Policy measures and remedies obviously depend on the nature of the environmental pollution: if you want to elicit helpful reactions from RG colleagues, you need to be more specific about what is the key pollution problem. For instance, are you concerned about oil spills, or sewage, or excessive discharge of fertilizers from agricultural exploitations, or industrial waste, or red tides, or what? Each problem will need to be addressed with targeted policies and pollution control techniques.

"Polluter pays" principle

Nigeria is not lacking in policies but in implementation of the policies. What we need is the political will and commitment to implement

"Best" policy measure is subjective and dependent on an evaluation of the range of policy options in light of the peculiar situation of the Niger Delta. The challenges in any regulatory system are multifaceted an often require a complex and multi-pronged approach. In that context, perhaps you want to consider narrowing your question and focus on a particular policy option and explore its utility within the context of the Niger Delta. If it is at all helpful, I have published a few articles on the environmental situation in the Niger Delta.  You may want to see if there are insights you may gain from them. Very best wishes

This is a "million dollar question" relevant not only for Niger Delta but entire Africa where state institutions are weak. President Obama famously said that "Africa does not need strong men but strong institutions". The answer he did not give is how do we build these strong institutions in the midst of "strong" men!.

Laurelta rightly pointed out policies are not lacking - in one of my articles I documented over 30 policies and legislation relevant in the management of the Niger Delta wetlands ecosystem. 

Now to answer your question: The problem of Niger Delta has been too much emphasis on on formal institutions (what Ostrom calls institutions in form), which are completely different from institutions in use. The reason for this is not far fetched - because these formal policies neglect local institutions (including institutions of "strong men"). Yet, the ability of formal state institutions to enforce rules at the local levels (such as in Niger Delta) is very weak, hence it becomes very easy for local informal institutions to undermine formal state institutions (may interest you to know that even state actors responsible for enforcing formal state institutions join in undermining them). Therefore, any policy that will be regarded as "best" must be able to integrate both formal state and informal traditional (local) institutions in such a way that enforcement and punishment will be easier. The good news is that this interaction between state network/institutions and traditional networks/institutions is ongoing on a daily basis - hence can be tapped into.