A large swath of southern San Luis Obispo County was ordered to boil its drinking water last week after bacteria was discovered in Lopez Lake’s water distribution pipeline. Residents of Arroyo Grande, Grover Beach, Pismo Beach, Oceano, Avila Beach and other unincorporated areas of the South County had to to boil drinking water for up to four days depending on where they lived. … The county discovered the bacteria at five routine testing sites in the Lopez water distribution system on April 29. After a second round of tests, the county issued a boil water notice on April 30 — which lifted for some residents on May 2 and others on May 3. … On Thursday, the county shared additional details of what led to the unprecedented boil water notice for Five Cities residents. Here’s what happened.

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• County of San Luis Obispo: News release: Boil water notice summary and next steps