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Update: May 2004

Current Massachusetts Regulatory Limit
MMCL = Treatment Technique. Refer to 310 CMR 22.20. ORS has adopted the MCL published by the U.S. EPA.

Federal Regulatory Limit
Under U.S. EPA's Surface Water Treatment Rule, systems using surface water or groundwater under the direct influence of surface water must control turbidity (cloudiness of water). At no time can turbidity go above 5 nephelometric turbidity units (NTU); systems that filter must ensure that the turbidity go no higher than 1 NTU (0.5 NTU for conventional or direct filtration) in at least 95% of the daily samples in any month. As of January 1, 2002 for systems serving greater than 10,000 and (under the Long Term 1 Enhanced Surface Water Treatment Rule) January 14, 2005, for systems serving less than 10,000, turbidity may never exceed 1 NTU, and must not exceed 0.3 NTU in 95% of daily samples in any month (U.S. EPA, 2002).

Basis for Criteria
The MCL for turbidity is based on a Treatment Technique as described above.

Critical Effects
Turbidity is a measure of the cloudiness of water. It is used to indicate water quality and filtration effectiveness (e.g., whether disease-causing organisms are present). Higher turbidity levels are often associated with higher levels of disease-causing microorganisms such as viruses, parasites and some bacteria. These organisms can cause symptoms such as nausea, cramps, diarrhea, and associated headaches (U.S. EPA, 2002).

Cancer Assessment: N/A

Biological Pathogen

Analytical Information
: See 310 CMR 22.20 

Analytical Methods
See 310 CMR 22.20

PQLs and analytical methods may have been updated since this guidance value was last revised. Updated analytical methods for drinking water and their associated PQLs may be found at US EPA Drinking Water Analytical Methods .

Federal Register. January 14, 2002. Environmental Protection Agency. Parts 9, 141 and 142. National Primary Drinking Water Regulations: Long Term 1 Enhanced Surface Water Treatment Rule. Final Rule. (67 FR 1811).

U.S. Environmental Protection Agency (U.S. EPA). July 2002. List of Contaminants and Their MCLs. EPA 816-F-02-013.