A “pre-construction evaluation” report to replace Well 247 in the Laws area to the west of Highway 6 was on the agenda of the October 18th Technical Group meeting. LADWP plans to file a Notice of Exemption where the project would be exempt from an environmental review under CEQA. The Inyo County Water Department supported the proposal. The public attending, who spoke, did not. Why?
Well 247 is used to irrigate 100 acres of pasture. The duty for this pasture is 3 af/acre for a total of 300 af/yr; a relatively small amount. It is also a production well although it hasn't been used for export for the past 25 years due to the loss of water in getting it to the Owens River. Wells are expensive so why is LADWP replacing a well that works just fine and pumps 5.3 cfs of water? Well 247 is an old well (from 1928), old wells break down, and LADWP is obligated to irrigate the pasture as a mitigation project whether the well is broken or not.
Our main concern is the trend that LADWP is tapping a deeper aquifer when it replaces a well. The replacement for Well 247 will be 200 feet deeper and confined to a deeper aquifer where the existing well taps a shallow aquifer and possibly pulls from an aquifer below the shallow aquifer. Pumping deeper aquifers will create smaller cones of depression and will have less impact on the surface vegetation in the short-term. However, pumping deeper aquifers can cause subsidence and environmental damage in the long-term. The Inyo County Water Department (ICWD) has a good hydrology modeling tool that has been calibrated with past data and it has data on the many deep monitoring wells throughout the Owens Valley. They also monitor artesian wells and springs and would know if the flows are declining or the shallow water table is dropping. (The artesian wells along the Owens River/1872 Fault bring water up form the deeper aquifer.) They say they would be able to identify the well that is causing a problem.
Then the tricky part is the response. Would LADWP stop or reduce its pumping. If so, how quickly? Unfortunately, under the Long-Term Water Agreement, they have some leeway to over-pump a wellfield; in the deep or shallow aquifers.