Monday marked the 74th day that the structure has remained open.

NEW ORLEANS (WWL-TV)— The U.S. Army Corps of Engineers will begin closing several bays at the Bonnet Carré Spillway starting Monday.

Crews expect to close 10 of the 168 open bays starting at 9 a.m. and expects to have the who structure closed in seven days.

Monday marked the 74th day that the structure has remained open. The corps began operating the Bonnet Carré Spillway on May 10 to relieve stress on the levees protecting New Orleans. It was the first time the spillway has been opened twice in one year.

Crews opened 168 of the structure’s 250 bays over 11 days, using cranes to pull up 20 huge timbers called needles in each bay.

The spillway is designed to ensure a maximum of 1.25 million cubic feet per second is passed through the Mississippi River at New Orleans. Monday, a spokesperson for the corps said that the river had receded below the maximum flow and diversion into Lake Pontchartrain was no longer needed.

The amount of water passing through the spillway peaked May 21 and 22 at 161,000 cubic feet per second. That’s enough water to fill the U.S. Capitol rotunda in about 8 seconds.

The governors of Louisiana and Mississippi say freshwater has replaced brackish water in Lake Pontchartrain and left much of the Mississippi Sound far less salty than usual, killing oysters, hurting fish catches and damaging livelihoods. Both have asked the U.S. Commerce Department to declare a fisheries disaster.

Scientists say freshwater in the sound may have contributed to a high number of dolphin deaths.

Entomologists say the lake’s freshwater was also the hatching ground for clouds of mosquito lookalikes that plagued people along the lakefront in New Orleans, Jefferson and St. Tammany parishes.

The Associated Press contributed to this report.