An apparatus 40 is used for stabilizing a leak in a dam 20, which was built adjacent a body of water 26 to prevent flooding of the water onto adjacent land areas 24a. Leaks in the dam 20 may occur because of a breach 38 developing undesirably in, and possibly through, the dam. The apparatus 40 includes an elastomeric sheet 44, which is wound onto a spool 48, when the apparatus is in a storage-and-handling mode. When the breach 38 is discovered, the apparatus 40 is placed adjacent the dam 20 and the sheet 44 is unfurled into a breach-sealing mode of the apparatus, where the breach 38 is covered and sealed by the unfurled sheet.