Flooding is a natural occurrence caused by heavy rain.

If it rains hard enough or long enough, low-lying areas are at risk of flooding.

Flooding does not necessarily mean problems with the storm drainage system. Drainage systems, including storm drains, pipes, ditches and creeks, are designed to hold a specific amount of storm water.  

A flash flood occurs when the amount of rainfall overwhelms our natural and man-made drainage systems or low-lying areas. Generally, one inch of rain per hour will cause flash flooding.

Extra water has to go somewhere There is a limit to how much water our creeks can hold. If enough rain falls in a short amount of time, creeks naturally overflow onto the floodplain.  Floodplains are designed by nature to flood. For that reason, floodplains are part of a healthy creek system.

Rain-swollen creeks naturally overflow onto the floodplain

Development doesn't cause flooding but can make flooding worse
Although flooding is a natural occurrence, man-made changes to the land can also be a factor. In cities and suburbs, pavement and rooftops prevent some rainfall from being absorbed by the soil. This can increase the amount of runoff flowing into low-lying areas or the storm drain system. And eventually, that excess runoff flows into our creeks.

While flooding cannot always be prevented, the risks can sometimes be reduced. Storm Water Services:

• installs and maintains storm drain pipes to reduce street and house flooding
• removes blockages from stream channels  
• updates floodplain maps to show risk along major creeks
• regulates construction in floodplains
• maintains a flood notification system for local emergency responders. 

Drainage and flooding problems
 
Flood preparedness
 
Flood safety
 
Why everyone should be concerned about flooding

Presentation about flooding on Little Hope Creek

Why is this house wearing stilts? (U.S. Geological Survey's explanation of how flood risks can increase when more land is paved over)