Sat Apr 2023

Mono Lake*

I visited this natural wonder years ago when its water level was at an all-time low, due to excessive water diversion by the City of Los Angeles. (A legal challenge later provided some remedy.)

The rocks in the photo are not in Mono Lake, of course, but right here in Hardy Pond, just south of Smith Point. The white bands appeared for the first time this winter, stirring my memories of the evaporative deposits at Mono Lake. I took the photo on January 9, 2012, during the brief and only appearance this past winter of ice on the pond.

I’ve looked out upon this scene every day for twelve years, but had never seen those vivid white bands before this winter. Through my window, I can still see them now, three months later in March. They may, in fact, have grown wider. They’re visible when the rocks are dry and sun is on them.

We’ve heard several explanations of the recent sunfish die-off, except the 800-pound gorilla in the room: poor flushing of the pond due to the silting of its outlet channel. This narrow, quarter-mile channel discharges to Chester Brook, and ultimately to the Charles River. Is the pond behaving like Mono Lake, building up natural mineral deposits, or toxins, or decaying organic matter (that depletes oxygen in the water), because it has no effective outlet? A testing program could provide answers.

Fish kills due to natural oxygen depletion (anoxia), though common other times of year, are almost unheard of in the spring, according to MassWildlife. Natural oxygen depletion is a seasonal effect, they say, occurring either in winter during prolonged ice cover, or in summer when water temperatures become elevated — but almost never in the spring. There was ice on Hardy Pond for no more than a few days this past winter, so isn’t it reasonable to look for other causes?

The outlet channel remains silted up two years after the great floods of March 2010. This should be a matter of overriding concern. Both water quality and flood control are dependent on a free-flowing channel. This quarter-mile stretch urgently needs to be cleaned out, as an outside engineering study (pdf) recommended late in 2010, and as an earlier study called for in 2002. As of this writing, more than a year after the recent report, little or nothing has been done.

Update, July 2012: As I reported above, I saw the white bands as late as March of this year, but they vanished after the ensuing spring rains.