The storm surge caused substantial beach erosion
, in some cases completely devastating coastal areas. In
Dauphin Island, approximately 90 miles (150 km) to the east of the point where the hurricane made landfall, the sand that comprised the barrier island was transported across the island into the
Mississippi Sound
,
[88] pushing the island towards land. The storm surge and waves from Katrina also obliterated the
Chandeleur
[89]
Islands
, which had been affected by Hurricane Ivan the previous year. The US Geological Survey has
2
estimated 217 square miles (560 km
) of land was transformed to water by the hurricanes Katrina and
[90]
Rita. >The lands that were lost were breeding grounds for marine mammals, brown pelicans , turtles , and fish , as well as migratory species such as redhead ducks
.[81]
Overall, about 20% of the local marshes were
[81]
permanently overrun by water as a result of the storm.
The damage from Katrina forced the closure of 16
National Wildlife Refuges
. Breton National Wildlife Refuge
[91]
lost half its area in the storm. As a result, the hurricane affected the habitats of sea turtles
, Mississippi
[91]
sandhill cranes
,
Red­cockaded woodpeckers and
Alabama Beach mice
. The storm caused oil spills from
44 facilities throughout southeastern Louisiana, which resulted in over 7 million U.S. gallons (26 million L) of oil being leaked. Some spills were as small as a few hundred gallons; the largest are tabulated to the right.
While most of the spills were contained on­site, some oil entered