Evaluation of the Visibility Criterion of the Massachusetts Sanitary Code for Swimming in Natural Waters

摘要

The Massachusetts Environmental Code contains a four foot visibility requirement for waters designated for primary contact use. This standard may be limiting state, public, and private efforts to expand recreational swimming in the State of Massachusetts. The origins of and the rationale behind the visibility criterion are discerned with an explanation of the motivation for adoption of the requirement. Literature on the factors affecting water safety (including water clarity) is reviewed. However, no quantitative verification of the water safety-water clarity relationship has been presented. Lakes and ponds with and without authorized swimming are compared with regard to their clarity and in terms of the expected percentage failing to meet the visibility criterion. Economic considerations associated with existing and alternative criteria are discussed. The authors conclude that the costs connected with any visibility criterion (short of eliminating the existing criterion) cannot be justified on the basis of improved water safety alone.