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Elevated Mercury Levels in Colorado Fish

DENVER, US - The Colorado Department of Public Health and Environment and Colorado Division of Wildlife are announcing fish consumption advisories for Rifle Gap Reservoir, Elkhead Reservoir, Juniata Reservoir, Catamount Lake and Lake Granby due to elevated mercury levels detected in fish tissue samples collected at the reservoirs.

The fish tissue testing is part of an ongoing five-year sampling plan of approximately 120 water bodies in the state. These postings follow state laboratory results on fish tissue samples completed on 33 additional water bodies in 2008. More than 112 water bodies now have had laboratory testing completed as part of the study.

According to state officials, routine sampling indicated at least one fish of the species sampled at Elkhead, Rifle Gap and Juniata reservoirs and at Granby and Catamount lakes met or exceeded the mercury action level of 0.5 parts per million set by the state health department. All species and sizes of fish with mercury levels in their tissue greater than 0.3 parts per million are considered in these advisories.

Mercury poisoning can affect humans of all ages. However, pregnant women and children under age 6 are especially susceptible, because mercury can harm developing nervous systems in fetuses and young children. Adults exposed to high mercury levels also can suffer from central nervous system and cardiovascular problems.

Occasionally, as in the case of Juniata, a water body that serves as a drinking water source will require a fish consumption advisory. Drinking water that might contain small, trace amounts of inorganic mercury does not pose a health concern. The concern is when inorganic mercury is converted to organic mercury through the food chain.

Insect or plants may absorb some of the inorganic mercury, turning it into organic mercury that then can be consumed by fish. As larger predator fish eat other small fish, the mercury amounts in fish tissue accumulate. The health concern occurs when these larger fish are consumed by humans. When humans ingest inorganic mercury in small trace amounts in water, it is not significantly absorbed in the body.

Each fish consumption advisory includes consumption recommendations in three categories: for the general population; children aged 6 and younger; and women who are pregnant, nursing or who may become pregnant. The following fish consumption advisories provide advice on limiting certain species and sizes of fish to a certain number of meals per month. A meal is considered to be 8 ounces for adults and 4 ounces for children. [Detailed advisories are found at the end of this release - and provided as attachments.]

The main source of mercury in Colorado water bodies is air deposition - mercury in the air being deposited in lakes, streams and reservoirs.

the Fish Site Editor

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