Prioritization for Monitoring. The approving authority shall maintain a list of all beaches. The monitoring priority for each area shall be based on frequency and nature of use, proximity of pollution sources, and effects of storm events on the waters. The approving authority shall identify each beach as Tier 1 (High Priority), Tier 2 (Medium Priority), or Tier 3 (Low Priority) and provide appropriate public notification. Bacteriological Monitoring. The approving authority shall perform a sanitary survey before a beach may open. In addition, one or more sampling events shall be performed and completed during the 30-day period before the opening of a beach for public use. Sampling Frequency. Tier 1 — Frequently used beaches or beaches where risk may potentially be elevated by known pollution sources or impacts from rainfall shall be monitored weekly. Tier 2 — Less frequently used beaches or beaches where potential pollution impacts are minimal shall be monitored biweekly. Tier 3 — All other beaches shall be monitored monthly. Evaluation of water quality using Beach Action Values (BAV). Sampling events shall consist of at least three indicator bacteria samples per sampling event. In addition to the application of the BAV, the approving authority may consider other factors, including the results of sanitary surveys, prior rainfall, and other environmental conditions in making public health decisions.