Wednesday, May 23, 2007

Mono Lake, California

Have you ever visited someone's house, only to find no answer when you knocked on the front door? Of course you have. Did you go one step further, perhaps going around back to see if anyone was there? And, instead of finding the person you were hoping to meet, you were surprised to find...a yard full of heaps of trash and rusting junk!!

Wouldn't your opinion of that person change somewhat?

Mono Lake
N38.004 W119.011

Well, replace "someone" with the City of Los Angeles, and the "backyard" with Mono Lake. I don't think I can visit that city again without thinking about how it has trashed the ecosystem of Mono Lake, its "backyard" 300 miles away. Mono Lake is nearly 3 million years old. But it has been brought close to the brink of collapse in less than the span of one human life.

Mono Lake is one of the most productive lakes in the West, teeming with plants and animals that have adapted to its salty, alkaline waters. This abundant aquatic life makes it one of the most important wetlands in the entire western hemisphere for migrating and nesting birds.

60,000 California gulls--80% of the state's population--return to Mono Lake every spring and summer to nest and raise their young. Historically, over a million migratory birds, representing 100 different species, used Mono Lake as a stopover point on travels as far-flung as the Arctic and Patagonia.

Mono Lake has a simple food chain. Bacteria provide nutrients for algae, which are eaten by alkali flies and a unique species of brine shrimp that evolved over thousands of years to thrive in the lake's harsh chemistry. The shrimp hatch by the trillions here each year, providing food for millions of birds.

In 1941 the City of Los Angeles extended its aqueduct system into the Mono Basin, diverting water from four of the six mountain streams that feed Mono Lake. As a result, the lake lost more to evaporation than it gained from inflow. Over the next 40 years the lake lost half its volume, doubled in salinity, the surface dropped nearly 50 vertical feet. Miles of newly-exposed lakebottom created dust storms in the windy basin region. The fragile lake ecosystem was given a powerful blow; local wildlife and fisheries, migratory birds and humans all suffered.

A simple food chain is a vulnerable one. As salinity increases, the shrimp and alkali flies become less and less productive. If the environment changes too much or too quickly, the brine shrimp could become extinct. Were that to happen, huge flocks of birds could starve.

As lake levels declined, much wetlands habitat was lost. Without that habitat, the number of migratory birds stopping here has declined greatly.

Tufa towers exposed by the receding surface of the lake.
When freshwater springs rich in calcium bubble up through carbonate-rich lake water, a reaction follows, creating vertical towers of calcium-carbonate deposits called "tufa".

In 1978 a coalition of citizens' groups challenged the legality of the water diversion. Five years later, the California State Supreme Court ruled that there had been a violation of the doctrine of Public Trust, whereby "human and environmental uses of Mono Lake...deserve to be taken into account." In 1990 the court ordered the LA Department of Water and Power to abide by Fish and Game Code laws to protect fisheries in the creeks below the diversion points, and the State Water Resources Control Board began work on a management plan for Mono Lake.

A lake was here, once.
N37.94180 W119.02657

In 1994 the Board decided that the lake must be raised to an elevation of 6,392 feet above sea level, which could take 20 years. This is 19 feet higher than the lake's level in 1994, but still 25 feet below its level when the diversions began in 1941. The next step is to develop and implement a restoration plan for the Basin's streams and wetlands.

Friday: Panic at Panum Crater

1 comment:

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