BURLINGTON, N.D. — A fish kill in the Des Lacs River in northern North Dakota appears limited to the river’s lower reach and is probably not a threat to the larger Souris River into which it empties.

Dead walleye, northern pike, perch and other fish were discovered floating in the water and strewn along the riverbank in the Burlington area this week. State health and wildlife officials investigated.

Testing on Wednesday indicated a lack of oxygen in the water was the culprit, Health Department water quality specialist Joe Nett told the Minot Daily News (http://bit.ly/2crFpRR ). The low oxygen is due to low water levels this summer.

“There’s been relatively no runoff this year,” said Chad Zorn, manager of the Des Lacs National Wildlife Refuge upstream. “Rain events have not been significant, nothing major. Water here has sat near or below objective levels all summer.”

There have been no reports of dead fish at the refuge.

The Des Lacs empties into the Souris River at Burlington. The Souris loops into and out of north central North Dakota from Canada. Testing of the Souris found acceptable levels of dissolved oxygen.

“At least at this point, there doesn’t appear to be any effect on the Souris with what’s going on in the Des Lacs,” Nett said.

Officials will continue to monitor.

Information from: Minot Daily News, http://www.minotdailynews.com