This section includes the Flood Insurance Rate Map (FIRM), prepared and approved by the Federal Emergency Management Agency (FEMA). The Planning Board uses it to designate the areas with a 1% or more risk of flooding in a given year.

In the case of Puerto Rico, the Special Flood Hazard Area (SFHA) is designated with the symbols A, AE, V, VE, AO, A99. It also shows zones outside of the SFHA area which are identified with an X.

In the Estuario de la Bahía de San Juan basin, 14.6% of the municipality of Carolina is prone to floods. In Loíza, flood zones occupy 11.7 % of the area, followed by San Juan with 10.6%, Cataño with 4.73% and Guaynabo with 1.46%.

Areas prone to floods are classified by intensity: high, moderate to low, and high (coastal zone).

Regulations allow for public reviews, appeals, and corrections to flood hazard information that take into account conditions of the land. As with any analysis of this type, there are variations in the estimates of the elevation of the floods and limits of the flood zone.