The Animas RiverOn August 5, the US Environmental Protection Agency accidentally released a large pu

The Animas RiverOn August 5, the US Environmental Protection Agency accidentally released a large pulse of mine waste pollution into the Animas River, a tributary of the San Juan River that eventually reaches Lake Powell. Here is a photo of the Animas River from the USGS: you can even see residual iron in the river. The iron deposited along the river side clearly suggests long-term damage from the August spill, right?I just tricked you. Click for more to learn how.The hidden detail? This is the Animas River where it joins with Cement Creek in Western Colorado, but this photo was taken long before the spill in August. This photo was actually taken in 1997. The problem that led to the Animas River spill in August is a multi-decade problem.After the spill in early August, you heard many reports stating how 3 million gallons of material were spilled. In fact, my original post played this game too – I gave units because they were a “big number” but I violated one of my own pet peeves in science writing – I didn’t give any context for those units. You can see our original post at this link: http://tmblr.co/Zyv2Js1rYLYZc.3 million gallons seems like a lot of water. It’s a huge number. There are now lawsuits being planned by the local population against the EPA for the damage done to this river. But does that big number mean the river is forever spoiled? How does that amount of pollution compare to the pollution in the river on an everyday basis? Those are questions I want to address in this post.The Animas River drains the area around Silverton, Colorado, right at the heart of the Colorado Mineral Belt. There are literally dozens of mines in this area, each of which has taken material that used to be in the ground and exposed it to oxygen; the recipe for creating acid mine drainage.The last major mine that was operating in the area was the Sunnyside Mine. While it was in operation, water that was pumped from that mine was sent through an active treatment facility; however, that mine shut down in 1991 and starved the treatment facility of funds. It closed by 1996.When that treatment facility was shut down, the Sunnyside mine was also plugged to reduce the water flow. Within a few years, the natural system responded and water flows began increasing at other mines including the Gold King Mine. The flow rate at the Gold King Mine alone reportedly reached >200 gallons per minute by the early 2000s, and several other mines from the same complex also began flowing with 300 gallons per minute of mine drainage at about the same time.A bit of math will show that a 300 gallon per minute flow rate from a mine produces 430,000 gallons per day of water flow; in other words, the 3 million gallons spilled in the August spill represents about 1 week’s flow of water from 1 of several mines in this region. Although the mustard color was dramatic, a “sudden spill of a week’s worth of water” sounds a lot less traumatic than 3 million gallons…but even that’s an incomplete story because that’s only talking about volume.To really understand a spill like this the actual units we need to talk about are concentration. If the material that was spilled was 1000x times as concentrated as normal mine waste, then the spill still will look like a huge disaster.The EPA monitored the composition of the downstream water after the spill and was able to see it directly appear in their sampling. The pH of the Animas River dropped to around 4.5 as the spill passed from its normal level close to 7…but Cement Creek, the channel carrying the iron in this photo, had a pH of ~4.08 all the way back in 1997. Although I can’t compare every single pollutant, the copper concentrations in Cement Creek in 1997 were also larger than those measured in the Animas River after this spill.The Animas River is a larger system than Cement Creek, with typically ~3 times the volume of water, so changing its pH does require a large pulse of water, but the chemical analyses of these waters to me strongly suggest that the scandal in this case isn’t the spill itself, it’s what is allowed to flow into that river on a normal day.Downstream, the spilled material flowed into the San Juan River and entered Lake Powell. The San Juan River is regularly monitored for water flow and quality – in that case they measure the total amount of material dissolved in the water and don’t distinguish it by which element is present (a much quicker analysis). On August 11th the conductivity of the San Juan River tripled in a single pulse – likely the arrival of that plume. However, that wasn’t even the biggest spike of dissolved solids in that river this summer, let alone over the last several years. The San Juan River regularly receives pulses of dissolved compounds from both upstream mines and farms depending on rain and water flow rates that are even more intense than this pollution pulse.In this case – dilution was simply winning. The spill had a significant volume, it will leave a mark on the river system, but its volume and the concentration of contaminants is small compared to what drains from these mines during a normal year.This spill should be, more than anything else, a reminder of the toxic legacy of the mines in the Mineral Belt. In this one hill there are a half dozen or so mines continuously leaking acid mine drainage and dissolved metals into Cement Creek. That creek itself is basically permanently dead. Nothing can live in it. The EPA was working on this mine and contributed to the plug on the mine originally because this mine is already a problem, it was leaking a decade ago and it is still leaking today, just slightly slower than it did when the breach occurred.What to do about these streams is a long-standing problem in this region; press reports show that there has been debate about how to find money to deal with the waste from these mines for years, with only small projects undertaken. The water mostly just drains downstream and is diluted on a normal day.As a consequence of the spill, the EPA has halted mine reclamation activities in this area. The real worry though should not be that another spill like this one will happen…it’s happening right now just at a slow enough pace that people don’t regularly notice outside of the community. The real worry is that because of this spill, the pace of reclaiming and stabilizing these mines will slow down or stop, making the mine drainage go back to the state it was before the spill; present, but few people paying attention.-JBBImage credit: USGShttp://pubs.usgs.gov/of/2005/1064/References:http://pubs.usgs.gov/of/2007/1048/Read this post for a similar take on the chemistry: http://bit.ly/1TWPt1zhttp://www.fws.gov/southwest/sjrip/pdf/DOC_waterqualityreviewvol1.pdfActive San Juan River monitoring: http://bit.ly/1K6YMuYhttp://pubs.usgs.gov/wri/wri024230/pdf/WRIR02-4230.pdfhttp://www.durangogov.org/DocumentCenter/View/55 (big pdf)http://www.popsci.com/secret-history-epas-animas-river-spillEPA reports: http://1.usa.gov/1E6tlQs, http://1.usa.gov/1Lk2q3thttp://www.silvertonstandard.com/news.php?id=378http://bit.ly/1PmToDwhttp://bit.ly/1LlArDxhttp://bit.ly/1NFL41j -- source link

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