Tally Lake
Flathead County, MontanaView mapDirections
Montana DEQ publishes the water-quality measurements for Tally Lake. Here is what has been measured.
- Oligotrophic
Tally Lake in Flathead County, Montana has water-quality measurements published by Montana DEQ, shown here as reported. Water clarity: 15.2 ft visibility. Phosphorus: 4.7 µg/L. Chlorophyll-a (algae): 0.8 µg/L.
Tally Lake is a cold, clear oligotrophic lake in Flathead County, Montana. Overall water quality is declining over recent sampling years. Compared to the 43 other monitored lakes in Flathead County, Tally Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Montana DEQ, last sampled 2023-08-15. Methodology: how these readings are compared.
If you are planning to stay, you can search lake houses and cabins around Tally Lake on Vrbo, or look for a hotel room near the lake on Booking.com or Expedia.
What Tally Lake is good for
From access and monitoring records, not editorial picks.
- Clear water15.2 ft of visibility
- Camping1 public campground nearby
Swimming conditions
Readings onlyLow algae
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Tally Lake is safe to swim in today is a call for the Montana Department of Environmental Quality and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Tally Lake
These are the measurements Montana DEQ publishes for Tally Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Crystal clear, you can see 15.2 ft down. Phosphorus 4.7 µg/L. Chlorophyll-a 0.8 µg/L. TSI 31.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 15.2ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 4.7µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | 0.8µg/L | Good GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 31 | Oligotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Low nutrients, clear water. No reading is a swimming clearance.
Ask about Tally Lake
Answers come straight from the public measurements and survey records on this page.
Recreation & Access
Public campgrounds near Tally Lake
- Tally Lake Campground2.2 kmReserve
Nearest public campgrounds in the USGS National Map inventory, within about 3 miles. An empty list means USGS records no campground that close, which is not the same as camping being unavailable. Where the source gives an official reservation link, it is used; the cabin and hotel search does not cover campsites. More camping lakes
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Stays near Tally Lake
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Top-rated places to stay near Tally Lake
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Fishing Tally Lake
Water Quality Trend: Worsening
Based on 12 years of monitoring (2012–2023).
Water clarity
Worsening9 years
Phosphorus
Stable+0.04 µg/L/yr12 years
Chlorophyll-a
Worsening+0.09 µg/L/yr12 years
Nearby Lakes in Flathead County
Frequently asked questions about Tally Lake
Where is Tally Lake?
- Tally Lake is a lake in Flathead County, Montana. Its water-quality measurements are published by Montana DEQ and shown on this page as reported.
What is the water quality of Tally Lake?
- Tally Lake in Flathead County, Montana has water-quality measurements published by Montana DEQ, shown here as reported. Water clarity: 15.2 ft visibility. Phosphorus: 4.7 µg/L. Chlorophyll-a (algae): 0.8 µg/L.
Is Tally Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Are there campgrounds on Tally Lake?
- Tally Lake has 1 public campground from USGS The National Map within 5 km, including Tally Lake Campground. This is a location join, not a booking. Cabins and hotels are listed separately; campsite reservations use the official link when the source provides one.
Explore Tally Lake across LakeQuality
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Other Lakes in Montana
Oligotrophic Lakes in Montana
Where this data comes from
54 measurements from 1 monitoring station, 2012–2023. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Montana Watershed
MTWTRSHD_WQX54 samples · 2012–2023
Analytical methods
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
- 4500 N C ~ Persufate Method for Total Nitrogen
Monitoring station identifiers (1)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.
Other records on this page
Public campgrounds from USGS The National Map Structures, within about 3 miles