MORGAN CITY, La. (AP) — As the swollen Atchafalaya River neared its crest in Morgan City on Tuesday, residents farther upriver were returning to homes that have avoided a brush with flooding.

A mandatory evacuation was lifted Monday for parts of Butte LaRose even though water levels in the small town west of Baton Rouge were continuing to slowly rise.

Major Ginny Higgins of the St. Martin Parish Sheriff’s Office said roughly one-quarter of Butte LaRose’s full-time residents returned home once the mandatory evacuation was replaced with a voluntary evacuation. Higgins estimated that water has reached about 35 structures, mostly sheds and garages. She wasn’t aware of any homes that are uninhabitable.

“Initially it was a very grim forecast,” she said. “(Water) didn’t get to the levels they were anticipating, which is a huge blessing.”

The Atchafalaya River has been rising since the Army Corps of Engineers opened the Morganza floodway in early May, diverting water from the Mississippi River into the Atchafalaya basin. But there was a guarded sense of relief last week at the southern end of the river as the corps began closing some of the Morganza’s gates.

The Bonnet Carre spillway, northwest of New Orleans, remained open on Tuesday and was pouring fresh river water into brackish Lake Pontchartrain. From there, the water will slowly move into the coastal waters of the Gulf of Mexico.

National Weather Service meteorologist Tim Destri said the river was about at its highest point in Morgan City, an oil and seafood town of about 10,000. The water level there stood at 10.2 feet on Tuesday morning and was forecast to remain around 10.3 or 10.4 feet through June 4.

Morgan City Mayor Tim Matte said the 24-foot floodwall protecting the city was doing its job, but backwater flooding in the area remained a concern.

The region hasn’t emerged unscathed. The flooding has inundated thousands of acres of farmland in Mississippi and Louisiana. Meanwhile, an environmental crisis could be on the horizon in southern Louisiana. The fresh water diverted from the Mississippi River could pose a serious setback for the badly damaged oyster industry, which is struggling to recover from last year’s BP oil spill. Too much fresh water can kill oysters.

So far, the Army Corps of Engineers is confident its flood system will hold up. And it’s performed well so far, though crews up and down the river have had to chase sand boils — where water undercuts the levee and land on the other side seems to boil.