Fish near mine have heavier gonads
Authorities to monitor for adverse effects with release of Con Mine waste water
Meagan Leonard
Northern News Services
Friday, March 20, 2015
SOMBA K'E/YELLOWKNIFE
Pollution may not be good for the environment but male stickleback minnows might not mind.
A recent report prepared on behalf of Miramar Mining Corporation, owners of the now defunct Con Mine, finds that male ninespine stickleback - the most abundant fish in waters downstream of the mine site - have heavier gonads than other populations when mine waste water is released. They also showed greater liver weight.
Smaller fish in Baker Lake were found in 2012 to be larger than other raising concerns about the effects of discharge from Giant Mine on Arctic grayling spawning in the creek. Another study, this time on effluent from Con Mine, found heavier gonads on ninespine stickleback. - photo courtesy of Paul Vecsei |
A similar phenomenon was noted in 2012 when sticklebacks and juvenile and female slimy sculpins from Baker Creek, downstream of Giant Mine, were larger than specimens upstream from the mine at the Yellowknife River.
Both sites are former gold mines. Water from Baker Creek has been shown to have arsenic concentrations 23 to 35 times than those set out by the Canadian Water Quality Guidelines. The Con Mine report states in the past, effluent from the mine "was characterized by elevated levels of metals and ions which are occasionally toxic to fish.
"Toxicity is expected to decrease when discharge resumes due to lower volumes of treated effluent," the report states.
Adverse effects on fish is something environmental authorities will be monitoring closely with the latest discharge of accumulated mine waste water due to be released in August - the first such release in four years.
In years where no waste water was released from the mine, these effects seem to have been reversed, according to the report.
Currently, only surface runoff is being treated at the site, stated Scott Stringer, the site general manager at Con Mine, in an e-mail. However, the company will begin treating underground water in 2016. A new water treatment plant scheduled to be in operation later this year will help accommodate this additional discharge.
"The new plant is scheduled for commissioning mid-2015. It's designed to treat surface and underground water to meet our water quality effluent discharge," said Stringer.
The water is drained through the Meg/Keg/Peg lakes, eventually reaching Great Slave Lake. Environment Canada media relations officer Melanie Quesnel says at this point they are unsure exactly what caused discrepancies in the study findings.
"It is not yet understood why there are differences in fish organ size between earlier and later studies," she said. "It is difficult to predict what the results may show in the upcoming study and this is why environmental effects monitoring studies are done on a regular basis."
After operations ceased at Con Mine in 2005, mine closure activities have been conducted to minimize the environmental impact of the site, including: removing leftover chemicals, draining and capping tailings ponds to prevent groundwater contamination and stabilizing toxic waste. Water monitoring and treatment will be ongoing in the area for approximately 25 years with discharge volumes continuing to decrease. There was no discharge in 2009 or from 2011 to 2014 and volume this year is also expected to be low, hopefully reducing the symptoms of toxicity, the report states. Environmental studies in the area began in 2003 with a focus on monitoring the growth, reproduction, survival and condition of fish, along with water and sediment quality.
Marc Casas, a regulatory officer with the Mackenzie Valley Land and Water Board, says this type of analysis is mandated by federal regulations in order for a company to maintain its water licence.
"If you discharge over 50 metres cubed of effluent, you have to adhere to these regulations," he said. "Con Mine does and so they've been doing these different phased studies."
This work helps determine if the waste water is affecting aquatic wildlife in receiving bodies of water, said Quesnel.
"Environmental effects monitoring provides information on the effects of mine effluent on fish, fish habitat and fish use," she explained. "The results from this monitoring help inform decision-making with respect to the regulations."
She said they will also help provide guidance for rehabilitation plans at the site. "If a rehabilitation program is developed by a proponent, the results from the study could be used to inform it."
Weledeh MLA Bob Bromley says although he is not an expert on the Con Mine file, these types of mine contaminants have the potential to be a concern if not monitored closely.
"(Contaminant) levels are extremely high in the area of Con Mine, not surprising given the decades of mining and fallout and low emission standards at the time," he said. "We know the phenomenon of bioaccumulation can concentrate those contaminants even further in animals and fish leading to a public health concern."
Greg Robertson of Bluefish Services, which runs fishing tours on Great Slave Lake, says he has not noticed any adverse effects from the discharge.
"Most of my fishing is from 15 to 50 km to the east of Yellowknife so I have not noticed any effect in the past," he said.
