## 1 Introduction
Whether or not the reduction is socially beneficial can be determined through comparing the economic benefits with the costs involved in the reduction. This paper attempts to determine the economic value or benefits of the reduction of SMD by collecting and exploring people's WTP for the reduction. For this purpose, a survey-based economic technique called a contingent valuation (CV) method was adopted, and the results from a CV survey of 1000 interviewees are reported. In South Korea, SMD occurs mainly through three channels. First, waste from the land or riverside flows into the river when heavy rain falls, and then into the sea through the estuary. If the nature of these wastes is investigated, more than 90% consists of trees and grass, although some of it is household waste such as waste appliances, waste plastics, and waste vinyl. It is impossible to identify the polluters in these cases. Therefore, it is difficult to find the polluters and make them pay for the cost of collecting SMD. In fact, the polluters may be ordinary people. The second SMD channel consists of fishing-related waste that is intentionally or accidentally thrown into the ocean. Fishermen's fishing gear, fishing nets, waste nets, Styrofoam for buoys, and feed bins for cultivating aquatic products are flowing into the ocean. In the case of fishing-related waste, fishermen could be charged with SMD collection costs since they are clearly the polluters. However, not all fishermen discharge waste into the ocean. It is not easy to accurately identify the polluters. In addition, in South Korea, fishermen are exempt from various taxes and are given subsidies because their income levels are lower than those of other occupations. Therefore, imposing a financial burden on fishermen is not a very feasible alternative. Third, waste intentionally or accidentally dumped by coastal inhabitants or islanders also flows into the ocean. Likewise, it is not easy to figure out who among these residents has leaked waste,and their income levels are low, making it difficult for them to bear new burdens even if they are polluters. In summary, identifying the causal provider of SMD is not easy and, even if it is possible, imposing collection costs is not socially acceptable. In the end, the central government has no choice but to collect and utilize SMD through the funds raised from taxes paid by the general public. Thus, the framework of this study, which randomly selected 1000 households nationwide and asked WTP questions, was reasonable. This is because the polluters are not economic players such as certain companies, but an unspecified majority of the general public. The effects of SMD belong to the category of negative externalities, which have many other economic effects. The economic effects of SMD are summarized in three ways. First, there is a decrease in tourism income owing to marine environment pollution by SMD. When SMD flows onto the beach, the number of visitors decreases, which, in turn, reduces the income of accommodations and shops near the beach. Second, there is economic damage that occurs to fishermen. SMD caught in a net causes damage to fish catches or fishing nets. In addition, SMD caught in a ship screw can lead to a ship accident, resulting in huge economic losses. The third effect of SMD is a national economic loss due to transboundary pollution. When SMD crosses the border along the current, transboundary pollution occurs, which can cause conflicts between countries. These various economic effects of SMD can affect the public's WTP for reducing SMD. Therefore, in order to control these effects, it was assumed in the study that everything remained in its current state except for the change in the goods to be assessed. The assessed goods presented to respondents in this study reflected a 33% reduction of SMD by 2023 as compared to the business-as-usual (BAU) state, assuming that there are no economic effects on SMD. There are three sections in the subsequent content of the paper. Section 2 reports materials and methods.