We have a spring that runs all year long that comes from deep in the mountain on our property. It runs down a gully it has formed over the years into a ditch by the road that runs past our house and then down the ditch to a culvert that runs under the road. Where it runs out of the culvert it soaks into the ground and that is the end of its destination. One year it backed up about half way to its destination and the ice was 4-5' deep where it formed an ice dam. The spring is still running so water was running down this big chunk of ice.....which will get bigger!