Stormwater retrofits are structural features applied in urban watersheds to help minimize channel erosion, reduce pollutant loads to surface and ground water, and improve aquatic habitat. Retrofits can be big or small, but some type of retrofit is usually possible for most stormwater management situations. Examples include large retention ponds and small on-site water quality treatment facilities. Retrofits should be chosen while keeping in mind cost, pollutant removal capability, and watershed size.