The XI/22 decisions of the Convention on Biological Diversity (CBD) at its eleventh Conference of Parties invite parties to integrate the three objectives of the CBD into sustainable development and poverty eradication programs, plans, pol- icies, and priority actions, taking into account the outcomes of the Rio+20 Conference. Based on this ground a Cost Benefit Analysis (CBA) of a proposed new development (establishment of soda ash facility) in the Lake Natron area in Tanzania was carried out to inform decision regarding the proposal. The costs and benefits of this project were compared with that of two other alternatives namely the ―Business as Usual‖ (BAU) and ―Sustainable Ecotourism‖ (SE). The results of analysis showed that at the present levels of soda ash prices and investment costs the benefits of ecosystem conservation outweigh the benefits of soda ash mining. We furthermore argue that Lake Natron is part of an important network of ecosystems and should not be viewed as a separate entity altogether. The Lake’s ecosystem needs to be managed wisely by introducing only livelihood initiatives or de- velopments that are linked to the survival of wildlife which it supports, including the lesser flamingo. Sustainable ecotourism is one of such initiatives. Its benefits spill over beyond the local and national boundaries to beneficiaries at regional and interna- tional levels. We therefore underscore the needs for different stakeholders to share the costs of developing a sustainable eco-tourism industry in the Lake Natron ecosystem. This can be achieved through negotiations with regional and global partners for more resources