Notes from the Field: Harmful Algal Bloom Affecting Private Drinking Water Intakes – Clear Lake, California, June-November 2021

Details

• Journal Article:
  Morbidity and Mortality Weekly Report (MMWR)
• Personal Author:
  Carpenter, Catherine ; Little, Amy ; Paulukonis, Susan ; Ryan, Sarah ; Solomon, Gina M. ; Stanton, Beckye
• Description:
  During June-November 2021, multiple cyanobacteria harmful algal blooms (HABs) occurred in Clear Lake, the largest freshwater body of water located entirely within the state of California. During this period, measured chemical concentrations of microcystins (a class of cyanotoxins produced by cyanobacteria) in the water of the Lower and Oaks arms of Clear Lake were persistently above the California recreational "Danger" health advisory level of 20 µg/L. A maximum microcystin detection of 160,378 µg/L was measured at a beach in the city of Clearlake in September 2021. Microcystins are potent hepatotoxins and can cause gastroenteritis, dermatitis, and allergic reactions. The 17 local public drinking water systems with source lake water intakes in Clear Lake monitored and managed their systems with frequent testing, adjustment of treatment, and other measures to ensure that microcystins in finished drinking water did not exceed the Environmental Protection Agency (EPA) drinking water health advisory of 0.3 µg/L. However, an unknown number of homes around Clear Lake relied on private water systems with lake water intakes or wells, and the quality of the private drinking water at those homes was unknown. To address this uncertainty, the California Water: Assessment of Toxins for Community Health (Cal-WATCH) project collected and analyzed tap water samples for cyanotoxins from households with private lake water intakes and private wells located ≤50 ft (15.2 m) of the lake. To identify potentially eligible homes, parcel maps of lakefront land were overlaid with built structure and water system boundary maps of all 17 local public drinking water systems. Staff members from the Big Valley Rancheria Environmental Protection Department visually inspected the shoreline by boat to identify potential lake water intakes. A total of 493 parcels with structures that were not within the boundary of any public water system or that had a visible lake water intake were identified. Outreach to homeowners included postcards, door hangers, and knocking on doors. Broader community outreach was also conducted via social media and local earned media. [Description provided by NIOSH]
• Subjects:
  Climate Change Community Health Services Environmental Exposure Hazardous Substances Microbiology Occupational Health Safety
• Keywords:
  Bacteria; Water sampling; Drinking water; Microorganisms; Environmental health; Community health; Toxins; Climate change
• Series:
  Weekly Report: Morbidity and Mortality Weekly Report (MMWR)
• DOI:
  https://doi.org/10.15585/mmwr.mm7141a3
• ISSN:
  0149-2195 (print) ; 1545-861X (digital)
• Publisher:
  Centers for Disease Control and Prevention (CDC) (U.S.)
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Journal Article
• Place as Subject:
  California ; OSHA Region 9
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  2 pdf pages
• Contributor:
  Balletto, Alfred ; Schrade, Katherine ; Tyler, Alix ; Laco, Joseph ; Neset, Kris ; Ruiz, Andrew ; Sabogal, Raquel ; Kennedy, Karola ; Chang, David ; Nogueira, Isadora
• Volume:
  71
• Issue:
  41
• NIOSHTIC Number:
  nn:20067160
• Citation:
  MMWR 2022 Oct; 71(41):1306-1307
• Email:
  gsolomon@phi.org
• Federal Fiscal Year:
  2023
• Performing Organization:
  University of California, Berkeley
• Peer Reviewed:
  False
• Start Date:
  20050701
• End Date:
  20250630
• Collection(s):
  Morbidity and Mortality Weekly Report (MMWR) National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:778a57a18293aee8c4e85eebf740c7522121f26a431d017675517c14c9a8754a92139396e70414def26040f6e76f3a2ca33736543bb37a0e2f3f020dbca4dd6c
• Download URL:
  https://stacks.cdc.gov/view/cdc/248491/cdc_248491_DS1.pdf
• File Type:
  [PDF - 78.00 KB ]