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ATSDR reviewed and evaluated available data related to potential contamination of water from the Blue Lake which supplies potable water to residents located in Sitka. Health assessors drew the following conclusions:

  1. This site is categorized as Hazard Category C: Indeterminate Public Health Hazard. The limited data do not indicate that humans are being or have been exposed to levels of contamination that would be expected to cause adverse health effects from the Blue Lake water supply. However, data or information are not available for all environmental media to which humans may be exposed. If data become available suggesting that human exposure to hazardous substances at levels of public health concern is occurring or has occurred in the past, ATSDR will reevaluate the need for any follow-up.
  2. Adverse health effects are not expected as a result of exposure to contaminants detected in water or sediment samples collected from Blue Lake.
  3. Due to the low levels of dioxin found in the sediments, it is unlikely that exposure to water from Blue Lake would result in any significant exposure to dioxin. The average estimated exposures to dioxin from using water from the Blue Lake supply are substantially less than the MRL; therefore, the potential exposure to dioxin in the water is minimal and these exposures are not of public health concern.


As a result of the review of the available information, ATSDR makes the following public health recommendations:

  1. Continue to review and evaluate environmental data for the site as it becomes available. If data suggest that human exposure to hazardous substances at levels of public health concern is occurring or has occurred in the past, ATSDR will provide recommendations for appropriate follow-up.
  2. Continue to insure that the public water system is adequately monitored on a regular basis as required by the SDWA.
  3. Continue to periodically monitor the water supply for total suspended solids (TSS) to insure that the filtration waiver continues to be acceptable for maintaining an adequately protected and safe water supply for the community.


Based on the data reviewed regarding the Sitka community's municipal water supply, ATSDR concludes that no further ATSDR public health activities regarding the water supply are warranted. If data become available suggesting that human exposure to hazardous substances at levels of public health concern is occurring or has occurred in the past through another media, ATSDR will reevaluate the need for any follow-up.


ATSDR provided an opportunity in the final draft stage of this document for the general public to comment on Agency findings or proposed activities from September 3, 1998 - October 3, 1998. The purposes of this activity were to: (1) provide the public, particularly the community associated with a site, the opportunity to comment on the public health findings contained in the public health assessment; (2) evaluate whether the community health concerns have been adequately addressed; and (3) provide ATSDR with additional information. ATSDR received no public comments during this period.


  1. City and Borough of Sitka, Alaska Public Works Department Water Division. Watershed Control Program, Blue Lake Drinking water Supply. Submitted as part of the Avoidance Criteria of the U.S. Environmental Protection Agency Surface Water Treatment Rule 40C.F.R. 141.71 Safe Drinking Water Act. June 1992.

  2. Keck, D., Mayor City and Borough of Sitka. Ordinance No. 92-1091. An ordinance of the City and Borough of Sitka adding Chapter 15.02 to the Sitka general code creating a watershed control program.

  3. Ecology & Environment (E&E). 1995. Final Expanded Site Inspection Report.

  4. USEPA. October 1991. Final Report - Environmental Evaluation of Pollutants in Sitka, Alaska, Health and Environmental Assessment Section, Environmental Services Division, Region X.

  5. Delta Toxicology, Inc. And Scientific Resources, Inc, 1995. Dioxin in the Sitka Environment: Focus and Findings of Site-Specific and Area Studies Conducted 1990-1995 and Preliminary Interpretation of Health Effects. Seattle, Washington. August 21, 1995.

  6. Foster Wheeler Environmental Corporation. Mill Operable Unit Remedial Investigation Alaska Pulp Corporation, Sitka, Alaska. November 11, 1997.

  7. American Public Health Association. Standard Methods For the Examination of Water and Wastewater, 15-1981, pp 131-2.

  8. City and Borough of Sitka. Report on 1997 Annual Onsite Inspection of City Of Sitka Public Water System To Satisfy Annual Report Requirements for Avoidance of Filtration. December 1, 1997.

  9. Evans, L. City and Borough of Sitka, Public Services. FAX transmission of turbidity data. July 13, 1998.

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