The City-Parish of Lafayette is located in southwest Louisiana, approximately 40 miles from the Gulf of Mexico. The normal annual precipitation averages 54-58 inches. The oil industry plays a vital role in the parish economy, yet the area remains diversified, depending greatly upon agriculture and distribution of retail and wholesale trade.
The Vermilion River is the major waterway that winds its way through Lafayette Parish, and is the area’s major stormwater drainage outfall being fed by Bayou Carencro, Bayou Queue de Tortue, Beau Basin, Coulee Bend, Grand Avenue Coulee, Coulee des Poches, Coulee Ile des Cannes, Coulee Mine, Francois Coulee, Gaston Coulee, and the Isaac Verot Coulee. The Vermilion River passes near several communities and across the Intracoastal Waterway before it empties into Vermilion Bay, which connects the Gulf of Mexico. According to the USGS, the flood stage of the Vermilion River at Surrey Street is approximately ten (10) feet.
During high flood stages, an unusual phenomenon occurs on the Vermilion River. When the river below Pinhook Bridge is unable to carry high flows, the direction is reversed upstream toward the low marsh areas east of Lafayette Parish. This reversal is limited to the reach between Pinhook Bridge and Long Bridge where the left descending bank borders a low swamp area. When the stages downstream of Pinhook Bridge are relatively low, the direction of flow is in the normal downstream direction.
Significant floods are reported to have occurred as early as 1907. Other significant floods occurred in 1927, 1940, 1946, 1947, 1953, 1955, 1959, 1961, 1964, 1966, 1969, 1971, 1977, 1993, 1995, 2001 (Tropical Storm Allison), 2004, 2012, & 2016. The most severe flood in the area occurred in August 1940, and studies of this flood showed extremely heavy rainfall at the Lafayette Airport daily rainfall station. For the four-day period of August 6-9, a rainfall of 27.33 inches was recorded; for the 10-day period of August 1-10, a rainfall of 37.86 inches was recorded. To view a listing of Lafayette Parish historical rain events click here: https://www.ncdc.noaa.gov/stormevents/
Rainfall amounts ranged from about 12-26 inches in the Vermilion River Basin over the duration of the event. The Vermilion River crested at 17.62 ft on August 15, 2016.