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Placerville, CA – The El Dorado County Community Development Agency (CDA) has
conducted pH tests of stormwater in the area of El Dorado Trail (near the end of Stage Court)
that have indicated high alkaline levels of up to 12.8. Due to these test results, the County
has placed a warning sign and temporary caution tape at the site. In addition, the County has
placed a temporary fence at the site to further deter the public from coming into contact with
the water. The public should not enter this area.
The water source in question is a seasonal drainage that flows northwest under the El
Dorado Trail where it continues in a northward direction. The tests that have produced pH
levels between 12 and 12.8 are located in an overflow area adjacent to the drainage where
there is ponding. Field measurements conducted farther down the drainage (approximately
200 feet downstream) have produced pH levels of around 7, which are within the normal
range for stormwater runoff (per the Central Valley Regional Water Quality Control Board
(RWQCB) Basin Plan standards). The source of the higher levels of alkaline in the ponding
area is currently being investigated. The County has been in contact with the State
Department of Fish and Wildlife and is working jointly with the RWQCB.
pH measures the acidity or alkalinity of a liquid or substance in liquid. The pH scale ranges
from 1 to 14 with 1 being highly acidic and 14 being highly basic. A pH of 7 is considered
neutral (e.g. distilled water). A pH of 12.5 or greater is considered hazardous according to
Title 22 of the California Code of Regulations. In order to determine the potential harmful
effects of a high pH solution, the type and concentration of the substance or substances in
the water causing the high pH must also be known. Lab results of the high pH water indicate
a composition of predominately calcium hydroxide that is diluted. As this water evaporates
the solid material remaining is predominantly composed of calcium carbonate (limestone).
The County will continue to monitor and conduct periodic testing through the wet weather
season in conjunction with the RWQCB. The County is investigating the source of the high
pH water and is evaluating potential mitigation measures.
For additional information regarding the County’s response to this issue please go to
www.edcgov.us/emd. For questions about the current water tests in the El Dorado Trail area
please contact the Environmental Management Division at (530) 621-5300.
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