University scientists do not typically find short-term projects attractive. Even if these conditions are met, you might still profit from retaining a consulting biologist to help you identify which scientist to select and how to manage his or her work. The alternative to retaining your own scientist is to negotiate with the opposing parties to the disputed action and the responsible agency to sponsor a research project jointly. Before doing this you must judge whether the risks attendant upon yielding control to a heterogenous group are as great as the benefits of having the costs shared and all parties involved in planning and evaluating the research. It is certainly true that the results of such projects are easier for all sides to accept.
Good scientists are often more willing to be involved in such projects.
A positive side effect of joint projects is that they often have the effect of reducing conflict between warring sides. To do things this way, form a joint committee to craft a request for proposals and evaluate the applications. Advertise such requests for proposals as widely as possible, preferably in a professional journal such as Science . If you have no experience managing a proposal process, a consulting biologist should be able to assist you.