The Los Angeles Aqueduct is a fixture in the Mono Basin, and few here can remember a time before it existed. Today it remains at the center of issues with the Los Angeles Department of Water & Power (DWP), especially as the three-year anniversary approaches of the effort to implement restoration streamflows that will heal the damage done by decades of excessive water diversions enabled by the aqueduct.
For the Mono Lake Committee, the aqueduct and the water it diverts from Mono Lake’s tributary streams have always been an important focus, but in years past the issue was how much water was inside that buried concrete pipeline to Los Angeles—and how much remained in the Mono Basin for the lake and streams. That was settled with the landmark 1994 State Water Resources Control Board decision, which established a long-term, ecologically-sound management level for the lake, created a restoration program for the desiccated streams, and allocated continued water for export.
Now, after a decade of study and with the summary report from the State Water Board’s expert stream scientists in hand, the physical aqueduct infrastructure has become the focal issue of the day. How can the limitations of the pipes, dams, ditches, structures, and valves be overcome in order to release the ecologically beneficial amount of water the streams need at the times of year they need it most?
The good news is that solutions are available that provide both healing for the streams and benefits to DWP. Principled win-win solutions are the hallmark of water issue history at Mono Lake, and the Committee expects nothing less for the critical issue of stream restoration.
Will DWP sign on to win-win solutions?
As a result of a lengthy, productive, often technical, and occasionally frustrating, collaborative discussion and negotiation process with DWP and other key parties, we have arrived at feasible solutions to implement the stream scientists’ prescriptions developed over the past decade. Here at the Committee, we hope that DWP has signed on to these solutions by the time our latest Newsletter reaches you.
The collaborative process has resolved substantial issues of disagreement, in large part through joint hydrologic analysis of streamflow and aqueduct operation using a sophisticated, collaboratively developed, Mono Basin water balance model. The process has also identified win-win solutions that will achieve the restoration the streams deserve without altering a single gallon of the City‘s existing water supply from the Mono Basin.
The Committee sees the following as the key elements to a successful agreement that all parties can support:
• Fulfillment of existing legal commitments and the obligations of DWP’s Mono Basin water licenses by implementation of the mandated 2010 science-based stream restoration plan;
• Enhancement of the restoration of fisheries and riparian habitats of Rush, Lee Vining, Walker, and Parker creeks;
• Creation of modern infrastructure and reliable operational rules for DWP to continue authorized exports of Mono Basin water;
• Establishment of mechanisms for efficient, long-term Mono Basin monitoring, adaptive management, and restoration programs that minimize controversy while achieving the mandates set by the State Water Board;
• Containment of the cost of infrastructure upgrades.
The aqueduct’s limitation
The main challenge is DWP’s World War II-era Los Angeles Aqueduct infrastructure in the Mono Basin. The aqueduct was not designed or built to routinely allow water to pass down Mono’s tributaries in an ecologically sound manner. It was designed to capture the full flow of the tributaries, which it did for decades. Since then, stream restoration and the flow of water to the lake have depended on the use of spillways, bypass valves, and return ditches. No one would construct the system that way today—it’s simply what has been inherited from a bygone era. The facilities don’t have the physical capacity to release the right amount of water into the streams at the right times of year.
Here’s one example of that problem: One way of releasing water to Rush Creek requires draining the aqueduct pipe, then having DWP employees climb into the aqueduct conduit and barricade the inside of the pipe, then refilling the pipe so it overflows out a nearby bypass gate, then draining it again, then having employees return to remove the barricade materials. Obviously, a modern structure would have a release valve built in—probably one that could be operated and monitored remotely from DWP offices in Bishop.
Aging infrastructure needs upgrading
The aqueduct is well maintained, but it is getting old. Even if you forget restoration for a moment, major facilities questions still loom for DWP. There are questions about facility reliability, structural integrity, the amount of time invested in operations and maintenance, and operational protocols. DWP can keep maintaining the system it has piece by piece, or it can invest in facilities that meet their modern day mandates—that now include the needs of the lake and streams—for the decades ahead.
We’re confident that solutions for stream restoration, such as modern water release facilities, are also solutions that meet challenges already facing Los Angeles, such as assuring compliance with State Water Board requirements and reliably exporting the millions of dollars’ worth of Mono Basin water allocated to the city.
There’s already an example of how this type of solution can achieve benefits on all of these levels—you only have to look as far as the Lee Vining Creek diversion facility. A few years back DWP removed an entire section of the dam and installed a modern, real-time adjustable gate. This gate assures that state-mandated streamflow requirements are delivered and that restoration requirements such as passing sediment and peak flows are accomplished. And the benefits for DWP? It gained certainty that streamflow requirements would be met, allowing greater certainty to continue the export of water, as allowed, from the creek.
Seeking a centennial year solution
DWP has launched celebrations for the centennial anniversary of the Los Angeles Aqueduct. It is the perfect opportunity for DWP to put forth a modern, balanced, environmentally responsible vision for the next century of aqueduct operations.
An agreement to implement state-mandated stream restoration flows and to heal Mono Lake’s four tributaries—if adopted by DWP—will go a long way in establishing such a proactive and positive vision.
Indeed, a solution for Mono Basin stream restoration will be worthy of celebration, just as the 1994 Mono Lake decision was. And it will provide a statewide showcase for how the use of the best available science can achieve the dual goals of a restored environment and improved water supply reliability.