A recent Environmental Protection Agency study has reaffirmed what many have long argued--that anyone who falls into the Charles River by some mishap should quietly accept the University Health Service's anecdote: a tetanus shot.

The EPA report, released last week by the agency's New England regional office, indicates that none of the surveyed 81 miles of the Charles River meet EPA's class B standards of suitability for fishing or swimming.

In a sense the Charles is not alone: the report shows that Massachusetts has the lowest percentage of rivers fit for fishing or swimming in New England.

Only 357 out of the surveyed 1399 miles of river in the state--26 per cent--meet class B standards, according to the annual study, which EPA began last year.

About 51 per cent of the major stem and tributary mileage in the six-state region meet the fishable-swimmable standard with Rhode Island's 64 per cent leading in New England.

However, the EPA predicted that by 1983, 25 of the assessed 81 miles of the Charles--31 per cent--will meet the fishable and swimmable standards, while the state waters complying will almost triple in seven years from 26 per cent to 69 per cent.

The effort to clean up the Charles led two months ago to the fencing off of the north bank of the Charles between Plympton St. and the Anderson Bridge during construction of a relief sewer extension.

Plans call for the construction--and the fence--to move to the other side of the Anderson Bridge in the early fall.