The plans for the fusion of Leerdam, Zederik, and Vianen were known since 2015. The municipalities Leerdam and Zederik belong to the province Zuid-Holland where Vianen is located in Utrecht. This led to uncertainty to which province de Vijfheerenlanden would be merged.
In 2016 the task of the merge was assigned to the province of Utrecht because of slow progress. The reclassification presented by the province of Utrecht meant that the Vijfheerenlanden would be part of Utrecht. This to the dissatisfaction of Zuid Holland and Zederik.
Because the provinces couldn’t agree they gave the minister Ronald Plasterk the task to decide. Meanwhile, the municipalities signed an agreement of their merge and collaboration waiting on the result to which province they would be classified.
Geert Jansen, the advisor tasked with the assignment proposed a plan for the merging with Utrecht. This proposition was accepted by the Eerste Kamer and Tweede Kamer in 2018. Making the merging with Utrecht definitive on 1 January 2019.
Bad news for the cartographers keeping border information up to date. Laren and barium have indicated that they also want to merge to Utrecht. They see nothing in the plans of the merge with Huizen which would mean they would stay part of Noord Holland. This would cause future difficulties for the collaborations of the BEL municipalities. This could lead to a new border change favorable for Utrecht.