You need to be quite explicit about your concerns and the evidence available. Some issues will arise because of loss of amenity (e.g. recreational use of waterways) or because of specific management issues (e.g. is our site management policy working?). This is part of your risk management. You need to think clearly about the issues and they way they contribute to the "problem" and then use this information in defining the "problem" as an essential step in the process. This understanding leads to your hypothesis, which is the basis of your design for the program.