This study explores methods of allocating costs incurring from construction of environmental infrastructure among local governments involved in the project. Principles for equitable cost-allocation are reviewed, and pros/cons associated with different methods are examined. Proportional Allocation method, Shapley Value method, SCRB (Separable Cost-Remaining Benefits) method are applied to a case of swage treatment plant in Gyeongnam province region, Korea. It is found that the SCRB method produces the most equitable result, followed by Shapley method. The Proportional Allocation method, although easy to understand and simple to calculate, is found to be skewed in favor of small town.