What lakes locally have mercury contamination?
Local San Diego reservoirs with high mercury levels are El Capitan Reservoir, Lake Henshaw, Lake Hodges in Escondido, Lake Jennings, Loveland Reservoir, Lower Otay Reservoir, Lake Morena Reservoir, San Vicente Reservoir, Lake Sutherland, and Sweetwater Reservoir, according to a California Water Boards publication released in June.
How did mercury contamination occur in Lake Hodges?
Although mercury occurs naturally in the environment, concentrations of mercury exceed background levels because of human activities. Gold and mercury mines and atmospheric deposition are the predominate sources of mercury, with minor contributions from industrial and municipal wastewater discharges and urban run-off.
State and Regional Water Board staff is developing a statewide water quality control program for mercury that will include: 1) mercury control program for reservoirs; and 2) mercury water quality objectives including other bodies of water such as rivers, bays and estuaries, many of which are also contaminated.
Mercury poisoning symptoms
Consuming high levels of mercury can cause mercury poisoning. Immediate symptoms include numbness in the hands or feet, weakness, and narrowing your field of vision. But eating too much tainted Lake Hodges fish can also cause long-term and subtler effects from low dosages of mercury.
Unborn babies and young children are especially sensitive to mercury. If a pregnant woman east too much contaminated fish, her infant can suffer mental impairment and be slow to develop language skills.
How much is too much?
The U.S. Environmental Protection Agency (EPA) recommends consuming a daily maximum of 0.1 micrograms of mercury for each kilogram of your body weight.
Growing children pregnant or breastfeeding women, and women who may become pregnant should be most careful to limit how much fish they eat each year.
However, it is important for pregnant and nursing mothers to eat some fish, since they contain Omega fatty acids that are essential for healthy brain and vision development in babies. Fish with high omega-3 levels good for developing babies’ eyes and brains include trout, salmon, sardines and anchovies.
The California Department of Public Health recommends that if you catch your own fish in coastal waters, lakes, reservoirs rivers or streams, children under age 6 should eat no more than 3 ounces a week, while women may consume up to 8 ounces (weight before cooking).
If you buy fish from a store or restaurant, children should have no more than 6 ounces a week, or 4ounces of canned chunk light tuna, or 6 fish sticks. Women may have up to 16 ounces of fish from coastal waters, or 2 six-ounce cans or chunk light tuna, or one six-ounce can of chunk light tuna a week.
Which fish are safest and most dangerous? How can I reduce my risk and still enjoy fishing?
Never eat swordfish (poor swordfish as this is one of the tastiest and tangiest fillets from the sea), tilefish or king mackerel, since they have the highest mercury levels, the U.S. Food & Drug Administration recommends.
Large fish, especially those that eat others, tend to have the highest mercury levels. While fishermen like to boast of catching big fish, smaller fish are safer to eat.
In lakes, bass are often the top predators and thus most apt to accumulate mercury. In oceans, sharks have the highest mercury levels.
Rainbow trout and smaller sunfish such as bluegill are usually the least contaminated.
Eat only the fillet, or meat, of the fish. Throw away skin, fat, head, where mercury concentrates.
Avoid raw fish or shell fish. If you eat crab, avoid the green mush known as crab butter.
If buying tuna, pick chunk light canned tuna, which has less mercury than white or albacore canned tuna or tuna steaks.
Broil, grill or steam fresh fish on a rack, then discard drippings.
Fish in a variety of locations and eat small portions of different types of fish, rather than large portions of a single species.
Here are more resources on how to reduce your risk of mercury poisoning from fish consumption:
Fish Consumption Advisories and Other State Programs to Address Mercury
Safety Tips for Women and Children
General Health Advice for People Catching and Eating Sport Fish in California.
The California Department of Public Health and the Office of Environmental Health Hazard Assessment are educating people who eat local fish, about the types and amounts of fish that are safe and unsafe to eat.
Plans to control mercury in California reservoirs
The state is working on plans to control mercury in reservoirs where possible, to change fish species stocked at reservoirs with mercury issues, and to post warning signs among other actions. Read more about the mercury control programs:
Statewide Mercury Control Program for Reservoirs Introductory Fact Sheet (June 2016 Fact Sheet).
Draft Summary of Proposed Statewide Mercury Control Program for Reservoirs (May 2016) and List of Mercury-Impaired Reservoirs to be Included in Phase 1
For more information on mercury sources in California, an explanation of how mercury accumulates in the food chain, and an analysis of factors affecting methyl mercury accumulation in reservoir fish, refer to our Fact Sheet (2013 Fact Sheet).
Total Maximum Daily Loads for Mercury in California Waters
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Submitted by Tom Lemon on Sun, 08/07/2016 - 11:15
You can buy test kits sold on Amazon.
You can also buy purified or distilled drinking water at many grocery stores.