.. depending on how many fish have already bedded/spawned, how many are still in the process, how long the water stays high & stable, and the water temp/clarity. Timing is everything to the spawn ... and that goes along with water levels, water temps/clarity, and available cover in the preferred depth.
Flooding waters can cover a bed with too much water depth, or dirty water, and negate those spawning attempts. It can also flood back into areas that are difficult for anglers to get to, and allow spawners to complete their mission without being found (IF the water stays long enough for the process to be completed).
Normally ... it's not a good thing ... but, it does depend on when, during the spawning period, that it occurs. The worst aspect of this scenario, is when the water comes up high, then is dropped back down, rapidly. This lessens the chance for the ones already bedding, to complete the process (due to the extra depth of water) ... and pulls the water off the newly made beds, that may have been made by the late comers that followed the rise into the newly flooded areas.
The fish can wait on the proper, preferred water temps & clarity ... and even extend the egg dropping process over a couple of weeks ... but, they can't control the rise/fall of the water level. If conditions were suitable for a long enough period, to allow some spawning to take place (before the flooding) ... it only takes two to three days for the eggs to hatch into fry. As long as the water temps don't drop too drastically, once the fry are viable, they should be able to survive (for the most part).
Mother Nature is a smart 'ol gal :p ... and that's why the fish develop so many thousands of eggs, knowing that only a small percentage will have a shot at making it (surviving) past the conditions and the predators ... but, none would have a chance, if the fish only produced a small number of eggs. It's a fish eat fish world, down there, and the addition of undesirable water conditions/levels only adds to the decimation.
... cp