Answer
Yes, the Rivière des Mille Îles and the Rivière des Prairies are both rivers around Laval. The Rivière des Mille Îles is located in the northwest of Laval, while the Rivière des Prairies is located in the southeast. The Rivière des Mille Îles is a tributary of the Rivière des Prairies, and both rivers eventually flow into the Saint Lawrence River.