Microbial risk assessment for recreational use of the Kranji Reservoir, Singapore

The Public Utilities Board of Singapore is responsible for management of the Kranji drinking water reservoir and wishes to open the reservoir for recreational water use as part of their "Active, Beautiful, and Clean Waters Programme". A field campaign was conducted at the Kranji Reservoir to determine the microbial water and sediment quality of the reservoir for use in a model that predicts the risk of gastrointestinal illness due to recreational use of the reservoir. Water samples were collected at seven locations throughout the reservoir and sediment samples were collected at two locations located near the shore. The samples were then analyzed for Enterococci concentrations using a most probable number method. The measured geometric mean concentrations found during the field campaign were 13.3 Enterococci colony forming units (CFU) per 100 ml water and 1400 Enterococci CFU per gram sediment. Based on the strengths and weaknesses of available statistics-based risk models, a model by Wiedenmann was chosen based on the flexibility of the model and the quality of the underlying epidemiological study. Using the model, no-observed-adverse-effect-level guideline concentrations of 25 Enterococci CFU per 100 ml for swimming, 51 Enterococci CFU per 100 ml for kayaking and 860 Enterococci CFU per gram sediment for wading were calculated. Based on all available bacterial measurements of the Kranji Reservoir, an interim geometric mean guideline of 25 Enterococci CFU per 100 ml water and 860 Enterococci CFU per gram sediment is suggested.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Civil and Environmental Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2009

Author dc:creator

• Dixon, Cameron Chaffee

Advisor dc:contributor.advisor

• Peter Shanahan.

• Civil and Environmental Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/51567

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/51567