Vilas Ave.The space between your sidewalk and the curb
is an ideal place for a rain garden. It can infiltrate water that's free from pollution, especially if you don't spread salt.
"The Forestry Section is responsible for planting, pruning and removing trees in the outer terrace."
"Property owners who want to plant, maintain or remove trees in this area must apply for a permit from the Forestry Section. An inspector will visit the site, talk with the property owner and issue a permit when appropriate. Permits are free."
"A variety of ordinances restrict what can be planted in the right-of-way. The Building Inspection Unit regulates shrubbery, brush, weeds and other plant material beyond trees that may be in the right-of-way. They also have ordinances that address trees and other plant material situated on private property that impact, impede or conflict with safe use of the right-of-way. Please call the Building Inspection Unit at 266-4551 with these types of concerns."
Several years ago, I asked Genesis Steinhorst of City Engineering. She said that in theory, a permit is needed for a rain garden. It's mostly so they know what's there--to add it to their database of garden locations. You can call either the number above, or Phil Goebler at City Engineering.
The most important thing is that the City doesn't want view of traffic at intersections obstructed. That means tall plants wouldn't be permitted at an intersection. They could even ask you to remove tall plants on your property that blocked the view of traffic.
In practice, what you do on your terrace is pretty much up to you. Your risk of a fine for planting a rain garden is about zero. Some people plant bushes or even small trees such as pagoda dogwoods.
But the bottom line is you don't want to invest large sums, because the City could always decide to resurface your street or replace a water main. When they use that public space for city purposes, be prepared to kiss your garden goodbye.
Don't forget to call Diggers Hotline.