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Tunnel removal could make river too salty for farms

Climate change is already posing threats to Richmond's agricultural water supply
Salinity Terborg
Land and water systems consultant, John Terborg, says a study is needed to understand the effect deeper dredging could have on the Fraser River’s salinity. Photo by Graeme Wood. December 2015.

Delta and Richmond farmers are asking regional and provincial officials for help in studying the effects of climate change and the proposed removal of the George Massey Tunnel on the salinity of the lower Fraser River.

“If you take that tunnel out of there you’ll have free flow, and the salt water could be pushed back further up the river,” said Richmond farmer Bill Zylmans, president of the Richmond Agricultural Advisory Committee and a member of the Agricultural Land Commission’s South Coast Panel.

Zylmans explained that the vast majority of Richmond farmers depend on the river for irrigation and salt water coming in from the ocean is detrimental to crops.

Adding to the concern over the tunnel’s removal is climate change and global warming, which will also affect how river runoff behaves during daily tidal cycles.

Last month, the Richmond Farmers’ Institute, in conjunction with the Delta Farmers’ Institute, asked Metro Vancouver to help conduct a three-year benchmark salinity monitoring program and to undertake a study of various scenarios that may affect irrigation water from the river.

Richmond resident John Terborg, who holds a masters degree in land and water systems, has been consulting with concerned farmers and environmentalists on the issue.

Terborg explained that the river has a “salt wedge,” which is the layer of dense ocean water that flows upstream beneath the river’s fresh water outflow.

The salt wedge is primarily influenced by three factors: river flow (discharge), tidal fluctuations (sea level) and channel depth (dredging), noted Terborg.

Climate change is likely to affect the first two factors while the removal of the tunnel would facilitate the third factor.

As the climate warms, there will be less snow and ice melt to feed the river, allowing the salt wedge to penetrate further up the river. This problem will be compounded by rising sea levels, which will contribute to higher salinity in the river. Meanwhile, drier summers will create a greater demand for fresh water.

In addition to those naturally occurring changes is the potential removal of the tunnel.

“We see it as a big blockade (of salt water) in the river,” said Zylmans.

Terborg said presently the river is dredged to 11.5 metres (natural depth is five metres).

“With the tunnel gone, as proposed with the bridge project, it would probably be a little deeper than it would be now,” said Terborg.

Port Metro Vancouver and Fraser Surrey Docks have expressed the desire to dredge to about 13.2 metres in depth, while the Richmond Chamber of Commerce has noted ships may require 18 metres in the future.

The proposed study hopes to assess what kind of salinity the river would experience under various conditions, factoring in river flow, sea level rise and channel depth.

“Any study we do will look to reflect on what those realities would be,” said Terborg, at a town hall meeting in Steveston last week.

He noted that he hasn’t seen much in the way of environmental impact studies for other proposed river projects — such as terminals for LNG, thermal coal and jet fuel — that may require extra dredging.

Zylmans noted a new multi-million dollar irrigation pump in Delta (80th Avenue) built during the construction of the South Fraser Perimeter Highway did not consider how water intake would be affected if or when the river is dredged deeper.

“No one has studied how the river will perform,” said Zylmans.

“There’s a whole bunch of unknowns, so this study will bring a lot of things to light and some of the unknowns will become a little more clearer,” he added.

Terborg said the City of Richmond has monitored salinity at certain points of the river. A solution for southeast Richmond farms may be to draw more water from the north arm.

Of particular concern for Richmond farmers, said Terborg, is how salt contamination is especially harmful to cranberry fields, which abound in Richmond.