|
Watershed Management Bureau
Public Beach Inspection Program
Sample Analyses
EPA's Ambient Water Quality Criteria for Bacteria-1986 suggested states change their standards to reflect the results of research that showed a correlation between high levels of E. coli and Enterococci with swimmer illnesses. The results also specified that E. coli was the most appropriate indicator organism for freshwater,
while Enterococci were most appropriate for marine waters. As a result of these
findings, New Hampshire changed their standards in 1988 to coincide with EPA's
recommendations.
The Beach Program also collects algal samples at beaches in order to identify
possible toxic cyanobacteria. There are certain species of cyanobacteria that
produce harmful toxins that can cause illness in animals, including humans, if
ingested in large quantities, or upon contact with the skin or mucous membranes
(See Health Risks Associated with Toxic Cyanobacteria.)
State Standards
New Hampshire law (RSA 485-A:8) provides standards for the state's water
quality. The standard at freshwater swimming beaches is 88 counts of E. coli
per 100 milliliters (mL) of water in a single sample. The geometric mean
standard for freshwater beaches is 47 counts of E. coli per 100 mL in at
least three samples collected in a 60-day period. The standard at marine
swimming beaches is 104 counts of Enterococci per 100 mL of water in a single
sample. The geometric mean standard for marine beaches is 35 counts of
Enterococci per 100 mL in at least three samples collected in a 60-day period.
When bacteria samples exceed the state standards a beach advisory will be posted by DES or a beach may be closed at the discretion of the town.
|
