This storm sewer infrastructure is typical of what exists in Maricopa, Arizona. Runoff that enters the grate flows directly into a landscaped swale beyond the tan railing. Such swales are all over this area. Some swales do double duty as play or recreation areas.

Where I live in Western Washington, runoff is handled differently: there are storm sewer grates every 50 feet or so in the street gutters. They channel runoff into a system of underground pipes that generally empty into rivers and bays. However, Foster Park in Kent, Washington has a large grass-covered swale, where the Interurban Trail and the Green River Trail intersect.

I took this picture while seated on my recumbent trike.