Pella Strand is twenty-nine years old, five feet four, and has spent more time underground in the past six weeks than most people spend in a lifetime. She is a municipal surveyor employed by the Works Office, trained in civil engineering at Bobington Polytechnic, and she has been mapping a river that nobody knew existed until she found it.

The Lower Conduit — as the Historical Preservation Society has taken to calling it, after a reference in a 1793 journal — runs beneath the Docklands from somewhere near Harrowgate Pier to the River Ashwater. It is brick-lined, arched, roughly two metres wide and one and a half metres tall, and it carries flowing water. The brickwork is dated 1782, carved in mason’s marks that Strand has catalogued in her survey notebooks.

She has traced 780 metres. Her full report is due at the end of March. She is not finished.

The Junction

On Thursday, working with a two-person support team and chest-high wading boots, Strand discovered something new: a junction.

Approximately 340 metres from the Ashwater outfall beneath Bramblegate Steps, the conduit splits. One branch continues northeast toward the known terminus — the stone-arched outfall that emerges beneath the old commercial wharf, partially silted but still flowing, with the ferry now operating above it. That branch is fully mapped.

The other runs west-northwest, beneath what is now the Bramblegate Market district. Strand followed it for approximately 90 metres on Thursday before the roof height dropped below safe working clearance and she turned back.

“The brickwork at the junction is the same age as the main channel,” she said. “Same mason’s marks, same mortar composition. This was built as a system, not extended later. Someone in 1782 designed a network.”

The western branch appears to be heading toward the old brewery district — an area between Bramblegate and Midtown where three breweries operated from the 1770s to the 1890s, all of which required substantial water supplies. Strand believes the conduit may have been purpose-built to channel freshwater from a spring source to the breweries, with the eastern branch serving as the overflow to the Ashwater.

The Surveyor

Strand joined the Municipal Works Office three years ago, directly from the Polytechnic. The subsurface hydrology survey that led to the conduit’s discovery was her first solo project — commissioned by Chief Municipal Engineer Dorothea Kinnear as part of routine infrastructure assessment, six months before Strand found anything unusual.

“I was checking for flooding risk,” she said. “I was not expecting to find a river.”

She works with a tape measure, a compass, a waterproof notebook, and a modified surveyor’s lamp that she wears on her forehead. Her survey notebooks — she is on the fourteenth — contain not just measurements but sketches of brickwork patterns, water flow calculations, and careful notes on the quality of mortar at different points along the route.

“The mortar tells you more than the bricks,” she said. “It tells you when they were careful and when they were in a hurry.”

The Connections

The Lower Conduit has already intersected with two other stories. The outfall beneath Bramblegate Steps sits directly below the wharf now serving as the southern ferry terminal — and the wharf pilings were placed to avoid the conduit channel, proving that whoever built the wharf knew the waterway was there.

More recently, Dr Annalise Fenn-Coulthard of the Bobington Institute of Natural Sciences has suggested that the conduit’s freshwater outfall may be creating the cooler, fresher micro-habitat on the mudflats that attracted the colony of harbour seals — the first in the lower Ashwater since 1891.

And Dr Emmeline Furness, assessing the Meredith letters discovered at the old Harker Street warehouse, has found a pen-on-linen drawing showing the original quay layout with a “water channel” running beneath the eastern grain shed — almost certainly the Lower Conduit, drawn from memory by someone who watched it being built or knew someone who had.

The Municipal Heritage Committee is considering a formal heritage listing. Strand’s full survey report, due at the end of March, will determine the conduit’s total extent and structural condition.

“Somewhere under this city, there is a river that nobody named,” Strand said when she first described the discovery. Six weeks later, the river has a name, a history, and a map. She is still drawing it.