June 2012 - Atlantic Richfield hosted their annual public meeting in June, 2012 to present information to the community related to Warm Springs Ponds (WSPs). Presentations at the meeting were mainly related to water quality – other topics discussed included community education opportunities, recreational and wildlife values of the WSPs, and an evaluation of new modeling tools and treatment alternatives to ensure the ability to meet water quality standards after treatment through the ponds.
The Warm Springs Ponds were primarily created to keep contamination from Silver Bow Creek from entering the Clark Fork River. They were first built in 1911 with major improvements in the 1950s and again in the early 1990s. They have functioned well over the years in terms of metal retention with copper a major metal of concern. Copper is one of the most toxic metals to aquatic organisms and ecosystems and is of great risk to trout populations.
One noteworthy topic in the water quality update presentations are exceedances of the chronic water quality standard for copper at the Warm Springs Ponds outlet from June through September of 2011. This resulted in 11 violations of discharge water quality standards, as measured in required biweekly water quality monitoring. Prior to 2011, copper concentrations have been below water quality standards since 2007, with the exception of one exceedance in June 2008 and one exceedance in June 2010. Elevated copper levels observed in the summer of 2011 were higher than the chronic water quality standard of 0.03 mg/L, but did not exceed the acute standard of 0.05 mg/L.
Atlantic Richfield attributed copper exceedances from 2011 to above average flow conditions that resulted in a decrease in the retention time required for adequate treatment through the Warm Springs Ponds, and short circuiting of the system because of higher flow velocities. Reagent capacity (lime addition) was not believed to be a contributing factor, since target pH levels were achieved during the period of elevated copper effluent concentrations.
Impacts to the downstream benthic macroinvertebrate and fishery communities have not been evaluated at this time. The next biological monitoring event for the Warm Springs Ponds is scheduled for 2013. CFRTAC representatives made a recommendation to Atlantic Richfield after the meeting that they consider development of criteria related to measured water quality conditions and bio-assessment criteria that would trigger more frequent biological monitoring to ensure maintenance of unimpaired biological integrity of the downstream benthic macroinvertebrate and fisheries populations in the WSPs.
Ammonia discharge from the ponds has been of concern in recent years. However, recently ammonia discharge has improved. One of the factors involved in this improvement may be the use of solar bees on the ponds, which provide for better aeration and mixing of the water of the ponds.
Uncertainty surrounds the ultimate fate of the Warm Springs Ponds and Wildlife Management Area that covers about 4100 acres at the headwaters of the Clark Fork River. One central question is whether the ponds will remain intact (wet closure) or be drained and filled in with dirt (dry closure). Although it's early in the process, agencies disagree whether wet closure or dry closure is a better solution. Also unknown is how long they'll be needed. After the risk of mining contamination from Silver Bow Creek is reduced it is unknown how long the ponds will be needed to provide safety to the water entering the Clark Fork River with estimates ranging from five to 40 years or more. The Warm Springs Ponds continue to be an excellent source of outdoor recreation including fishing, hiking, hunting and bird watching as they provide habitat for a wide range of fish, birds and other wildlife.