Podcast Summary: Short Wave

Episode: The world’s freshwater is getting saltier. Why?
Date: March 25, 2026
Host: Emily Kwong
Producer/Reporter: Burley McCoy
Guests: Hilary Dugan (Freshwater Scientist), Kyung Do “Do” Han (Groundwater Postdoc), Allison Madison (Saltwise Nonprofit), Brian Vogt (Contractor)

Overview

This Short Wave episode delves into the surprising and growing issue of freshwater sources—lakes, rivers, and groundwater—becoming saltier worldwide. Through a trip to Madison, Wisconsin, host Emily Kwong and producer Burley McCoy investigate how road salt and other human activities are altering the chemistry of water we depend on. They explore the environmental, ecological, and human health consequences, spotlight innovative solutions, and discuss the challenges of “desalting” our freshwater future—all in Short Wave’s trademark mix of clarity, curiosity, and humor.

Key Discussion Points & Insights

Why Is Freshwater Getting Saltier?

• Major Contributors:
  • Road Salt: Millions of tons used in snowy regions wash into lakes and rivers during winter.
    • “Here in the Midwest, we're, you know, putting millions of tons of road salt into the environment every winter.” – Hilary Dugan [01:16]
  • Other Causes: Runoff from fertilizers, mining activities, and seawater intrusion—especially when aquifers are over-pumped and ocean water seeps in [05:14].
  • Climate Change: As temperatures rise, more water evaporates, concentrating the existing salt [05:36].

Madison, Wisconsin: A Case Study

• Local Impact:
  • Madison’s lakes had little salt before road salt usage. Now, Lake Wingra is at over 100 mg/L, nearing tastes detectable to people [04:44].
  • Broader Scope: In 2017, half of hundreds of surveyed lakes in the northern US and Canada showed increasing salinity [04:50].
• Quote:
  • “Before road salt was introduced, the lakes around Madison had virtually no salt. Today…at over 100 milligrams per liter.” – Burley McCoy [04:29]

Environmental Impact

• Toxicity: Even minor salinity changes harm aquatic plants and animals; existing levels in Madison’s lakes are toxic for fish, snails, and zooplankton [05:54].
• Invasive Species: They often thrive in higher salinity, potentially displacing native species [06:17].
• Subtle Harm:
  • “Even if you're not dying, you still might be stressed by that high salinity…you're not gonna necessarily die, but…you're not gonna feel good, and it might be affecting other parts of your health.” – Hilary Dugan [06:35]

Salinity and Human Health

• Drinking Water: Elevated salt is appearing in some municipal wells, not just lakes [07:02].
  • “Yikes. Okay, one well… Well 14 passed 120 milligrams per liter in 2014…not bad for you, unless you're on a low sodium diet.” – Emily Kwong & Burley McCoy [07:32]
  • “People have documented rising chloride levels in wells across the U.S.…in rural places and urban places.” – Burley McCoy [07:37]
• Chloride Persistence:
  • “Chloride is a persistent chemical, persistent substance that doesn't go away easily…We're still getting the legacy of salt used from 1970s and 1980s.” – Kyung Do Han [08:56]

Challenges of Removal

• Desalination is Costly:
  • “To get the salt out of the water, you gotta boil it…or use reverse osmosis. And both are really expensive and require a lot of energy.” – Kyung Do Han [08:14]

Societal Impacts

• Some communities must buy bottled water because groundwater is too salty, even impacting farmers (like forcing a family to sell dairy cows) [09:16].

Solutions & Innovation

Saltwise & Reducing Road Salt

• Nonprofit Advocacy:
  • Saltwise leads education and training to curb salt use—removing excess, calibrating equipment, measuring pavement temperature, and advocating for alternatives [09:42].
  • “I think of it as kind of being a cheerleader for using less salt.” – Allison Madison [09:56]

Brining the Roads

• Liquid Brine Application: Spraying brine before storms keeps salt in place and prevents snow from bonding to pavement [10:24].
• Quote:
  • “If we can prevent the bond from forming between the snow and the pavement, it takes a lot less salt on the back end.” – Allison Madison [10:53]

Grassroots Engineering

• Contractor DIY:
  • Brian Vogt built his own brine truck and homemade brine maker; he now uses substantially less salt for snow removal [11:28].
  • “Once you figure this out, the liquid, you can get it done with way less salt.” – Brian Vogt [12:21]
  • “The properties that I do and I service don't look like those properties that have…you're tripping on salt.” – Brian Vogt [12:11]

Is It Enough?

• Major Reductions:
  • Madison has dropped salt use by about 40% [12:44].
• Tough Tradeoffs:
  • “If I was going to tell people we need to stop using salt, I would be laughed out of the room…But from an environmental perspective, yes, we should stop using salt today.” – Allison Madison [12:51]

Broader Reflections

• Lasting takeaway: Solutions are both simple (stop adding salt) and hard (changing long-standing habits and expectations). But persistent, community-level efforts can make a significant impact [13:11].

Notable Quotes & Memorable Moments

• “We're now talking 70 plus years of road salt use. And what we've seen in the lakes is the salinity kind of steadily increasing year after year as more and more salt is put down.”
  – Hilary Dugan [01:32]

• “Chloride is a persistent chemical…those are still affecting our lives, present day.”
  – Kyung Do Han [08:56]

• “The obvious way to slow or stop water from getting saltier is to use less salt.”
  – Burley McCoy [09:38]

• “Once you figure this out, the liquid, you can get it done with way less salt.”
  – Brian Vogt [12:21]

• “If I was going to tell people we need to stop using salt, I would be laughed out of the room. Right? But from an environmental perspective, yes, we should stop using salt today.”
  – Allison Madison [12:51]

Timeline & Timestamps

• [00:31] – Introduction to freshwater salinization as an emerging global threat
• [01:16] – Hilary Dugan explains decades of road salt use and environmental build-up
• [04:44] – How salinity in Madison’s lakes has risen since road salt was introduced
• [05:07]–[05:46] – Other sources: run-off, mining, seawater intrusion, climate change
• [05:54]–[06:35] – Ecological impacts and example of species stress/death
• [07:02]–[08:02] – Salinity entering human drinking water and health guidelines
• [08:05]–[08:56] – Difficulty of filtering/removing salt; historical persistence
• [09:38]–[10:53] – Advocacy for less salt, industry education, and technological solutions (brine)
• [11:02]–[12:21] – Grassroots innovation with brine trucks and their effectiveness
• [12:44]–[13:11] – Evaluating if these efforts are enough; practical constraints

Takeaway

Freshwater salinization is a creeping yet under-appreciated environmental crisis, driven by common practices like road salting and exacerbated by climate change. While challenging to reverse, meaningful progress is possible through smart policies, technical innovations, and community engagement. The episode illustrates how environmental solutions, though not easy, can succeed piece by piece—and that everyone, from scientists to snowplow drivers, has a role in protecting water’s delicate balance.