Connecticut’s goal (PDF file) is to eliminate beach closing caused by discharges of untreated or poorly treated sewage, the most common cause of elevated bacteria levels. After rain storms, runoff and overflows from combined sanitary/storm sewers are presumed to contaminate the water, prompting towns to close beaches automatically as a precaution. The Council adds up the number of days that each city and town closes one or more of its public beaches, and calculates an average for each year. Yearly variations are products of rainfall patterns and incidents such as sewer-line ruptures. Dry summers such as 2002 saw far fewer closings. Rainfall, sewage spills and boat discharges led to some beaches being closed for several days in 2006 and again in 2007, almost all in the western half of the state.