Thank you, but the leaves are not that shiny!

From your photo, it looks like an ash tree, but it's not close enough to tell. Other possibility is a hickory maybe? Same with the disease issue. Too hard to tell from the photo. But, if it is an ash tree, it's probably Ash Anthracnose. It's warm and very wet in Chicago this year, right? Perfect conditions for this: "Ash anthracnose is probably the most common disease of green ash. It is caused by a fungus and occurs during cool, rainy weather. It can be confused with ash plant bug and herbicide damage. Individual trees vary in their susceptibility to anthracnose to the extent that some trees may be infected every year and others only rarely or never at all. Initial symptoms on green ash include very small (grain of sand-sized) purple or brown spots, sometimes with a cream-colored center, on young leaves. These spots may enlarge and coalesce forming brown blotches. Leaves often become distorted and drop and young shoots may be killed. Defoliation and leaf browning cause homeowners a great deal of concern, but treatment is generally not warranted. Affected trees usually put out a second flush of leaves and make up for lost time later in the growing season. However, trees that have been defoliated three to five years in a row might benefit from chlorothalonil, mancozeb or thiophanate treatment at budbreak to prevent infection. The fungus can overwinter on the ground in infected leaves and twigs, so raking and disposing infected material may help reduce infection the following spring." Your main link didn't work for me -- brought up a screen, but no photos, looks like you have to create an account to view them, and I didn't want to do that. Here is a link that might be useful: Pamphlet where I got the Ash Anthracnose info:

the seed are called gumballs ... and when the tree ages enough.. to start dropping them.. you will not be able to walk barefoot in your yard ... glorious PARK trees.. you better think long and hard about whether your yard is big enough ... also.. known for surface roots ... and suckers.. if you cut a root ... now.. if you just gotta have one.. check out the link ... who cares about all the other problems.. lol apparently i am a bit bipolar on my opinion of these trees.. lol ... oh.. and i forgot to mention.. the heavenly.. aroma of a crushed leaf. but it is very ephemeral.. lasting only seconds ... ken Here is a link that might be useful: pay real money for a variegated one ...

there are all kinds of variations on the theme ... its the thin leaves that are easy to set you on the right track ... and of course.. it standing next to water ... just btw.. they are not good backyard trees .. so just kill that dream .. if thats where you are thinking of going ... ken