Onondaga Creek Flood Damage in Syracuse

Why does Onondaga Creek flood Syracuse homes more than before?

The city attributes higher flood risk on Onondaga Creek to lower channel capacity from sediment and to more intense short-duration storms. Both factors mean a creek-side home can take water in a storm that once would have passed without reaching the house.

Sediment settles in a channel when the flow slows, and over time it reduces the space the water can use. A channel with less space rises sooner in a storm, and the water reaches the low ground along its edge at a lower flow than before. The city names both of these causes, sediment and short-duration storms, as the reasons its flood risk on the creek has grown.

Short intense storms add to the problem because they deliver a large volume of rain in a short time. The ground does not absorb it, the channel cannot carry it and the water moves over the low ground in a few hours. A house that was never flooded in a long, slow rain can take water in one of these storms.

What did the 2016 FEMA maps change for Syracuse homes?

FEMA's 2016 maps expanded the Special Flood Hazard Area on Onondaga Creek in Syracuse by 175 acres and added hundreds of residential and commercial structures to the regulated floodplain. A property that was not on a map before may now sit inside one.

The Special Flood Hazard Area is the part of the floodplain that carries the highest chance of flooding in a given year, and the maps set the rules for building and for certain insurance purchases. A structure on the map is regulated differently from one off it, and the local floodplain rules apply to the work.

A homeowner who wants to know whether a property sits on the map should look it up on the FEMA flood map service and on the city's floodplain page. The city's page lists separate maps for Onondaga Creek, Harbor Brook, Ley Creek, Meadowbrook and Onondaga Lake, so the map for one property may differ from the map for the one beside it.

How is creek water different from a broken pipe?

Creek water is contaminated and comes from outside, while a broken pipe usually delivers clean supply water from inside. The difference changes the protective equipment, the cleaning, the removal of materials and the way the insurer looks at the claim.

Creek water has picked up soil, leaves, animal waste, fuel and whatever else sits in the street and the yard. Porous materials that it touches, such as carpet, pad, the paper facing of drywall and some insulation, usually cannot be cleaned to a safe standard and are removed.

A broken supply pipe is different. The water starts clean, and in many cases the hard surfaces can be cleaned and dried in place. The crew records the source at the first visit, because the source decides the treatment and the insurer will ask about it.

What should a Syracuse homeowner photograph after a creek flood?

Photograph the water line on the walls, the silt on the floor, the entry point and the damaged rooms before anything is moved. Dated photographs help the insurer, the crew and the floodplain office understand the event.

The water line is the most useful record. Mark it with a pencil and a date on a wall that will be dried anyway, and photograph it with a reference object for scale. Photograph the window well, bulkhead or door that let the water in, and the yard above it.

Keep the crew's readings, the list of removed materials, the invoices and the letters from the insurer in one place. If the home is on a FEMA map, keep the map panel number too, because it shows which rules apply to the rebuild.

• Dated photographs of the water line on each wall
• Photographs of the silt on the floor before cleanup
• Photographs of the window well, bulkhead or door where the water entered
• The FEMA map panel number for the property, if it is known
• The crew's readings and the list of materials removed

Can a creek-side basement be rebuilt after a flood?

A creek-side basement can usually be dried and rebuilt, but the work is shaped by the floodplain rules, the condition of the foundation and the materials that must come out. The city's floodplain page is the starting point for those rules.

After the drying is complete, the wall and floor finishes can be replaced. Choose materials that tolerate water where the basement is wet at times, such as masonry and concrete in place of paper-faced drywall at the lowest wall. A plumber or electrician should check any system that sat in the water before it is put back in use.

Rules for rebuilding in a floodplain are set by the city and by the map on which the property sits. The city's floodplain page is the place to start, and the office that handles those permits should be asked directly which steps apply to a particular property.