In the Georgetown-San Gabriel Flood Planning Protection Study, consultants used two flood plain models to assess flood risks: a 100-year flood plain and a 25-year flood plain. But for everyday readers, those terms can be somewhat confusing, according to flood-management officials. Importantly, the terms do not mean that a property within a 100-year or 25-year flood plain will experience flooding once every century or every quarter-century. Rather, the terms tell property owners that they have a 1 in 100, or 1 percent, chance of severe flooding during any given year if they live within a 100-year flood plain or a 4 in 100, or 4 percent, chance of flooding if they live in a 25-year flood plain. Other flood plain models exist, including a 500-year flood plain in which properties have a 0.2 percent chance of severe flooding in any given year, as well as a 10-year flood plain where properties have a 10 percent chance of flooding annually.