Boulder Valley Frequency

In the shadow of the mine: Life near Colorado’s largest Superfund site

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0:00 | 17:25


July 10, 2026

Colorado's largest Superfund site by area stretches 400 square miles across Gilpin and Clear Creek counties, just north of Boulder County. The site has been in remediation for nearly five decades, and a new scope of remediation is assessing the health risk of lead left behind by historic mining to residents.

At Gilpin County's recent annual health fair, public health workers were testing residents' blood for lead. On today's episode, we sat down with Gilpin's Public Health director Alisa Witt to find out the risks this poses to county residents. 

Check out a map of Colorado's Superfund sites here
Did you know? Boulder County is home to 3 Superfund sites

Contact Gilpin County Public Health at 303-582-5803 to schedule free blood lead testing, or for more information on soil and well water testing.

More on Superfund budget + accelerated cleanups under the Trump administration: sciencefriday.com/articles/epa-accelerates-superfund-site-cleanup/



SPEAKER_02

B E H C the Frequency. Good morning. Happy Friday, Boulder Valley Frequency Listeners. My name is Kelly. I'm the audio producer on the show, covering for Shay, as I like to do on Fridays. Today, we're taking you to Gilpin County. It's just outside our normal coverage area. But just like we traveled to Hudson to cover an ICE detention center, we're also hopping our southern border for news about the decades-long impacts mining and heavy industry can have. Did you know of Colorado's 20 active Superfund sites, three are in and around Boulder County. Rocky Flats is perhaps the most well-known, but there's also the Marshall Landfill and Captain Jack Mill in Ward. The Trump administration's aggressive pursuit of industry deregulation and budget cuts to the Environmental Protection Agency endanger the cleanup of Superfund sites and potentially open up new areas of the country to mining. If rules are loosened, the environmental damage and impacts to human health could last for decades. This is not theoretical. Earlier this year, we reported on the potential reopening of the cross mine in Netherland. And while a bevy of state and local regulations are in place to protect local watersheds, there's no guarantee those would stand up to challenges under this federal regime. The EPA's Superfund budget was cut by nearly $250 million this fiscal year. But the Trump administration has accelerated cleanup of existing sites using $3.5 billion allocated under President Biden's bipartisan infrastructure law. There's no action item for today's story. Let's just listen and learn. Here is the Mountaineer's Tyler Hickman with the full scoop.

SPEAKER_03

Here's a pop quiz for you. Where is Colorado's largest Superfund site? For Gilpin County residents, it's just up the road. The Central City Clear Creek Superfund site stretches 400 square miles across Clear Creek and Gilpin counties, from the Continental Divide to Golden. Historic mining and acid mine drainage has exposed the public and environment to heavy metals, creating one of the most expansive, hazardous waste sites in the country. I'm Tyler Hickman. The EPA designated this area as a Superfund site in 1983 and has been remediating it ever since. In 2022, they established Operable Unit 5, a new scope of remediation, due to high levels of lead and arsenic found in mine waste piles on residential properties. Gilpin County is now offering blood-lead testing to its residents, while the community waits on the EPA and Colorado Department of Public Health and Environment to finish its human health impact study. Those results are expected in the coming months. For today's feature segment, we dig into the risks this mine waste poses to Gilpin's residents and what living with a superfund site in your backyard looks like.

SPEAKER_00

Oh and which arm? Uh left hand. I'm going to shake it up a little bit and get the blood flowing.

SPEAKER_03

The Mountaineer's Mindy Leary was on the scene to check out booths inside the community center, dedicated to physical and mental health, wildfire mitigation, and recovery resources. But one stuck out.

SPEAKER_00

Okay, so this figure, okay?

SPEAKER_03

A county-run kiosk was offering free blood-led testing for children and pregnant women, in large part due to the county's proximity to Colorado's most expansive Superfund site. We decided to catch up with the county to figure out the risks this poses to Gilpin residents.

SPEAKER_00

My name is Elisa Witt, and I'm the director of public health for Gilpin County. We haven't really done very much testing. We've been, we've had the capability to do that over the last couple of years. Blood-lead testing is much more important for children under the age of seven and women who are pregnant or thinking about becoming pregnant. Not that lead in blood isn't a problem for adults, but for most adults, it's not a problem. So really our target audience who we've been reaching out to and trying to get more testing done is for children, parents to bring their kids in to get tested. And like I said, women who are pregnant or thinking about becoming pregnant. In terms of the lead testing, I think because of the Superfund site, we do want to encourage people who are at risk. Other people that could be at risk is if they're on a private well and they haven't had their well water tested for metals. We do well water testing here at Gilpin County Public Health, but we're not able to test for metals. We can just test for bacteria and nitrates, and we do that on a regular basis. But a lot of residents who live on who have well water, which is, you know, the majority of Gilpin County and parts of Clear Creek County, don't realize that they're responsible for the quality of their drinking water. The state does not regulate private wells. They just recommend that people get their water tested annually. And unfortunately, most people don't.

SPEAKER_03

So I wanted to take a step back here just to get into the Superfund site. So I know that reclamation has been happening there for the better part of the last four or five decades. But the latest established operable unit concerns lead and arsenic in soil specifically. How great is the risk to folks that could be living near some of these sites or or have exposure to lead that is existing in the soil?

SPEAKER_00

Well, the human health impact study, which is part of the EPA's Superfund site, the current operating unit, that is about to be released. So I don't have my hands on the human health impact study yet. What's important to know is lead dust, which can is in mining tailings. So a lot of people back in the day build homes on top of old mines because the trees were already clear. It was nice flat land. And there was this nice light-colored kind of beige yellowish dust piles everywhere. Those are mining tailings, and that is what the EPA is concerned about. They did reach out to property owners, all property owners within the Superfund site, and it is the Clear Creek Gilpin Superfund site, and there is a map online available so you can see if your property is within the Superfund site area. Just because the mining tailings are sitting there doesn't mean it's all bioavailable. So what the researches have found is that from sunlight and many, many years of being exposed to the elements, it doesn't necessarily mean that those are all that heavy metal is actually could possibly be uptaken into your body and be bioavailable. So it's very important to, you know, not make any assumptions, get the answers from the researchers. They do know what they're doing. We're just right now waiting, should be within the next month or two, to get that human health impact study.

SPEAKER_03

The timeline was the investigation for human health impacts was going to be finished in 2025. So I figured we'd be coming up on something. Was this delayed at all? Is it later than you had expected?

SPEAKER_00

Yeah, it definitely was delayed. And that's also because new research came out recently that actually lowered the threshold for lead. I'm not sure about arsenic, but that they did come out with a lower threshold, especially for again, the thresholds really for children under the age of seven, pregnant women and women who want to become pregnant. And so right in the middle of them, you know, working on that human health impact study, they got some new data that caused them to have to re-look at that. The good news is mitigation is definitely possible. And so sometimes what they'll do is they'll come and cap the ground and cover up those tailings. Sometimes they'll remove as much as they can and then they'll retest the soil. So I would say, you know, the risk right now, in my opinion, is largely from the dust being tracked into your home by pets or on the bottoms of your shoes. And then if you had an infant that was crawling, they'd be contacting that dust. And I know that's hard. I'm I'm a pet owner myself. I have two big dogs, and like the thought of washing their paws off before every time they come in the house just doesn't seem tenable. But that's the recommendation. If you have that light-colored dirt and potential mining tailings on your property, you should try not to be letting that lead dust into your house as much as possible.

SPEAKER_03

And do folks who did have lead testing done at their homes by the the, whether it's the state or the the EPA, do they have those results as of now? Okay. Yes.

SPEAKER_00

Yep. They do. And then the ones that are eligible for mitigation have been contacted and they're working down, they're going to start with those that had the highest levels and offer them solutions to mitigate their properties.

SPEAKER_03

The risk is both in the dust being tracked into your home, the lead existing in the dust, but the risk could also be uh groundwater leaching into wells that is also a risk.

SPEAKER_00

Yeah. Yeah. We definitely, I think it's important for anybody living in Gilpin County, Clear Creek Counties, where there have been historic mining, but also just the nature of our soils. Like we have heavy metals naturally, not just from mining, lead, arsenic, cadmium. So there are labs that do specific packages for this environment where they're going to test for the metals that are most likely to be here in Colorado. And you'd want to say that to a water testing company, you know, like I want to test for the specific metals that would be in the Colorado geology.

SPEAKER_03

Kind of a broader question here because I'm I'm I'm just interested in what living in a super fund site is like. And this is far and away the largest super fund site in Colorado. It's 400 square miles. When you're living in a super fund site like this, does it come as a surprise when you find something out, you know, a decade after remediation has begun on one aspect that they need to be, they need to start remediating another aspect of the site?

SPEAKER_00

Yeah, well, I mean, it I think that the way that the researchers went about the Superfund site, and yes, it has been taking decades, is they looked at, they always look at, you know, what's the highest risk, and let's address that first. And that is why they put in the water treatment plant in Clear Creek, which was part of the previous operable unit, because that was a much bigger risk to the environment and human health to have these heavy metals in the watershed. And they're they're difficult to filter out also for municipal and county water treatment plants. So that is why they started there, I'm sure, is because that was a much bigger risk. Keep in mind, you know, these mining tailings, yes, they're a risk, but you literally have to get into a position where you're ingesting that dust. And that can happen. I mean, we we have dirt roads here in Gilpin County. We have a lot of road dust that comes into our homes. I personally don't live in the Superfund site, but I would say that, you know, if you're aware, and it's easy to see, it's easy to see the color of the tailings. You know, they're definitely different. They're not dark, dark color, they're lighter colored. They're they're unusual colors of light brown, tan. They're pretty obvious once you know what to look for. The idea is don't let your kids play in on that area. Don't let your dogs and cats and animals walk through there. Don't track it into the house. It's not, you know, it's not impossible to avoid if you know what to look for. And we'll see. I mean, I've been waiting a while for this human health impact study. We'll see what the researchers say, you know, about how much of the stuff that's been sitting in the sunlight for 10, 20, 30, 50 years is actually potentially harmful and how how much isn't. I'm an optimist. I'm I'm thinking, you know, that it's not that if there was a chance that it was, you know, seriously immediately dangerous, they would have addressed it sooner. The first step was to get those samples, and that's what they've run. Yeah.

SPEAKER_03

I I know you just kind of started the blood-lead testing, but has anyone um tested with higher levels of of blood above that threshold? Do you know that?

SPEAKER_00

Yeah, well, we haven't tested very many people so far, but nobody that we've tested came out as in a dangerous lead level. Even a couple of people who have been exposed to it occupationally did come out fine. We tested them at the screening. But we haven't tested very many children, and that's really what we'd like to do. Um, it is just a finger stick. It's it's a little pinch, it's not real painful. With mom or dad's permission, if they bring a child in, you know, we'll give them a prize, we'll give them stickers, we'll be super nice to them. But, you know, you can you can get you can request that from your pediatrician's office, and you should if you live in the Superfund site, or you can come in here and we can do it. It's a five-minute test. I'm a little bit frustrated that that, you know, we've sent postcards out twice now to all the households, and we haven't had any parents want to have their kids tested. Now, maybe they're getting them tested at the pediatrician's office, but I think that's super important for anybody living in the Superfund site. If you have a child seven years of age or younger, or you're pregnant, or thinking about becoming pregnant, we really suggest you give us a call. We'd be happy to test you for free.

SPEAKER_03

Before we jump off here, is there anything else that you wanted to say? Something important, closing words about getting your blood tested.

SPEAKER_00

Just like I said, you know, the problem with lead in children's blood is it can cause permanent disability, mental cognitive lessening of IQ, cognitive problems. So it's something, you know, that's not reversible if the damage is already done. There's definitely ways to lower that blood lead and things that you can do to mitigate it, but neurologically, the whole point is prevention. That's why we're offering this. Give us a call. Um, we're here Monday through Thursday, 7:30 to 5.30. You can we can make an appointment that's convenient for you. If you live in Clear Creek, you can call Clear Creek Public Health and they will do that. Also, if you're living within the Superfund site and you either didn't get the email or the letter in the mail from the Superfund people, or you've changed your mind and now you want to get your property tested, um, you can also call our office. Our number is 303-582-5803, and we can connect you with those researchers, and they will, they said they will still come out at request and test properties within the Superfund site. So that's still an option for you. And it's a good idea because again, they will mitigate that at no cost to you.

SPEAKER_03

So thanks, Elisa. Find more information about soil and water testing at Gilpin County's website. If you want to learn more about the Central City Clear Creek Superfund site, the EPA has some great resources online, including an interactive map where you can see the boundaries of all the Superfund sites in the state. We'll link to it in the show notes. That's all for today. I'm Tyler Hickman. Thanks for listening. We'll see you next week.

SPEAKER_01

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