In 1968, a causeway was built between the municipalities of Moncton and Riverview. Immediately after the construction was completed, the causeway proved to be problematic, severely undermining the health of the river. However, it took until December 2016 for provincial and federal government representatives to permanently solve this problem by announcing the transformation of the causeway into a partial bridge. Why have governments taken so long to act? Using the Multiple Streams Approach (MSA) and relying on unpublished documentary and interview data, we argue that the coupling of the problem, politics, and policy streams was only possible once the window of opportunity created by the election of Liberal governments in Fredericton and Ottawa in the mid-2010s had been opened.