U.S. Border Patrol agents are turning their attention to drainage systems around the Valley as smugglers are using them to move people and drugs into the country, officials say. 

Over the span of two days, Border Patrol officials say agents apprehended 23 migrants inside Valley water drainage systems. The latest investigation on Oct. 4 resulted in agents finding nearly 400 pounds of marijuana stashed inside Hidalgo County drainage tunnels.

While officials say there hasn't been a large surge of drugs or people smuggled through drainage systems, there has been some concern. 

"Apart from the odorless gasses, the water being released," Border Patrol agent Jesse Moreno said. "One could get lost, and also it is filled with bacteria and viruses." 

Authorities urge residents to report suspicious activity at 800-863-9382.