Is Rosemount's Water Safe? What the Experts Said About Well #8 and Gross Alpha
Is Rosemount's Water Safe? What the Experts Said About Well #8 and Gross Alpha
TLDR
- Rosemount's Well #8 went just over the federal limit for gross alpha radiation in early 2026 — a yearly average of 16 versus a limit of 15.
- Gross alpha is natural radiation from radium in the deep rock, not pollution from any company.
- Experts called it a "chronic" risk, meaning harm only comes from decades of drinking water over the limit — so the city and state say your water is safe to drink now.
If you've been worried about your tap water, the June 18 meeting at the Steeple Center was built for you. The headline issue is one we've followed for months: gross alpha radiation in Rosemount's Well #8. Here's the plain-English version of what the experts said.
What Gross Alpha Actually Is
A compliance engineer from the Minnesota Department of Health did the explaining. "Gross" just means total, and alpha is a type of radiation. So gross alpha is the total amount of alpha radiation in a sample of water. It's measured in tiny units called picocuries per liter.
Where does it come from? Nature. Radium and similar minerals sit in the deep aquifer Rosemount pumps from, and they naturally give off this radiation. It is not from the data center, not from a spill, and not from anything anyone dumped. The same engineer was clear about that.
Why the Number Went Up
Here's the part that surprised a lot of people. The rules around gross alpha haven't changed since 2004. What changed was the groundwater itself.
The health department said gross alpha levels rose across all of southern and central Minnesota last year as underground conditions shifted. Rosemount is far from the only city dealing with a violation. So this wasn't the city getting sloppy — it was the water under everyone's feet changing.
Rosemount's yearly average came out to 16, just above the limit of 15. That tracks with the climbing readings residents have raised at past city council meetings.
So Is It Safe to Drink?
This is the question everyone wanted answered, and the experts didn't dodge it. Gross alpha is what they call a "chronic" contaminant. That means there's no expected health risk unless you drink water over the limit for decades. It's nothing like a contaminant that can make you sick today.
Because of that, the state doesn't judge it on a single bad test. It uses a running yearly average — a full year of data — to decide if a city is over the line. Rosemount crossed that line by a single point, and the city and state both say the water is safe to drink right now.
That's also why the city has kept Well #8 toward the bottom of its rotation, so less of that water reaches your tap while a long-term fix gets sorted out. If you've got little ones at home, it's also worth knowing the city has a free filter pitcher program tied to a separate manganese issue.
The Bottom Line
Gross alpha is a real issue Rosemount has to fix, but it's a slow-moving one, not an emergency. The city has already notified residents, filed a plan with the state, and is moving toward a permanent solution.
The smartest move for residents is to stay informed. The city now posts a water update every quarter, and it's worth a bookmark so you can watch the Well #8 number over time instead of guessing.
FAQ
Do I need to buy bottled water? The city and the Department of Health say no. The water is considered safe to drink.
Is gross alpha from the data center? No. It's natural radiation from radium in the deep rock, and it predates any data center talk.
How far over the limit is Rosemount? The yearly average was 16 against a limit of 15 — just over, not far over.
Why can't they just fix it overnight? The lab testing alone is slow chemistry that follows federal methods, and the real fix means building or rerouting infrastructure.
Where can I see the actual numbers? The city's water quality page posts the reports and quarterly gross alpha updates.
Note: water quality can be a stressful topic, especially for families. If a specific health worry is keeping you up, the Minnesota Department of Health and your doctor are the right people to ask.
