A FEASIBILITY EVALUATION OF THE TOTAL MAXIMUM DAILY (POLLUTANT) LOAD (TMDL) APPROACH FOR MANAGING EUTROPHICATION IN SOUTH AFRICAN DAMS Report to the WATER RESEARCH COMMISSION by Dr WR Harding DH Environmental Consulting (Pty) Ltd WRC Report No. 2245/1/15 ISBN 978-1-4312-0673-5 April 2015 Obtainable from Water Research Commission Private Bag X03 GEZINA, 0031
[email protected] or download from www.wrc.org.za DISCLAIMER This report has been reviewed by the Water Research Commission (WRC) and approved for publication. Approval does not signify that the contents necessarily reflect the views and policies of the WRC nor does mention of trade names or commercial products constitute endorsement or recommendation for use. © Water Research Commission Roodeplaat Dam (Gauteng, South Africa) on 28 November 2014. With 62% of South Africa’s largest dams eutrophic or hypertrophic (Matthews 2014) the need for nutrient attenuation interventions is long overdue. Catchment-based audits of nutrient generation, such as the Total Mean Daily Load (TMDL) protocol provide a means of identifying and prioritizing load reductions. EXECUTIVE SUMMARY Total Maximum Daily Loads (TMDLs) are (i) a calculation of the maximum amount of a pollutant that a waterbody can receive and still meet water quality standards, and (ii) an allocation of that amount to the pollutant's individual sources. The TMDL protocol was developed in the USA in support of the Clean Water Act of 1972. TMDLs can be applied to any pollutant, inter alia bacterial, pathogens, suspended solids, sediments, trace metals and nutrients. The TMDL approach can be applied to both lentic and lotic waters.