SR 109 heads north concurrent with SR 15 and SR 65, in downtown Ottawa. The route heads through the north side of downtown Ottawa as a two-lane highway with a center turn lane, passing through a mix of residential and commercial properties. The concurrency curves northeast and has a traffic signal at the northern end of the SR 15 concurrency, SR 15 heads northwest and the other two routes continues northeast. The concurrency end when SR 109 turns due north and SR 65 continues northeast. The highway passes through residential and commercial as a two-lane highway, before leaving Ottawa. The route passes through farmland, with some houses, and curves northeast.