Silver Bow Creek: A Restoration Story

A pdf of this post is available here: Silver Bow Creek pdf

Introduction
In the process of hard rock mining, the desired ore is extracted from its surrounding rock matrix by crushing the composite and treating it with a variety of chemicals. This treatment causes the desired metal to precipitate out of solution and allows for collection. The remaining, left-over material is called mine tailings. Mine tailings often contain a slurry of different chemicals such as pyrite (FeS2) and Iron(II)sulfide (FeS) (Benner et al. 1995). These sulfide waste products are extremely harmful to many organisms, including humans, and proper waste management is of the utmost concern. When sulfide mine tailings are exposed to water, metals such as iron and manganese will precipitate out of solution and become oxidized. This oxidation process causes a subsequent decrease in the water’s pH. Therefore, mine tailings cause stream water to become acidic and contain aqueous and precipitated metals that are harmful to organisms (Benner et al. 1995).
Silver Bow Creek

The Clark Fork River basin is home to a diverse assemblage of vertebrate and invertebrate animal species including nongame species such as songbirds, small mammals, and the especially sensitive aquatic invertebrates of the orders Ephemeroptera, Plecoptera, and Trichoptera. A number of economically important, native game species including elk (Cervus canadensis), moose (Alces americanus), white-tailed (Odoceolius virginianus) and mule deer (Odoceolius hemionus), pronghorn (Antilocapra americana), bull trout (Salvelinus confluentus), and the iconic westslope cutthroat trout (Oncorhynchus clarki lewisi) are also endemic to the region.

Mine Waste Disposal at Silver Bow Creek
Silver Bow Creek is a 26-mile long, small order tributary of the Clark Fork River of western Montana. With its origin in the historical mining town of Butte, Silver Bow Creek has a long history of misuse and abuse. Starting in the late 1800’s and continuing through much of the 20th century, Silver Bow County’s major economic activity revolved around mining activities, especially for copper (Dickson 2012).
In Silver Bow County, much of the mine waste throughout the primary operation period of the mines was simply dumped outside of the urban areas of Butte, Rocker, and Walkerville. Unfortunately, one of the primary areas where tailings were dumped was along and within Silver Bow Creek. In addition to dumping along the creek, a number of flood events caused the tailings to become distributed throughout the floodplain of the Silver Bow drainage (Mullen and Chavez 2012). The tailings also infiltrated the local groundwater, allowing the heavy metal waste to be distributed to a much wider extent, especially within the flow path of the creek (Benner et al. 1995).
After significant mining activity took hold in Silver Bow County and mine tailings started to be improperly disposed of, local populations of the aforementioned animal species endemic to the region declined significantly, especially those of the aquatic invertebrates and trout (Morey et al. 2002). As such, safe use of the water for human consumption and angling recreation were compromised. Additionally, riparian plant communities collapsed and Silver Bow Creek become virtually devoid of vegetation.

ARCO Lawsuit and Fallout
In 1983, the state of Montana filed suit against the Atlantic Richfield Company (ARCO) alleging that improper mine waste disposal had compromised the ecological integrity of Silver Bow Creek. In 1998, the parties entered into a settlement worth $215 million and parts of the Silver Bow Creek watershed were designated as Superfund sites (Confluence 2005). Superfund is a program operated by the U.S. Environmental Protection Agency (EPA) that designates areas where water has become unsafe for human use and allocates funds for site remediation. Since 1999, the state of Montana has been distributing ARCO and EPA funds to public and private entities throughout the Silver Bow Creek basin for restoration and monitoring activities. This generated $85 million for the local economy alone (Confluence 2005).

Restoration Activities
While restoration activities funded by the state have varied widely, the vast majority of funds in Silver Bow Creek have been spent on removal of contaminated soils in the creek and floodplain and channel reconstruction and revegetation (Mullen and Chavez 2012). To date, 80% of Silver Bow Creek has been restored and 4.1 million cubic yards of an estimated 4.5 million cubic yards of mine waste has been removed. This equates to 1,310 acres of the 1,400 acres initially contaminated (Mullen and Chavez 2012). Excavation of contaminated soils also allowed for the creation of a number of wetlands that provide habitat for waterfowl, fishes, amphibians and other species.
In addition to waste removal, channel reconstruction and riparian & instream habitat creation has been prioritized. Large portions of the creek have been manipulated to create more meanders, pool habitats, and varying channel widths. Like many large scale restoration projects, the Silver Bow restoration was divided into a number of zones where needs were assessed and different projects implemented (Mullen and Chavez 2012). The final zone of the initially scheduled areas for restoration was completed in 2013.

Response and Future Directions
Westslope Cutthroat Trout caught in Silver Bow Creek
While drinking water standards have not yet been met for Silver Bow Creek, water quality has vastly improved and metal concentrations are much lower (Mullen and Chavez 2012). Riparian vegetation has returned to large portions of the steam and several flood events have not caused undue changes to channel structure (Confluence 2005). Perhaps the most significant sign of improvement is that beginning in 2006, fish returned to Silver Bow Creek after nearly 100 years of absence. Populations of suckers, sculpins, and the iconic westslope cutthroat trout have become naturally reproducing in the drainage and the Silver Bow Creek trout fishery is gaining renown across the state (Dickson 2012). Additionally, increases in bald eagle, moose, beaver, muskrat, mink, insect, and sandhill crane populations have been observed (Mullen and Chavez 2012).

            While some areas of Silver Bow Creek are still being restored, this project is becoming known as one of the most successful mine waste cleanup projects in the country. Continued success on this small headwater of the Columbia will undoubtedly provide increases benefits to the people, plants, and animals that call this area home.

References

Benner, S.G., et al. (1995) Metal Behavior During Surface-Groundwater Interaction, Silver Bow Creek, Montana. Environmental Science and Technology 29, 1789-1795.

Confluence Consulting, Inc. (2005) Silver Bow Creek Watershed Restoration Plan. Report to Montana Natural Resource Damage Program.

Dickson, T. (2012) Silver Bow begins bouncing back. Montana Outdoors. September 2012, 56-57.

Morey, E.R., et al. (2002) Estimated recreational trout fishing damages in Montana’s Clark Fork River basin: summary of a natural resource damage assessment. Journal of Environmental Management 66, 159-170

Mullen, G. and J. Chavez (2012) Remediation and Restoration of Silver Bow Creek. Montana Department of Justice report.

Scaling in Fisheries Management, Part Two: Conceptual Models

In the last post, I discussed scaling in fisheries habitat science. I finished by talking about limiting factors, or the variable that is not allowing a fish population to grow. Often, determining what is actually limiting a population's growth is incredibly difficult and can be different for fishes of different ages, species, and locations. In that case, how do fisheries biologists determine what actions to take to try to help struggling populations and grow their populations? Well, we start with conceptual models. Unlike some models that provide specific, quantitative predictions and are often used at the expense of real, on-the-ground data collection, conceptual models just provide a hypothesis. Conceptual models are basically a set of qualitative ideas about how fish populations respond to different variables. For example, a simple qualitative model might predict that land uses such as grazing, farming, and urbanization will impact water quality metrics such as sediment and temperature which will in turn affect the parameters of population growth (see Fig. 1). It does not make specific predictions about how much sediment input will be changed by grazing or how a food supply will be impacted. It simply suggests there might be an impact.


Figure 1. Conceptual Model of land uses on population growth

Once a conceptual model like this is created (and it can simply be an idea not a drawn out diagram),
biologists can decide what parameters of each section are having the greatest impact on the next section (i.e. that grazing is causing increases in temperature that is causing higher juvenile mortality). This provides a starting point for a biologist to make an alteration in a system and watch the response of the population. If the population does not respond as predicted, the biologist will need to rethink the conceptual model or determine if a different parameter is responsible. 

Conceptual models can be especially useful at large scales where climate, hydrology, and geology all impact streams in different ways and have impacts on large and small scale parameters. 

Scaling in Fisheries Management, Part One: The Limiting Factor

This is part one of a four part series on scaling in fisheries biology. 


Humans are often biased by what they can see with they're own two eyes. People are a lot more like Doubting Thomas than most would like to admit. Accepting that the Earth was a sphere was difficult for most people because we only perceive the Earth as being flat. But, in eventuality, the true nature of a problem tends to come out. In fisheries, we have traditionally focused on fish that live in a relatively small area (a reach) and applied what we learned there to an entire population. For example, biologists might snorkel a small section of a creek and observe what type of habitat cutthroat trout are using. If,  for example, they find that 90% of the trout are hiding in woody debris even though the creek habitat is only 10% woody debris, they might assume that cutthroats require woody debris. While this makes intuitive sense, it is often the case that adding woody debris to a stream doesn't end up increasing the trout population. Well, what's going on here? If the fish aren't responding to more woody debris, what is actually happening. Evidently, we haven't found the variable that is limiting the cutthroat trout population. In other words, something other than woody debris is not allowing the population to grow any larger. Whatever is actually limiting the population is called the limiting factor. Now determining what the limiting factor for a population is can actually be extremely difficult. There are tons of possible variables that might be responsible. How do we know if it is a lack of spawning gravels, or woody debris, or increasing temperatures, or sediment input, or fertilizer run-off, etc., etc.? Well...we usually don't. There is often just no possible way to determine what of a great number of interacting and interwoven variables is limiting. That is where conceptual models come in...yes, models. The term I usually use as a dirty word. More on that in the next post.

Simplicity in Fishing and Fisheries: The Tenkara Way

Tenkara. The ancient form of fly fishing developed in the mountain streams of Japan. What makes tenkara different from American/European fly fishing? Well, mainly the lack of a reel. Instead, a woven fly line is attached to the end of a long, telescoping rod at its terminal end. At the end of the fly line, a single piece of clear monofilament is attached and a fly tied on at the end. Perhaps most puzzling to western anglers is that true tenkara masters only use a single fly pattern! There's good reason for this however. In our modern "match-the-hatch" fishing craze, we often obsess about getting the fly to exactly match whatever it is that seems to be landing on the water. With tenkara, the focus moves away from exact imitation of a physical appearance to one on the action of the fly in the water.  In other words, tenkara anglers are focusing on their fishing skills and not compensating for inexperience with a three dollar piece of foam. In fact, tenkara fishing is so simple in its design, that a person can get out and fishing with nothing but a rod, a fly, monofilament, and a line. No need for overstuffed vests or bulky chest packs. I like to grab my setup, which I can carry by hand, and take the bus to the local river. It's beauty is in its simplicity.
First trout caught on a tenkara rod.
https://www.instagram.com/niall_clancy/


In modern ecological science, we have become obsessed with creating complex mathematical models and statistics that allow us to find significance where there is none. Now, don't get me wrong, there is a place for models and fancy statistical methods, but I believe they are overused at the expense of important naturalistic observation. I propose that we ecologists need to take a lesson from Tenkara. The most efficient and most beautiful way to do things is often the simplest way. Let me provide a more concrete example. In modern salmonid management, vast resources are spent in an effort to predict exact recruitment numbers, fecundities, and food consumption in many systems. While valuable in many cases, little is known about a great many species that interact with these salmonids. Maybe if we knew some of the basic behaviours and movement patterns of the non-game species in these systems, we would have a better understanding of how to manage the salmonids as part of an entire community animals.

It is understandable that scientists want to be on the cutting edge of their field. Doing things that could be done with the technology of fifty or even a hundred years ago does not wow other academics. But if we want to understand how to manage fisheries and not just fish, we need to understand the basic, observable characteristics of all species in a community, not just have very complex models of a single species. Maybe it's time to get back to the basics.




This post was sponsored by the Tenkara Rod Co. of Driggs, Idaho who generously provided me with a tenkara fishing outfit free of charge. If you would like to experience tenkara fishing for yourself, I highly recommend trying out the high quality products from the Tenkara Rod Co. However, all opinions in this essay are my own and do not necessarily reflect the views of the Tenkara Rod Co. or any individual other than myself.


The Iceland Study -- Global Change and Streams

video
National Science Foundation video about Dr. Wyatt Cross et al.'s study on climate change in Iceland streams. I was involved with this study last year helping to process invertebrate samples from the different streams.

Fisheries Management Databases

I recently read a paper as part of Dr. Andrea Litt's lab at Montana State that called for a new database where fisheries & wildlife scientists can deposit their reports on various management actions. This paper was published in 2004 and to my knowledge such a database still does not exist. While I lack the skills/time to create such a database, I've decided to compile a few links to different report collections relevant to Montana fisheries.

Montana Fish, Wildlife & Parks


Montana Department of Environmental Quality

Montana Natural Heritage Program