Repairing a Damaged Ecosystem
(Used with permission from Mono Lake Committee, please see website for more articles and information)
The long legal struggle that saved Mono Lake also set the stage for restoring many of the Mono Basin’s damaged resources. Today, Mono Lake is rising and its streams are in the early stages of re-establishing the natural processes that once supported lush cottonwood-willow forests and thriving fish populations. As this recovery proceeds over the next 20 years, there will be much to observe, document, and learn. Restoration is an emerging field of knowledge—half science, half art. Mono Lake’s recovery over the next 20 years offers a dynamic lesson in restoration that we are all privileged to witness.
PREDIVERSION MONO BASIN: A RICH AND DIVERSE ECOSYSTEM
Before the turn of the century, all water in the Mono Basin watershed flowed into Mono Lake. Millions of migratory waterbirds depended on the lake’s unique ecosystem, teeming with brine shrimp and alkali flies, and on its associated mix of habitat types, including islands, protected lagoons and lake-fringing springs and wetlands. The mouths of streams, where the fresh water mixed with the lake’s briny water, provided particularly productive environments where waterbirds could rest, bathe and feed. Up from the lake, Mono Lake’s tributary streams meandered through the arid Great Basin landscape, supporting lush bottomlands in the stream floodplain. These “wooded wetlands” featured multistoried cottonwood forests, deep meandering multiple stream channels, backwater ponds, and wet meadows.
WATER DIVERSIONS AND DAMAGED ECOSYSTEMS
Between 1852 and 1941, the Mono Basin was just beginning to be impacted on mostly a small scale by Euro-American settlers. Streams were partially diverted to irrigate ranches, but this water remained in the watershed, flowing eventually to Mono Lake. Sheep and cattle grazing on various ranches damaged streambanks and vegetation. But it wasn’t until 1941, with the extension of the Los Angeles Aqueduct to the Mono Basin, that large-scale damage began to take place. Four creeks were diverted into the aqueduct, drying up the streams below the diversion dams. Riparian vegetation died, fisheries were destroyed, and occasional floods tore through the desiccated floodplains plugging up side channels and turning the main channels into wide, straight washes. Deprived of most of its inflow, Mono Lake dropped 45 vertical feet, lost half its volume, and doubled in salinity by 1982. The result was a fragmented and poorly functioning ecosystem. Islands where California Gulls nested became peninsulas accessible to predators. Toxic alkali dust storms arose on windy days from exposed salt flats. The numbers of ducks and geese plummeted by 99%.
RESTORING THE MONO BASIN: HEALING MUCH—BUT NOT ALL—OF THE DAMAGE
As a result of litigation pursued by the Mono Lake Committee, National Audubon Society, California Trout and others, first the courts and subsequently the State Water Resources Control Board ordered restoration of the area’s damaged resources. The L.A. Department of Water and Power is responsible for implementing the Water Board-approved restoration plan.
Today, Mono Basin restoration is aimed at restoring natural processes and ecological function. Raising the level of the lake will lower its salinity, reduce dust storms and reconnect the lake to springs and deltas. Reinstating stream flows that mimic natural flows, particularly the annual spring flood, will provide the dynamic energy needed to rebuild deep stream channels and pools, re-grow riparian forests and reestablish healthy floodplains.
Because water will continue to be diverted to L.A., the Mono Basin resources will not be completely restored. The lake will still be 25 feet lower than its prediversion level, the streams will carry less annual flow than they once did, and the former cottonwood-willow riparian forests will take 50 years to mature. Certain features, most notably the delta of Rush Creek, have been so downcut by incision that they cannot be brought back in anything less than geologic time.
Perhaps the greatest lesson of Mono Lake is that it is always better to prevent damage than to rely on restoration. Nonetheless, restoration holds promise that many of the Mono Basin’s damaged resources may recover.
THE MONO LAKE COMMITTEE AND RESTORATION
Part of the mission of the Mono Lake Committee is to restore the important habitats of the Mono Basin. The Committee believes that the best and most cost-effective method of restoration is re-establishing natural processes. This means establishing peak flows on the creeks that give the creeks enough energy to recreate their former habitats without significant intervention or continued maintenance. When past degradation is such that it is difficult to reinstate natural processes, the Committee supports a limited “helping hand,” such as reopening side channels on the streams to raise water tables and provide complex habitat, or planting native vegetation to jump-start streambank recovery.
Today, the Mono Lake Committee serves as “watchdog” for the restoration process, reviewing annual monitoring reports produced by consultants hired by the LADWP, commenting on any changes to the program proposed by LADWP or others, and generally participating actively as an “interested party” in all aspects of the restoration. In addition, the Committee organizes volunteer restoration events that support the Water Board-approved restoration program and offers restoration interpretive activities.