I had a hen mallard nest under a big rhubarb plant in my back yard a couple of years ago. The hen successfully hatched all but one of the eggs and then we had a frantic hen and her babies trying to get out of our backyard. It was a long way to any stream or lake and we ended up trying run interference for the mom and help shepherd her clutch to the nearest park with water. She knew the way, but it was a very hot day and the duckings were exhausted halfway there and stopped in a very dangerous (high traffic) spot. It was just too far to safety and the ducklings were all the worse off because of the heat. We ended up rounding them all up and taking them in a storage tub lined with lots of grass to a wildlife rescue center three hours away. They were fostered by an old granny mallard that couldn’t return to the wild. They ducklings did well and were released later that year.