Mono Lake is a stopover point for millions of birds between summer and fall. More than 100 species have been recorded in the area. Among the most common are Eared Grebes, Wilson’s Phalaropes, and Red-necked Phalaropes. Additionally, Mono Lake is one of the largest California Gull rookeries in the country. Major food sources for visiting birds are the lake’s brine shrimp and alkali flies. The migrating birds gorge themselves, significantly increasing their weight before moving on. As a result, Mono Lake has been designated as a part of the Western Hemisphere Shorebird Reserve Network, which means it is considered a critical migratory bird habitat.
Mono Lake is at least 760,000 years old and possibly as old as 3 million years. It’s among the oldest lakes in North America. At its deepest it is 159 feet, and it averages 57 feet, but this doesn’t adequately tell its story. In 1941, Los Angeles began diverting water from Mono Lake’s tributary streams to accommodate its growing water demand. This drastically reduced the water level at Mono Lake, harming the ecosystem. By 1995 the lake’s original shoreline location was more than a mile inland. Today Mono Lake is returning but water levels remain a problem. The water level goal identified at the time of the 1994 landmark decision will not be met and restoration work is ongoing. This is affecting the California Gulls nesting habits and the number of ducks visiting the lake.
First light shining on the Sierra Nevadas from Mono Lake.
Impact on California Gulls
Mono Lake’s Negit Island was an important nesting site for California Gulls. These gulls build nests on the ground where the eggs are exposed. An island provides protection from land predators like coyotes. By 1977, receding water levels connected Negit to the mainland. Coyotes began to access the site to feed upon the eggs and chicks (evidence supporting this claim includes the tracking of coyotes fitted with radio collars, the presence of eggshells in coyote scat and other studies such as those showing how the general presence of land predators may impact nesting habits even if predation does not actually occur). As a result, the Gulls nested elsewhere – both at alternative locations within Mono Lake and in other locales. By the 1990s, conservation efforts succeeded in raising the lake level enough to submerge the Negit “bridge” but the Gulls still haven’t made a meaningful return to the island and the overall number of gulls nesting at Mono has declined since the ’90s. A recent study surmises that the “missing” gulls are relocating to the San Francisco Bay Area, whose numbers have been dramatically increasing over the same period of time. The current drought is making the situation worse – threatening to once again lower water levels enough to connect Negit to the mainland.
Impact on Ducks
A 1993 Mono Lake Environmental Impact Report estimated that prior to the water diversions about 1 million ducks regularly used Mono Lake as a migratory stop. As fresh water from the lake’s tributaries were diverted, the salinity of the lake naturally increased and with it the bird’s food sources were negatively affected (brine shrimp and alkali flies in particular are major food sources for many birds, especially ducks). The reduction in ducks visiting the lake has been pronounced – today about 1% of the ducks and geese visit Mono Lake as compared to the period before Los Angeles started diverting Mono’s water supply.
The Mono Lake Committee believes that had the lake’s water supply not been diverted the lake would be 37 feet higher than it is today, and, had people not taken action to preserve it, the lake would be 29 feet lower than it is today (which likely means the ecosystem would have been devastated). Thank goodness for people taking action!
Mono Lake conservation gained traction in the 1970s. As a result of the tireless work by the Mono Lake Committee and others, in 1983 the California Supreme Court ruled that the state has an obligation to protect places such as Mono Lake, “as far as feasible.” Then, in 1994 the California State Water Resources Control Board issued a landmark decision that placed restrictions on how much water Los Angeles could divert based on Mono Lake’s water level. This directly led to the lake level rising. While this addressed the Negit Island peninsula issue, it has not fully addressed the situation as a whole. For example, Old Marina Islet just recently became connected to the mainland due to low water levels and has suffered from coyote predation as a result. Regardless, the 1994 decision was a watershed moment, no pun intended. It changed the Committee’s mission from “saving” Mono Lake to “protecting and restoring” the lake. But, clearly, the battle isn’t over.
While the 1994 decision provided assurances Mono will survive, it doesn’t assure it will thrive. The lake’s level hasn’t reached the designated 2014 target level and the recent drought has done further damage (the lake has dropped about 1 1/2 feet in the last year and about five feet since 2010, exposing another 2800 acres of land; it should be said that the recent May rains have been helpful!).
As of May 1st 2015, the lake level was at 6378 feet above sea level, only six feet above its lowest recorded level in 1972. In 1941, prior to the water diversions, it was nearly 40 feet higher. The lake’s target level under the 1994 decision is 6392 feet, 14 feet higher than the May 1st 2015 level.
The rate of increase has been slower than expected. A study conducted in 2010 estimated it would take until approximately 2027 to reach the target level of 6392 feet above sea level. However, if that level is not reached by 2020 – just 4 1/2 years from now – the California Water Board will be convened to determine appropriate next steps. It’s not clear to me what those “next steps” could entail. Most importantly though, once (or if) the 6392 foot target level is reached, water management rules must change to maintain that as the new average (which is real good news to look forward to).
The primary benefits of a much higher water level are twofold. First, the lake will have lower salinity – which leads to a larger number of brine shrimp and alkali flies to feed ducks and other waterfowl. Second, it will be more difficult for land predators such as coyotes to reach the islands – which means more secure nesting habitats for California Gulls. Both of these things theoretically will lead to an increase in Mono’s bird population, bringing it closer to where it used to be.
Aesthetically speaking, the lake is surreal. The photograph in this post is of the Mono Lake tufa. Tufa are limestone towers. These towers are scattered around the lake (the south side contains the most). It takes decades, and even centuries, for the tufa towers to form, which occurs through a chemical reaction between calcium in underwater springs and carbonates in the lake. These towers only form underwater – and should remain underwater. The reason they are now visible is because the water level has dropped so dramatically since 1941.
Sunset at Mono Lake in Lee Vining, California.
Mono Lake is an amazing environmental story. Environmentalists are frequently admonished as zealots that place the environment above human lives. My personal opinion is that, generally speaking, this is partially true. However, the Mono Lake matter shows a different side of this stereotype. Environmentalists compromised and in the process of compromising they worked with the city of Los Angeles to help the city deal with the loss of a meaningful amount of its water supply. Mono Lake is saved to a degree, but is still in peril, and Los Angeles continues to receive water, albeit at a lower amount than before the decision. It is fair to say that Mono Lake environmentalists “won” but the region is still threatened and hasn’t fully recovered. And, it’s not clear that it ever will.
In short, the 1983 and 1994 decisions were a victory for Mono Lake and the environment but much is left to do. Restoration efforts continue and the Committee will continue to take action to enhance stream flows where needed and replant native vegetation to aid recovery, monitor the population of waterfowl, educate the public on the “goings on” and work with the city of Los Angeles on their compliance with the 1994 decision. There’s a lot that needs to happen. If you hadn’t guessed by now, Mono Lake is a cause that is important to me and I contribute to its “restoration and protection.”
Sources for this post include the Mono Lake Committee, environmental impact reports, legal briefs and various other research reports. I’m happy to provide further information on Mono Lake conservation efforts and my sources to anyone interested.