Generally speaking, Chicago area trees require one inch of water per week when in leaf, either from rain or via the garden hose. Move the hose periodically to cover as much of the root zone as possible. Better yet, use a soaker hose, which can water a greater area of the root zone and does not need to be moved as often. Believe it or not, over-watering is a big killer of trees. When the tiny air passages between soil particles fill with water, roots cannot extract oxygen.
Trees can literally drown.
Check the soil to make sure watering is necessary. If the ground is moist, don't water.