The Environmental Protection Agency (EPA) has estimated that a potential gap between future needs and current spending for wastewater infrastructure of $150 billion to $400 billion could occur over the next decade. A number of entities are involved in planning, financing, building, and operating this infrastructure. Some of these stakeholders have suggested a variety of approaches to bridge this potential gap. One such proposal is to establish a clean water trust fund. In this context, GAO was asked to (1) obtain stakeholders' views on the issues that would need to be addressed in designing and establishing a clean water trust fund and (2) identify and describe potential options that could generate about $10 billion in revenue to support a clean water trust fund. In conducting this review, GAO administered a questionnaire to 28 national organizations representing the wastewater and drinking water industries, state and local governments, engineers, and environmental groups and received 22 responses; reviewed proposals and industry papers; interviewed federal, state, local, and industry officials; and used the most current data available to estimate the revenue that could potentially be raised by various taxes on a range of products and activities. GAO is not making any recommendations. While this report identifies a number of funding options, GAO is not endorsing any option and does not have a position on whether or not a trust fund should be established.