The new artificial Don River mouth is officially full as of Friday afternoon, marking a colossal milestone for the crown jewel in Toronto's $1.3 billion Port Lands Flood Protection Project (PLFP).

The project reached a pivotal stage in early February when crews began to pump water into the serpentine river valley carved through the Port Lands, and pumping activity wrapped on Friday when the river had reached the water level of Lake Ontario.

While many expected the new riverbed to fill in dramatic fashion, the reality is a more gradual process designed to allow aquatic plants to take hold, before the two plugs damming the Keating Channel to the north and Toronto Harbour to the southeast are removed.

The pumps are off! Give or take a few centimeters, the river is full to Lake Level. pic.twitter.com/ug2G9b59pg

— Rocky (@TheRockRipper) February 16, 2024

The public has been kept up to date throughout the filling process, excitedly watching the new river come to life.

Only the circumference of a regular tennis ball left to go! (About 20 cm). The river will likely be ‘full’ by the end of the week, but if you ask me, it looks pretty full already. pic.twitter.com/0J2T6jrpRe

— Rocky (@TheRockRipper) February 14, 2024

As water flowed into the river, the new Villiers Island came into existence, now separated from land on all sides.

The river's water level has reached a depth of 4.5 metres and will continue to be adjusted to match Lake Ontario's water levels until the day the river finally flows through this artificial channel.

Friday Photo: Wait, which body of water is which? On the left side of the photo is one of a series of wetlands in the Port Lands. To right side is the recently flooded river. The new wetlands and river will be an ideal habitat for fish species, as well as other animal species. pic.twitter.com/cZCgG1pM3p

— Waterfront Toronto (@WaterfrontTO) February 16, 2024

Excavation is already underway for the earthen dam dividing the river's current outflow at the Keating Channel with the new river mouth.

A recent update from Waterfront Toronto states that work has begun on "excavating the soil next to the 'west plug.'"

The construction update explains that this plug "is an underground structure just east of the new Cherry Street bridge. Once we excavate the soil next to it, it is the only structure separating the lake from the excavation area. It is designed to hold back the lake water from entering the river valley, much like a dam."

Indeed, Toronto's murky Don River is at a turning point in its life — as an artificial naturalized mouth intends to correct the channelization and straightening projects that permanently altered the river's course during the city's early industrial boom.