Located in Lincoln County, Montana, Lake Koocanusa is a lake. It sits roughly 40 km (25 mi) NNW of Eureka.
Lake Koocanusa ( koo-kuh-NYOO-suh) is a reservoir in British Columbia (Canada) and Montana (United States) formed by the damming of the Kootenai River by the Libby Dam in 1972. The dam was formally dedicated by US President Gerald Ford on August 24, 1975. The lake is formed north of the dam, reaching 48 miles (77 km) to the Canada–United States border and 42 miles (68 km) further into British Columbia. The lake holds 13% of the water in the Columbia River system. The town of Rexford was moved, as well as the Great Northern Railway line. The town of Waldo, British Columbia, is now covered by the lake. What was once a barrier to river travel, Jennings Canyon is now inundated by the lake. The Elk River joins the Kootenay River in the northern part of Lake Koocanusa, within Canadian territory. Lake Koocanusa was named in a contest won by Alice Beers of Rexford, Montana. The name is a...From the Wikipedia article “Lake Koocanusa”, licensed under CC BY-SA 4.0.
Sunrise & sunset directions
At Lake Koocanusa the sunrise point swings a long way through the year: about 51° (NE) at the June solstice and 127° (SE) in late December. Sunset moves from 309° (NW) in June to 234° (SW) in December, and the midday sun climbs to 64° in summer but only 17° in winter.
| Date | Sunrise | Azimuth | Sunset | Azimuth | Noon sun | Daylight |
|---|---|---|---|---|---|---|
| March equinox (Mar 20) | 7:45 AM | 89° E | 7:54 PM | 271° W | 41° | 12h 09m |
| June solstice (Jun 21) | 5:36 AM | 51° NE | 9:51 PM | 309° NW | 64° | 16h 14m |
| September equinox (Sep 22) | 7:28 AM | 89° E | 7:41 PM | 271° W | 41° | 12h 13m |
| December solstice (Dec 21) | 8:34 AM | 127° SE | 4:46 PM | 234° SW | 17° | 8h 11m |
Azimuth is measured clockwise from true north (90° = east, 270° = west). Computed for 2026; values change by less than a degree from year to year.
Golden hour & blue hour by month
Lakes reflect best in calm air — usually the first hour after sunrise, before breezes ripple the surface.
| Month (15th) | Blue hour starts | Sunrise | Golden hour ends | Golden hour starts | Sunset | Blue hour ends | Daylight |
|---|---|---|---|---|---|---|---|
| January | 7:55 AM | 8:31 AM | 9:24 AM | 4:18 PM | 5:11 PM | 5:47 PM | 8h 40m |
| February | 7:18 AM | 7:51 AM | 8:36 AM | 5:16 PM | 6:01 PM | 6:34 PM | 10h 10m |
| March | 7:24 AM | 7:55 AM | 8:37 AM | 7:04 PM | 7:46 PM | 8:18 PM | 11h 51m |
| April | 6:16 AM | 6:50 AM | 7:33 AM | 7:50 PM | 8:33 PM | 9:07 PM | 13h 43m |
| May | 5:20 AM | 5:59 AM | 6:46 AM | 8:31 PM | 9:18 PM | 9:56 PM | 15h 19m |
| June | 4:53 AM | 5:36 AM | 6:26 AM | 8:58 PM | 9:49 PM | 10:32 PM | 16h 13m |
| July | 5:12 AM | 5:53 AM | 6:41 AM | 8:54 PM | 9:42 PM | 10:23 PM | 15h 50m |
| August | 5:58 AM | 6:34 AM | 7:18 AM | 8:15 PM | 8:59 PM | 9:34 PM | 14h 25m |
| September | 6:46 AM | 7:18 AM | 8:00 AM | 7:14 PM | 7:56 PM | 8:28 PM | 12h 38m |
| October | 7:30 AM | 8:02 AM | 8:46 AM | 6:09 PM | 6:52 PM | 7:24 PM | 10h 50m |
| November | 7:17 AM | 7:52 AM | 8:42 AM | 4:11 PM | 5:01 PM | 5:36 PM | 9h 09m |
| December | 7:53 AM | 8:30 AM | 9:26 AM | 3:48 PM | 4:44 PM | 5:21 PM | 8h 13m |
Local time (America/Denver), including daylight saving time. Golden hour runs from about −4° to +6° solar altitude, so the morning golden hour begins during blue hour, before sunrise.
Milky Way & night sky
From Lake Koocanusa, the Milky Way core is visible in a dark sky from May through June. June gives the longest window (about 2.3 hours on a moonless night), and the core peaks around 12° above the southern horizon. Our light-pollution model puts the sky at about Bortle 1 (excellent dark-sky site), which is excellent for astrophotography.
| Month | Core visible (15th) | Hours | Max altitude | Direction |
|---|---|---|---|---|
| January | Below 10° in darkness | — | -6° | — |
| February | Below 10° in darkness | — | 4° | — |
| March | Below 10° in darkness | — | 8° | — |
| April | 4:43 AM – 4:43 AM | 0.0 | 10° | SSE → SSE |
| May | 2:44 AM – 3:14 AM | 0.5 | 11° | SSE → S |
| June | 12:44 AM – 3:04 AM | 2.3 | 12° | SSE → SSW |
| July | 12:48 AM – 1:08 AM | 0.3 | 11° | SSW → SSW |
| August | Below 10° in darkness | — | 10° | — |
| September | Below 10° in darkness | — | 7° | — |
| October | Below 10° in darkness | — | 3° | — |
| November | Below 10° in darkness | — | -5° | — |
| December | Below 10° in darkness | — | -20° | — |
Window when the galactic core is at least 10° high during astronomical darkness on the 15th of each month. Pick nights within a few days of the new moon. Plan exact nights with the Milky Way planner.
Estimated sky darkness: 1 Bortle 1 — Excellent dark-sky site. The Milky Way casts faint shadows; zodiacal light and airglow are obvious. Modeled zenith brightness ≈ 21.94 mag/arcsec². Aurora needs roughly Kp 3.5+ to show low on the northern horizon here.
Weather & best season
Long-term NASA satellite data for this area show July as the clearest month (about 44% average cloud cover) and November as the cloudiest (76%). July is the warmest month and December the coldest, which matters for gear, snow access and how long batteries last at night.
Average cloud cover (%)
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| High °F | 36 | 46 | 60 | 71 | 83 | 94 | 96 | 96 | 89 | 78 | 53 | 38 |
| Low °F | -34 | -31 | -26 | 1 | 22 | 27 | 35 | 35 | 21 | 5 | -30 | -36 |
| Precip. (in) | 1.9 | 1.7 | 2.2 | 1.8 | 2.3 | 2.9 | 1.2 | 1.1 | 1.7 | 1.8 | 2.4 | 2.2 |
Monthly climatology for the surrounding 1° grid cell from NASA POWER (MERRA-2). Mountain sites can be colder and cloudier than the cell average.
Photography tips for this lake
- Include shoreline rocks, reeds or a log as foreground to give the reflection depth.
- Expose for the brighter sky; reflections are typically half a stop to a stop darker.
- After sunset, long exposures smooth wind ripples into glass.
- For mirror reflections, get low and close to the water; the reflection grows with a lower camera.
- A polarizer can remove reflections to show the lakebed — or keep them, depending on rotation.
- Bring a spare battery — cold weather and long exposures drain them fast.
Season: Autumn mornings bring mist and fall color; high-elevation lakes are usually ice-free only from early summer to mid-autumn.
Suggested gear: Tripod, Circular polarizer, Wide-angle lens, Waterproof boots. Work out exposures with the depth of field, ND filter and NPF rule calculators.
Campgrounds nearby (Recreation.gov)
FAQ
When is the best time to photograph Lake Koocanusa?
What time is golden hour at Lake Koocanusa?
Where does the sun rise and set at Lake Koocanusa?
Can you see the Milky Way from Lake Koocanusa?
Do you need a permit to photograph at Lake Koocanusa?
How far is Lake Koocanusa from Eureka?
Sources
Location data: Wikidata, Wikipedia. Sun, moon and Milky Way times are computed by LWPhoto Atlas for 2026. Climate: NASA POWER. Sky darkness is a population-based estimate (Walker's law), not a measurement. See data sources & licenses.