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Restoring a Nova Scotia River with Liming

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Lewis Hinks - ASF Regional Director for Nova Scotia Lewis Hinks - ASF Regional Director for Nova Scotia

The Nova Scotia Salmon Association is maximizing the benefits of the U.S. Clean Air Act by giving a river that is home to endangered wild Atlantic salmon in southern Nova Scotia continuous doses of lime.

The U.S. Clean Air Act has helped curb  emissions of sulphur dioxide (produced by coal and oil-burning industries) and nitrogen oxide (from vehicle exhaust) that travel on prevailing winds, and fall as rain or snow, driving up acidity levels of distant rivers and damaging fish.  While some areas are recovering, other regions, like eastern Canada and Maine, are still struggling with high acidity levels in their rivers and streams, a problem that could last another 70 to 100 years.

“The granite rock geology in Nova Scotia’s southern uplands region is very slow to repair the soils needed to neutralize acidic water.  Liming now can improve conditions in our rivers until the environment is restored naturally,” said Lewis Hinks, Director of Regional Programs in Nova Scotia for the Atlantic Salmon Federation, a partner in the liming program.

In 2005, West River near Sheet Harbour, located 60 miles northeast of Halifax, became the first test river for using cutting-edge technology imported from Norway to counteract the impacts of acid rain.  One of more than 50 Nova Scotia rivers that are victims of decades of acid rain degradation, this once prolific salmon river was closed to fishing in 1999 after centuries of supporting a vibrant sports fishery.  

Sheet Harbour’s doser is an automated system that draws in river water, combines it with powdered limestone, and releases it further downstream.  Acidity is measured on a pH scale.  A lower number on the scale means greater acidity.  When a river’s pH reading drops to 5.4, Atlantic salmon reproduction begins to fail.  At 4.6 or below, salmon reproduction is impossible.  The doser is programmed to respond to the river’s acidity levels, providing a consistent 5.5 pH reading or better, regardless of the seasonal water fluctuations.

Since the lime doser’s installation, water in the river’s test sections has been between a pH of 5.5 and 7.   Mr. Hinks continued, “Acid-related mortality of wild Atlantic salmon is nearly zero in the limed sections of the river, and juvenile salmon (smolt) production is increasing.”

Edmund Halfyard, a PhD candidate in Biology at Dalhousie University, leads the research.  He has monitored smolt production in both limed and unlimed sections of the river since 2007, two years after liming began.   Between 500 and 1500 smolt are produced annually in the unlimed sections.  In the limed sections, during the first three years of monitoring, the number of smolt ranged from 1900 to 2800.  The production rose to 7,200 smolt in 2010 and in 2011, an astonishing 11,700. 

Mr. Halfyard said, “Because of the complexity of the acidity problem and its impact on West River’s salmon populations, we are getting just a glimpse of what is happening.  It does appear though that liming is having a positive impact on the river and its fish populations.”


The Atlantic Salmon Federation is dedicated to the conservation, protection and restoration of wild Atlantic salmon and the ecosystems on which their well being and survival depend.  ASF has a network of seven regional councils (New Brunswick, Nova Scotia, Newfoundland and Labrador, Prince Edward Island, Quebec, Maine and Western New England).  The regional councils cover the freshwater range of the Atlantic salmon in Canada and the United States.


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Comments (7 posted):

littledavid123 on 27/02/2013 10:36:08
Well that is certainly encouraging. Dave
noreaster on 27/02/2013 10:53:49
Cool story. Good to hear it is working.
sandfly on 27/02/2013 11:53:27
several streams around here have that done and we now have wild brookies again in them. Babb Creek Watershed Association -- Lycoming County -------------------------------------------------------------------------------- 2010 Winner Babb Creek had been polluted by acid mine drainage for over 100 years and has negatively affected the Pine Creek below the town of Blackwell. Local residents formed the Babb Creek Watershed Association and through partnerships with DEP, DCNR, the Arnot Sportsmen, and many other supporting organizations, undertook 18 separate projects with a combined budget of nearly $8 million. The group managed operations of a large one-of-a-kind water treatment facility which uses a byproduct from limemaking to treat a very large volume abandoned mine discharge. Through their efforts, five miles of Pine Creek and 14 miles of Babb Creek have been removed from EPA’s list of impaired waters and the creek now supports a thriving trout fishery.
fredaevans on 27/02/2013 15:44:50
Fascinating read! Totally new topic to me. fae
wt bash on 27/02/2013 15:55:58
The NY DEC has been liming a few of the lakes up in the ADK quite a while now. http://www2.dnr.cornell.edu/ext/fish/trout/Liming.pdf
zum on 01/03/2013 20:11:28
Liming of different systems isn't nothing new,been going on for years...20+ The legal introduction of smallies and the illegal introduction of chain pickerel we be another nail in the coffin for our brookies and salmon.Our waterways are small and alot are all connected directly.Between the bucket biologests,barley tolerable waters and fishing pressure....it's going to be a struggle for our natives to survive. I'm blamming this snow I'thats falling right now for this post.
cincyspey on 06/03/2013 03:34:19
i can hopefully see this river this summer...will be fishing for brookies up there.
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