Complex sentence: Due to additional annexation west to Highway 407 in 2010, the central section is now entirely within the city, making it technically "Eighth" Line "West" (of Hurontario Street) today.
Split into simpler sentences: Due to additional annexation of lands to the west in 2010, the central section is now entirely within the city. With that being the case, it is actually the "Eighth" Line "West" (of Hurontario St.) today.