Granite County Lake Quality
Montana, 1 lakes, average grade A (Excellent)
Only 1 lakes in Granite County carry an active grade. The county-level summary is therefore representative of those specific lakes, not necessarily of every water body in the county. The county's average grade is A — among the cleanest in {{stateName}}. 1 lakes pull an A on their own, and almost none fall into the D or F brackets.
The county's lakes lean shallow, which makes the grades sensitive to wind, sediment-resuspension, and any nutrient inputs from the watershed. The cleanest lake on the books is Nla Lake (A); the most-stressed is Nla Lake (A).
Quick Answers for Granite County
Planning a trip? Check special fishing regulations for Nla Lake — or check the official Montana fishing regulations.
All Lakes in Granite County
| Rank | Lake | Grade | Clarity | Phosphorus |
|---|---|---|---|---|
| 1 | Nla Lake | A | 28.4 ft | 6.4 µg/L |
Other Counties in Montana
See how Granite County stacks up in the national county water-quality rankings, or browse the full directory of graded lakes across all 34 states.
Where to stay near Granite County
Top-rated places to stay near Granite County
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a trip to Granite County?
Get lake water-quality report cards plus the best cabin & lodging deals near Granite County — straight to your inbox. No spam, unsubscribe anytime.
Source: EPA National Aquatic Resource Surveys, 2026.