Near-stream Recharge to Protect Baseflows in the Upper San Pedro River, Arizona, USA Laurel J. Lacher, PhD, RG October 17, 2013 ISMAR8 Conference Beijing, China Lacher Hydrological Consulting photo credit: The Nature Conservancy

Acknowledgements The Nature Conservancy: Holly Richter Brooke Bushman David Gann Dale Turner

San Pedro River

Why is this little river so important? BIODIVERSITY 84 species of mammals > 41 species of reptiles and amphibians > 100 species of breeding birds > 250 species of migratory birds 6 native fish species San Pedro River Downstream of the Riverstone Tract (photo by D. Haddad, Arizona State University) San Pedro River (Photo by Jeff Smith)

San Pedro River Arizona, United States Sonora, Mexico N Babocomari River Rio de Fresnos N 10 miles

cu-ft/s (cu-m/s) (-0.06 to -0.03) (-0.03 to -0.003) (-0.003 to 0.003) km 8.3 16.6 25 miles

PURPOSE OF STUDY: To evaluate the potential for near-stream recharge to sustain or improve existing baseflows in the San Pedro and Babocomari rivers over the next century.

RECHARGE RATE OPTIMIZATION

baseflows at or above 2003 levels for 100 years? QUESTION: How much recharge would it take at each site to maintain baseflows at or above 2003 levels for 100 years? 3.7 3.1 2.5 1.9 1.2 0.6 AF/yr MCM/yr

QUESTION: Can simultaneous recharge increase efficiency? Water Savings 3,800 AF/yr (4.7 MCM/yr) Average water savings: 364 AF/yr (0.45 MCM/yr)

Optimized Simultaneous Recharge at Three Sites Simulated Difference in Baseflow from 2003 Conditions Optimized Simultaneous Recharge at Three Sites cu-m/s -0.04 to -0.03 -0.03 to -0.01 -0.01 to -0.003 -0.003 to 0.003 0.003 to 0.01 0.01 to 0.03 0.03 to 0.04 0.04 to 0.06 0.06 to 0.07

Take-Home Points Targeted near-stream recharge can protect baseflows. Simultaneous operation of sites improves efficiency. Thank you! Laurel Lacher LLacher1@msn.com

Cubic-meters (cu-m) 1.7E06 1.5E06 1.2E06 0.99E06 0.74E06 0.49E06

PREDICTIVE Pumping Recharge ET Baseflow Recharge (cu-m/yr) 7.4E07 PREDICTIVE Pumping Recharge (cu-m/yr) Recharge ET Baseflow

Streamflow Gaging Station Simulated Drawdown – Primary Regional Aquifer Contour interval = 5 m 20 15 10 5 Drawdown (m) San Pedro River Babocomari River San Pedro River Babocomari River San Pedro River Babocomari River 3511500 3501500 3491500 3481500 3471500 3461500 3451500 3441500 3431500 Palominas Hereford Sierra Vista Palominas Hereford Sierra Vista Palominas Hereford Sierra Vista Streamflow Gaging Station Mexico United States N UTM Latitude (m north) [a] 2000 [b] 2050 [c] 2100 555250 556250 557250 558250 559250 Cananea Cananea Cananea UTM Longitude (m east)