Bruce Petty has a post on his Modeling the Los Angeles River. One thing you will see along both sides of the Los Angeles River are the cast iron drainage covers of all sizes. These swinging iron covers keep the river from back flowing and kids from exploring. The castings have a cat head shape and folks like to draw cat faces on them, they can be seen looking eastward from the I-5 freeway in Glendale. Modeling the Los Angeles River.