2018, pumped groundwater was (1705 ppm) (1740 ppm) approximately 3% of total volume Unmeasured Flows Below Imperial Dam 13% 19% delivered to Mexico at the NIB (1260 ppm) (695 ppm) • South Gila Valley DPOCs – 2% Other Measured Flow 6% • Yuma Mesa Conduit – 1% (1134 ppm) Yuma Main Canal Wasteway 7% (732 ppm) Pilot Knob Power Plant Wasteway 51% (678 ppm) 11 12 Colorado River Salinity from 1974 through 20191974 through from Salinity Colorado River Parts per million (ppm) 1000 700 800 900 400 500 600 1974 1975 1976 1977 Dam at Imperial Arriving Water Annual Salinity of 1978 1979 1980 1981 1982 1983 1984 1985 1986 Salinity at Imperial 1987 1988 1989 1990 1991 1992 1993 1994 1995 Linear (Salinity at Imperial) at (Salinity Linear 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Challenges • Decreasing salinity of water arriving at Imperial Dam and reduced river flows makes it challenging to meet the Questions?salinity differential • The likelihood of further reduced flows under shortage and low elevation reservoir conditions in the future will make it even more challenging • Managed groundwater is only a small percentage of the total volume of water delivered at NIB and operational options are limited • Continued coordination and better understanding of the salt load budget below Imperial Dam is crucial 13 242 Wellfield Expansion Project 14 242 Wellfield Expansion Project Overview • The project began in 2016 • Two components/pipelines: o 242 Wellfield Expansion o Yuma Mesa Conduit Extension 15 242 Wellfield Expansion Project Status • The 242 Wellfield Expansion component began operational testing in December 2020 o Create up to 32,000 AF of system water each year to help meet Federal DCP efforts • The Yuma Mesa Conduit (YMC) Extension component is under construction and anticipated to be completed in Fall 2021 16 17 For further information, please visit: https://www.usbr.gov/lc/riverops.html https://www.usbr.gov/lc/yuma/facilities/yao_wellfields_map.html.