This paper addresses the specific benefits and costs for converting coastal wetlands around the Youngsan River in Korea into agricultural use.In conventional benefit-cost analysis (BCA) excluding passive-use values, two scenarios are employed: in Scenario 1 it is assumed that the effects of agricultural production and its air quality improvements occur after 10 years from the beginning of the project.With this optimistic estimate this period is 5 years shorter than the status quo due to the expected technical advances for removing the salt from reclaimed land.Scenario 2 is assumed that the period is normally 15 years without considering the technical changes.The results shows wetland development is preferred to its preservation in Scenario 1,yielding NPV of $ 49,030 thousand at the discount rate of 8 %, and IRR of 8.28 %, B/C ratio of 1.03.In contrast to Scenario 1, Scenario 2 rejects economic feasibility for the development project at the discount rate of 8%, yielding a negative NPV of $271,575 thousand, IRR of 6.5 % and B/C ratio of 0.84.In sensitivity analysis, a change of agricultural production factor is most sensitive to a change of IRR under Scenario 1, while under Scenario 2 the cost factor of fishing rights lost is most sensitive.With an argument of extended BCA including passive-use values, the estimates of IRR are 7.42 %, 5.42 %, and 4.06 % for 1 year-payment, 5 year-payment, and 10 year-payment of passive-use values, respectively under Scenario 1.Under Scenario 2 the estimates of IRR are 5.85 %, 4.25 %, and 3.09 %, respectively.They show that consideration of passive-use in BCA can play a crucial role in reversing the results suffered by weak persuasion for wetland preservation.Further analysis using a goal-seeking model produces the specific minimum magnitudes of passive-use values so as to preserve wetlands in this project according to national level and household level with some different possible discount rates (5%,6 %, and 7 %).If about fifty-eight percent of all households in Korea can have their annual WTP of $ 5 to $16 for preserving wetlands only for 10 years, wetlands would progressively be protected even under the worst scenarios of low discount rates.Finally, this paper provides a direct and intuitive comparison of total wetland preservation value and total development values for agricultural use.The results illustrate that total value of wetland preservation is about three times much higher than that of development for agricultural use, even though this method is quite sensitive to criteria and methods of resource allocation.It is noteworthy that only agricultural use will be less efficient than wetland preservation if the project does not include industrial use of reclaimed lands.