ARTICLE Estimating Benefits of Improving Water Quality in the Largest Remaining Tidal Flat in South Korea Isao Endo & Mark Walton & Sunyoung Chae & Gyung-Soo Park Received: 3 September 2011 / Accepted: 26 January 2012 / Published online: 25 February 2012 # Society of Wetland Scientists 2012 Abstract This study, employing contingent behavior ap- proach, examines the benefits of improving water quality in the largest remaining tidal flat in South Korea. The southern tidal flat of Ganghwa Island, a major stopping point for significant numbers of migratory birds on the Austral-Asian flyway, draws thousands of visitors every month. However, the current water quality, degraded due to pollution, negatively affects ecosystem services that the tidal flat provides for many creatures, including the last remaining populations of endangered black-faced spoonbill. Questionnaire surveys targeting visitors to the tidal flat have been conducted in 2009. Application of the negative bino- mial model has indicated that the total recreational value of the tidal flat is approximately 11.2 billion Korean won (KRW) per year. The annual benefits of improving the water quality by introducing sewage-treatment plants are estimat- ed as KRW 13.4 billion, while the costs of constructing and operating the plants account for less than 3% of the benefits. There is a strong economic justification for investing in the plants to improve the water quality. These findings are useful for policymakers to positively consider public spending in the tidal flat conservation. Keywords Travel cost . Contingent behavior . Value . Tidal flat . Water quality . Ecosystem service Introduction The southern tidal flat of Ganghwa Island, located on the mid-western coast of Korean Peninsula just west of Seoul, provides a number of ecosystem services (Fig. 1). This is the largest tidal flat (approximately 130 km 2 ) on the west coast of South Korea (Choi et al. 2010). People benefit from a variety of seafood and recreational opportunities, and vari- ous creatures, including the last remaining populations of black-faced spoonbill, rely on the continued health of the tidal flat. It is an important staging area of migratory shore- birds on the Austral-Asian flyway exemplified by the more than 20,000 shorebirds which are observed at two large roosts in the area (Won 1989). It is also a significant attrac- tion drawing tourists from across Korea and further afield, and according to S. Kim of the Ganghwa Tidal Flat Center (personal communication, 3 July 2009), every year about 100,000 tourists visit the tidal flat. To conserve this impor- tant habitat, the tidal flat has been designated as a national heritage (No. 419), and the western part of the tidal flat is included as a part of the Ongjin-Jangbong marine protected area (Park 2009b). Water quality of the tidal flat has declined over the years; according to national standards (http://www.nfrdi.re.kr), the current water quality is poor due to excess nutrients and is now classified as Level III, the lowest level, suitable only for industrial use, but not for swimming or recreation (Park 2009b). In terms of chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP), pollution loadings in the watersheds of Han River where the tidal flat is located are the highest on the west coast of the country (Park Electronic supplementary material The online version of this article (doi:10.1007/s13157-012-0282-z) contains supplementary material, which is available to authorized users. I. Endo (*) : M. Walton : S. Chae UNDP/GEF YSLME Project, 1270 Sa2-dong Sangnok-gu, Ansan, Gyeonggi 426-744, Republic of Korea e-mail: isao.endo@fulbrightmail.org G.-S. Park Department of Marine Biotechnology, Anyang University, Gangwha Campus, Incheon 417-833, Republic of Korea Wetlands (2012) 32:487–496 DOI 10.1007/s13157-012-0282-z