Right or wrong this is how things have been done for quite a few years, and nothing secret about it. The inter municipal agreement says that the municipalities provide the facilities, not the Library. The Library Board gets to advise the municipality if, for example, they consider the proposed site not suitable for a Library, but the municipality gets the final decision. The Library is a creature of the municipalities and they get to decide how it will be run within the provisions of the provincial Library act.
Stating that this is the way things have always been done isn't an argument. The GVPL has a pretty good thing going. They refused to answer any of my questions about lease cost or budget even though they publicly asked for questions.
They can hide behind the FOI act since they are not a public entity although a public entity grants them space.