Healthy Beach Days

Based on bacteria monitoring at Maine’s coastal swimming beaches, this indicator shows the relationship between total beach days and healthy swimming days.

The number of beach days is based on the length of the Maine Healthy Beaches (MHB) monitoring season and the number of beaches monitored. A beach action day results when monitoring shows bacteria levels above the limits considered safe for swimming, resulting in an advisory being posted. A healthy beach day is a day with no advisory. Maine experienced above average rainfall in the summer of 2012, contributing to a slight increase in the number of beach advisory days. With another rainy summer in 2013, this trend is expected to repeat itself.

When Maine has a rainy summer, as in 2013, stormwater carries bacteria from throughout the watershed to the beach. Fortunately this flush of stormwater dissipates with tidal flushing and more than 90% of resamples, taken the day after an exceedance, find that bacteria counts have returned to safe levels. Some beach managers choose to issue “precautionary rainfall advisories” based on local precipitation levels. An advisory might be triggered by more than one inch of rainfall within 24 hours and then lifted 24 hours after the rainfall ceased (or two full tide cycles). When monitoring finds recurring bacteria problems not correlating with rainfall events, MHB works with local stakeholders to identify potential sources of bacteria and address those problems. This has resulted in numerous success stories, such as recent work in Saco that discovered a residential sewer line that was mistakenly connected to a storm sewer. Correcting this cross-connection, combined with other efforts in the watershed, should result in lower bacteria levels in Goosefare Brook in 2014.

Contact: Colin Clark (207) 441-7419

healthy beach days

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