LOS ANGELES — Heavy rain this week turned the Los Angeles River flood-control channel into a raging torrent, and with new storms expected on Monday, emergency officials are keeping a wary eye on a well-known stretch that has long been vulnerable to flooding.

Glendale Narrows is a lush 7-mile section of rumbling runoff between Griffith Park and downtown that attracts numerous sightseers and bicyclists. But despite its Instagram appeal, the narrows is a flood manager’s nightmare.

It remains one of the few areas along the World War II-era channel that has a soft bottom due to its high water table. As a result, it is prone to erosion and buildups of sediment, vegetation and debris that could back up flows dumped by major storms.

It is also the only major segment of the 51-mile-long L.A. River flood-control system that was not designed to contain a 100-year flood, or a major deluge that has a 1% chance of occurring in any given year.

To make matters worse, this stretch of river is frequently crowded with weeds and trees.

“Glendale Narrows is a choke point that we watch closely,” said Mark Pestrella, director and chief engineer of the Los Angeles County Flood Control District. “The big problem is that it is under the control of Army Corps [of Engineers}, which is not adequately funded to clean out the area on a regular basis.”

Although it is “armored” with flood barriers installed by the Army Corps to protect surrounding neighborhoods, industrial areas and freeways, major downpours still spark concern among county flood managers.

County officials have proposed taking ownership of 40 miles of flood-control channels still operated by the federal government. By doing so, they hope to expedite maintenance and improvements as climate change increases the frequency of extreme weather.

Such a transfer of authority, however, would require congressional approval. “That could happen very soon,” Pestrella said, “or not for years and years.”

The Army Corps of Engineers has helped reduce the flood risk by removing about 45,000 cubic yards of sediment from the Glendale Narrows area over the last five years, federal officials say.

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