Update: Helix Water says Lake Jennings drinking water tests clean, issue is with fish tissue; state clarifies problem is with fish tissue, not necessarily water for drinking
By Miriam Raftery
Photo: U.S. Environmental Protection Agency
August 6, 2016 (San Diego’s East County) – State officials are warning that 150 reservoirs statewide are tainted by mercury. Ten San Diego reservoirs are contaminated, including some of East County’s most popular fishing spots. “Mercury is negatively impacting the beneficial uses of many waters of the state by making fish unsafe for human and wildlife consumption,” the State Water Resources Control Board website warns.
However some local officials dispute those findings.
What lakes locally have mercury issues,accordingto the state?
Local reservoirs listed as "mercury impaired" on the state's document are El Capitan Reservoir, Lake Henshaw, Lake Hodges, 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.
Mercury pollution of oceans has also skyrocketed in recent years, raising concerns for consumption of both saltwater and freshwater fish.
What local officials say
Kathleen Hedberg, a director on the Helix Water District Board, says Lake Jenning tested clean for mercury. "As you can see in the link here of our 2016 Water Quality Report there was no detected mercury in our drinking water supply,"she told ECM but added, "We do not test the fish in the lake." Additional information on Helix water quality can be viewed here: http://hwd.com/water-quality-assistant/.
Mark Umphries, director of water quality and systems operations at Helix, confirms,"The focus of this State Water Resources Control Board (SWRCB) program is the mercury content of fish tissue not the mercury concentration in the water. We monitor mercury concentrations in our lake water but the levels are below detection. Fish tissue concentrations can be high even though the mercury concentrations in the water are not detectable." He said they have reached out to the state but don't dispute fish tissue measurements.
We are awaiting responses from the county on its reservoirs,as well as clarifications from the state.
How did mercury contamination occur?
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.That includes air pollution from overseas as well as volcanic contamination.
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 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, 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, guts and organs 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.
Check with your local health department for any fishing advisories.
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