If there's any doubt, check the color of your oil on the dipstick and if it looks milky(water contamination) then change the engine oil and filter(several times, usually 3 times with short idling period in between) until the oil looks clear then take the ski to the lake and run it for a good period of time to drive the remaining water out of your crankcase.
Remove the spark plugs and see if there are water droplets on the electrodes.
Your owners manual and shop manual describe the process of water ingestion steps to take.
My guess is you did no harm (in 30 secs) unless the water flow from your flush was quite high, at least you've blown the excess water out of your exhaust system so it cannot back up into your engine. You may have come close, so check you engine oil and plugs for signs of water.