Late in the century, the city began re-routing Tanner Creek and other West Hills streams into combined sewers and filling their former channels and basins to make flat land for homes and businesses.

In the 21st century, Tanner Creek is nearly invisible, flowing through a conduit (but not a combined sewer) that empties into the Willamette at Outfall 11, near the Broadway Bridge.

Lownsdale was the surveyor on an improved version, a plank road, two years later, which began near the future site of the Portland Art Museum.

In 1888, after the Northern Pacific Terminal Company bought the lake, it began filling it with sand and ship ballast.

Investigation of the subsequent sewer reconstruction and repair led to a scandal during the administration of Mayor George Henry Williams and to the firing of the city engineer and chief deputy city engineer on grounds "that they had a part in a general conspiracy to slight the work.

Opened on land acquired in 2003, it is an "urban waterscape" built on fill that rises 20 feet (6 m) higher than the former lake surface.