What do the flags mean?

Use caution and common sense when making a decision about whether or not to swim at King’s Beach! The flags are not always right. Do not swim if it has rained within the past 24 hours. If the weather has been dry, then swim by Kimball Rd. or Pierce St. to avoid contamination from Stacey’s Brook. 

All of the public beaches operated by the Department of Conservation and Recreation (DCR) must comply with the minimum water quality testing standards as set by the Department of Public Health (DPH). It is important to monitor water quality throughout the summer season at swimming beaches to ensure that water quality is safe for swimming standards. When a water quality test exceeds 104 colony forming units per 100mL of water (cfu/100mL) of the indicator bacteria (Enterococcus) then the beach must be posted as unsafe for swimming. Swimming in water with elevated bacteria levels may lead to nausea, vomiting, stomachache, diarrhea, headache or fever.

Water quality is monitored daily at King’s Beach for recreational swimming throughout the summer season. Daily samples are collected at three sites on the beach: Kimball Rd., Pierce St., and Eastern Ave. in Lynn. A weekly sample is collected at one location in the town of Swampscott which is managed separately by the Town of Swampscott and not DCR. Once the water sample is collected, it is taken to the laboratory facility which has contracted with DCR to facilitate the daily testing. Following the sampling, it takes at least 24 hours for the results to be reported via email to DCR beach operators. When the beach operator then flags the beach as safe or unsafe for swimming, it is based on the prior day’s water quality.

Due to the time delay between when a sample is taken and the results are published, the decision informing which flag to fly on the beach is based on inaccurate information. In the 24+ hours that occur between the two events, at least two tidal cycles have occurred, making entirely new water fill the space. Incorrect flagging raises concern because it is a safety hazard for a beach to be posted as safe to swim when there are elevated enterococcus levels and alternatively, it creates barriers to important recreational resources when a beach is posted as unsafe to swim when the enterococcus levels are below the limit. 

When it rains, water quality decreases due to the storm water runoff into local bodies of water and contaminates them with whatever bacteria or toxins it has picked up along the way. For this reason, it is a good rule of thumb to not swim if it has rained within 24-48 hours. In addition to this, there are particular geographic issues that make water quality testing more difficult at King’s Beach specifically. By Eastern Ave is Stacey’s Brook, a historic waterway which contains bacteria-laden water from both Swampscott and Lynn. Stacey’s Brook has connections to toilets, broken pipes and outdated systems which create a near-constant elevated bacteria count. 

Based on an evaluation of beach water quality data from the prior six years at King’s Beach, Kimball Rd., Pierce St. and the Swampscott location demonstrate safer water quality ratings than Eastern Ave. This makes sense because Eastern Ave is the location closest to Stacey’s Brook. Beach water quality ratings represent the percentage of days which do not exceed the bacteria threshold of 104 cfu/100mL. A higher safety rating indicates more days where the water quality was safe for swimming.