How Do Agencies Determine the Health of Silver Bow Creek?

Have you ever wondered how they determine how effective the Superfund remedy is? In previous episodes we talked about the health studies and how the agencies are trying to measure the effects on human health. But how about the environment. We have standards for the amount of metals in the creek or in the soil, but how do we know these levels are really protective of the environment? One way is to look at the health of the fish in the creek, as biologist Jason Lindstrom of Montana Fish Wildlife and Parks has done. Jason gave a presentation to the Butte Natural Resource Damage Counsel last Thursday on his findings.

He began his talk with an overview of the history of the creek, of the floods that washed mining waste from Butte down to the Bonner damn, and the devastation to the fishery. And he talked about the cleanup that began after the creek was listed as a Superfund site, and the long process to rebuild it.

JL: “1999, so that was, what, nineteen, almost twenty years ago, now that cleanup began on Silver Bow Creek and the last section was completed in 2015. There’s still a little bit of cleanup work happening in the flood plain, but the last of the main channel reconstruction was done in 2015. So that was a sixteen-year process, and it was very very very invasive. Unlike anything else in the state, to do that many miles of the channel, and to completely rebuild the whole thing.”

Jason went on the describe how they assess the health of the fishery, primarily through fish counts. FWP goes out twice a year to perform these studies, they electro-shock, and count and characterize the fish they find.

JL: “In 2002 is when FWP initiated sampling in Silver Bow Creek proper. And That’s just shortly after the remediation started, just downstream of Butte. At that time, we just sampled within Butte and in a section above Rocker, and the only thing they found in those sections were suckers and a handful of sculpin.”

Initially, they were just looking for any signs of life.

JL: “All the sampling that was done between 2002 and 2014 was all low effort presence/absence type sampling. We were just trying to see if fish were there or not, and it was really hard to get density estimates, like how many are there, because there really weren’t a lot of fish to deal with that.”

And post remediation, they started to see a real rebound in fish populations. Beyond a few sculpin and suckers, they started to see trout in numbers.

JL: “And in 2010 is the first time we see trout in every one of our sampling sections. So, they were really starting to spread out within the system.”

As the trout began to come back their attention shifted to specific species. Native game fish such as the Westslope Cutthroat became the focus.

JL: “So, management direction, our focus is on sustaining and enhancing a native Cutthroat fishery, and that jives really well with the original Silver Bow Creek watershed plan that was done a long time ago now, where ‘native species maintained and restored where practical’ was one of the main visions for Silver Bow Creek.”

A fish barrier was constructed on Silver Bow Creek in Durrant canyon in order to preserve the genetically pure Westslope Cutthroat found in the watershed. This barrier, which resembles a concrete waterfall, will not allow nonnatives like Rainbow and Brown trout to migrate upstream and crossbreed.

The tributaries of Silver Bow Creek are prime habitat for Cutthroat. Jason talked about the main tributaries and their contributions.

JL: “Basically three main tributaries drive the fishery in Silver Bow Creek. That’s German Gulch, which is the lowest one down, Browns Gulch, and Blacktail Creek. Basin Creek comes in here, but it’s not a significant enough producer of fish, mostly Brook trout in there and nowhere near close to the densities of these other streams. So, these are the three primary tributaries that drive the Silver Bow creek fishery. German Gulch is the big one, it’s the shortest drainage of all these three, has a lot of the water that’s coming into the creek and definitely a lot of the Cutthroat trout. It’d predominately Cutthroat in the German Gulch system and it’s pumping out a ton of them. It’s really what’s driving the Silver Bow fishery, from the Cutthroat perspective, based on everything that we’ve looked at for the last decade or so.”

And these tributaries are very important for the fishery, especially for the Cutthroat. They provide cool water and food throughout the summer, and these high elevation refuges are particularly well-suited habitat.

Most sections of Silver Bow have followed a similar pattern since remediation. Jason talked about a particular section near Ramsey, that is representative of the stream in general.

JL: “This section was completely fishless pre-remediation, it was remediated in 2005, and in 2006 right after it was remediated we had suckers and sculpin there, but no trout. By 2007 we were seeing trout, and as you can see, Cutthroat really started to come on. Right in here, 2012, 2013, we’re dipping and diving but we’re not really dealing with that many fish, a couple fish can make a big difference here. Ever since about 2010, it’s just kind of stagnant, and that’s what we’re seeing in most of our sections. Just kind of a stagnation of trout density. We saw this really cool response right after remediation came through but now we’re just kind of holding at these fairly low levels throughout the creek.”

So, the creek experienced a significant recovery after the initial remediation, but trout populations have plateaued since then. Jason spoke to the challenges to the fishery. Lack of habitat and water temperatures in the summer play a part, but metals are still a factor.

JL: “Butte storm water runoff, we know from a study we did back in 2008 with caged fish, that that was a problem then and it still seems to be a problem now, from what we understand. We know that when it rains, it really doesn’t even take that much of an event, and metals hit Silver Bow creek and Blacktail creek, and it kills fish. We have the data to show that from that 2008 study, which was a really small simple study, but it was very clear what was going on there.”

So, there you have it. The remediation of Silver Bow Creek has been effective in reestablishing a population of trout in the watershed. We have a unique area with genetically pure Westslope Cutthroat trout who will be isolated and allowed to flourish without competition and crossbreeding from nonnative species. The fishery still faces challenges, with habitat issues as well as remaining metals contamination, but for the most part remediation has been a success. If we can figure out how to deal with our storm water, they will be well on their way to a complete recovery.

I’m Dave Hutchins reporting for KBMF.