I was reading our 2011 Annual Water Quality Report. Trust me, this is one of the driest technical reports to the general public that you are ever likely to read. It’s mailed each year by our East Bay Municipal Utility District (EMBUD). By a sheer coincidence so random I deserve no credit for my discovery, the TV was tuned to a PBS Quest special, “Mercury in San Francisco Bay.”
There’s a hidden danger in San Francisco Bay: mercury. A potent neurotoxin that can cause serious illness, mercury has been flowing into the bay since the mining days of the Gold Rush Era. It has settled in the bay’s mud and made its way up the food chain, endangering wildlife and making many fish unsafe to eat. Now a multi-billion-dollar plan aims to clean it up. But will it work?
So, our San Francisco Bay annually flushes some 3,100 pounds of mercury out through the Golden Gate. Its principal source dates to the early days of the Mother Lode. Several rivers carry those compounds down into the Sacramento River. Mercury is not water soluble, but Methylmercury is. It’s a bacteria-generated trace compound of mercury found in all those waters. Although not normally considered present in hazardous concentrations, methylmercury is accumulated in the tissues of small aquatic animals and fish. Like other heavy metals, it is not metabolized. Smaller fish in turn are eaten by larger fish, and so on and so on, all the way up the predator chain. Sharks and largemouth bass are often too toxic to eat.
So what did I ever find in the EMBUD water quality report about mercury? Nothing! I checked more carefully. The report even cites trace levels of uranium (not mined in our area): the EPA target concentration is 20 pico-curies per liter, or less. All our water sources are less than 1 PCi/L. If EBMUD even lists uranium, why, then, no mercury statistics?
So, I went to EMBUD’s website. Plenty about water quality; a little bit about mercury in fish; nothing about mercury in drinking water.
Yet it’s plainly there. Now, we don’t get our drinking water from the Sacramento. Depending on the city we live in, we get it from the Hetch Hetchy, the Mokelumne, or regional reservoirs. In my area, we get it from the Upper San Leandro and Chabot Reservoirs. I haven’t fished Lake Chabot in years, but many people do.
I found a PDF from the California EPA listing CHEMICALS IN FISH FROM TEN RESERVOIRS IN ALAMEDA, CONTRA COSTA, SANTA CLARA, AND MARIN COUNTIES – INTERIM COUNTY HEALTH ADVISORIES.The report is on “elevated levels of mercury and PCBs” in those reservoirs.
“If you eat the recommended maximum amount of fish from one reservoir, do not eat any other fish during the same month.” For women of childbearing age, and children:
Lake Chabot: Carp (0) OR Largemouth bass (1) OR Channel catfish (4) OR Redear sunfish (4)
How does mercury get in the reservoirs, and what does it mean to we who drink it? The Upper San Leandro reservoir was not listed. Since we get drinking water from the Upper San Leandro and Chabot Reservoirs, I conclude there is a problem in both reservoirs since I have fished and hiked in both recreation areas. They are part of the same drainage.
Humans may not be in the fish foodchain, but we’re at the top of the predator food chain, AND we ingest and cook in a lot of drinking water. I caution the reader again, drinking a glass of water is NOT the same as eating a fish. The fish act as pollutant concentrators (think: toxin storage containers), from small snails to mosquito larvae to minnows and all the way up the chain.
Question of the day: Why is a water-drinking human not like a fish in water, even if we’re vegetarians? And why would EBMUD report on minuscule uranium concentrations, but not on the locally much more serious mercury pollution?
- PBS Quest video (embedded, 11:33)
- EBMUD Annual Report (PDF)
- CHEMICALS IN FISH FROM TEN RESERVOIRS IN ALAMEDA (CA EPA, PDF)
- Methylmercury (Wikipedia)
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