Since development of wetlands brings external effects, there exist huge social losses if policy maker does not produce the policy, which is to internalizing environmental costs. The ideal way to derive the optimal level of reclamation (or sustainable development) is to make mitigation market for nation level. Finding the optimal level of development for individuals is to start from deriving marginal abatement cost function (MAC) and marginal benefits function (MB) due to creation of wetlands. Market approach is desirable to achieve conservation of wetlands theoretically, there are several constraints to adapt to Korea practically: 1) not enough site acquisition, 2) no obligatory legal system, and 3) funds for initial investment. Therefore, possible policy is needed to play a role for smoothing movement market approach in this situation. The alternative method is a government’s intervention, which is making funds for creation of replacement wetlands from developers. The possible ways to make up funds for carrying out creation of replacement wetland are introduced as follows: 1) imposing creation costs on developer, 2) imposing lost value of wetlands on developer, and imposing tax on developer’s benefit. To apply the above to government policy, it is requested to carry out researches as follows: 1) scientific research for understanding wetlands including physical circumstances and ecosystem, 2) engineering research for development of green techniques relating to creation, restoration, and enhancement of wetlands, 3) economic research for value evaluation and damage assessment of wetlands, 4) research for building a hybrid model combining all research results, and 4) research for reviewing and legislating an obligatory regulation and action plan.