We like to go every spring during the large shorebird migration. We usually go in May, but this year we went a little early because we were already up that way. I'm glad we did, because I've never seen the water levels so high! It was impressive to see flooded marshes extending for miles on both sides of the road. There was one part of the road that was even submerged under about 6 inches of water.
We did the 12 mile auto tour loop, which is a dirt road that drives around the wetlands. We saw a lot of our old favorite birds, including American white pelicans, great blue herons, double-crested cormorants, sandhill cranes (a personal favorite), white-faced ibis, American avocets, Western grebes, cinnamon teals, and hundreds of American coots (always lots of those guys). We even saw a new life-lister, the Great Egret. I wish I had a camera to get a better picture of it.
We didn't hit up the visitor center because the boys were sleeping, which I feel like happens every time we go there. One day I'll go inside.
Here is a link to the website, which details when the roads may be closed: https://www.fws.gov/refuge/Bear_River_Migratory_Bird_Refuge/