A pril on the Grand usually means high-water fishing. Steelhead fishing is usually going well for the first part of April from Grand Rapids up to Lansing. The fish are concentrated at the dams and in the tributaries at this time either getting ready to spawn or dropping back after spawning. Float fishing with eggs or jigs will work good, bottom bouncing with egg imitations or egg sacks, casting or dropping back plugs, these methods will all catch you fish during the month of April.
With the warmer than average winter/spring we have I expect the run to happen fast this year, I highly doubt that the fish will linger around as long as usual. If you are not having any luck in the main stream of the Grand River go and check out the tributaries, these can fish great well into April as long as the water does not get too warm.
If you are into sucker fishing, you can expect this to be a good time to catch suckers in the Grand. They usually congregate up near 6th Street Dam on their annual spawning run, and they are easily intercepted. Floating or drifting eggs, beads, or worms will tie you into good numbers of these fish. Drifting bottom with the same baits will work as well.
Walleye, bass, and pike are closed so if you happen to catch them while targeting other species make sure you toss them back. Check the regulation book for season dates and if you are planning on fishing tributaries make sure they are open before you fish them.