It is on the one hand a place of recreation for the inhabitants of Greater Lyon and for those of the Côtière de l'Ain and on the other hand, a zone of protection of fauna and flora: The Island of Miribel- Jonage (the park occupies 22 of the 28,49 km2 of this island) is zone Natura 20002 and the Lake of the Blue Waters constitutes a ZNIEFF of type II3.
The Grand Parc has four main functions: to constitute the source of emergency drinking water of Lyon, to constitute a flood zone in the event of floods which thus protects the agglomeration of Lyons, to constitute a zone of protection of the natural inheritance (with for example the Grands Vernes ), and finally provide a basic leisure function (golf course, nautical base, etc.).