The City currently maintains 144 ponds, 85 miles of ditches and 27 vacant lots reserved for future ponds. To keep storm water ponds and ditches functioning properly they require monthly maintenance. The maintenance includes grass-cutting, pond spraying of invasive vegetation, Fence repairs, sediment dredging, removal of illegal dumping and trash pickup. Storm water ponds and ditches are designed to collect rainwater from impermeable surfaces such as parking lots, roads and buildings. Rainwater is absorbed into the soil helping prevent flooding and improve the water quality in the aquafer, river and bay. Maintenance is a key part needed to help keep the city above water.