Black Rock

Cohasset, Massachusetts

Black Rock beach is a stretch of rocky shoreline just South of Boston Harbor, named for the two small islands called Black Rocks just off shore of the coastline. It is located off of Summitt Ave and Jerusalem Road. The Beach separates the ocean from Straights Pond, which is a tidal pond flowing into the Weir River in Hingham. There is street parking on Wadleigh Park Rd, but no life-guard on duty so swim at your own risk.

WATER QUALITY
  • Passed water quality tests at least 95% of the time
  • Historical Status
  • This status is based on the latest sample, taken on . The Swim Guide - Massachusetts updates the status of this beach as soon as test results become available. These results were posted to Swim Guide on at
For water quality icon legend, click:   
MONITORING FREQUENCY

Black Rock is sampled weekly from May 20th to September 1st

SOURCE INFORMATION

Local boards of health, county department of health, and the Massachusetts Department of Conservation and Recreation monitor beach water quality in Massachusetts. The monitoring seasons is May through September. Beaches in Cohasset are tested on a weekly basis on Tuesday. The water quality results are posted by Thursday.

Infrequently used beaches or beaches that historically have had very few, if any, water quality issues are tested less often, while high-use or historically problematic beaches are tested more often.

The water at marine beaches is tested for the presence of Enterococci, a group of bacterial species typically found in human and animal intestines and are therefore present in sewage. Enterococci is also referred to as indicator organisms. Indicator organisms are used to predict the presence of pathogenic, or disease-causing, organisms associated with fecal contamination.

Swim Guide checks for the latest information daily, Monday - Friday during the swimming season (May through September).

A beach is marked Green when less than 104 units of Enterococci / 100 ml of water is present in a single sample, or when the geometric mean of 5 samples contains less than 35 units / 100ml of water.

A beach is marked Red when more than 104 units of Enterococci / 100 ml of water is present in a single sample, or when the geometric mean of 5 samples contains more than 35 units / 100ml of water.

A beach is marked Grey when there is no current or reliable monitoring information available.

WATER QUALITY GRAPH

Black Rock

Cohasset, Massachusetts

WATER QUALITY
  • Passed water quality tests at least 95% of the time
  • Historical Status
  • This status is based on the latest sample, taken on . The Swim Guide - Massachusetts updates the status of this beach as soon as test results become available. These results were posted to Swim Guide on at
For water quality icon legend, click:   

Black Rock beach is a stretch of rocky shoreline just South of Boston Harbor, named for the two small islands called Black Rocks just off shore of the coastline. It is located off of Summitt Ave and Jerusalem Road. The Beach separates the ocean from Straights Pond, which is a tidal pond flowing into the Weir River in Hingham. There is street parking on Wadleigh Park Rd, but no life-guard on duty so swim at your own risk.

MONITORING FREQUENCY

Black Rock is sampled weekly from May 20th to September 1st

SOURCE INFORMATION

Local boards of health, county department of health, and the Massachusetts Department of Conservation and Recreation monitor beach water quality in Massachusetts. The monitoring seasons is May through September. Beaches in Cohasset are tested on a weekly basis on Tuesday. The water quality results are posted by Thursday.

Infrequently used beaches or beaches that historically have had very few, if any, water quality issues are tested less often, while high-use or historically problematic beaches are tested more often.

The water at marine beaches is tested for the presence of Enterococci, a group of bacterial species typically found in human and animal intestines and are therefore present in sewage. Enterococci is also referred to as indicator organisms. Indicator organisms are used to predict the presence of pathogenic, or disease-causing, organisms associated with fecal contamination.

Swim Guide checks for the latest information daily, Monday - Friday during the swimming season (May through September).

A beach is marked Green when less than 104 units of Enterococci / 100 ml of water is present in a single sample, or when the geometric mean of 5 samples contains less than 35 units / 100ml of water.

A beach is marked Red when more than 104 units of Enterococci / 100 ml of water is present in a single sample, or when the geometric mean of 5 samples contains more than 35 units / 100ml of water.

A beach is marked Grey when there is no current or reliable monitoring information available.

WATER QUALITY GRAPH



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