Montana’s Flathead Lake not clearest water in world

A viral put up claimed Montana’s Flathead Lake is the clearest lake on this planet. That’s false. These are the clearest lakes within the U.S. and world.

In early July, a Twitter account dedicated to science and nature posts tweeted out a image that it stated was taken from Flathead Lake, Montana, which it claimed had “the clearest water on Earth.” The tweet has since been appreciated about 400,000 instances.

Lots of the hottest replies had been from folks both posting their very own favourite clear physique of water, or debating the web page’s declare with recommendations that some place else had the clearest water on Earth.


Does Flathead Lake, Montana, have the clearest water on Earth?



No, Flathead Lake doesn’t have the clearest water of any lake on Earth. Its water isn’t even the clearest amongst American lakes.


There are a minimum of 4 lakes within the U.S. which can be clearer than Flathead Lake. The clearest lake on this planet is New Zealand’s Blue Lake, which researchers say has visibility just like pure water.

The U.S. lakes confirmed clearer than Flathead Lake are:

  • Crater Lake in Oregon
  • Waldo Lake in Oregon
  • Snow Lake in Washington state
  • Charlton Lake in Oregon

Each few years, the Environmental Safety Company (EPA) works with states, federal businesses and tribes to survey the water high quality of American lakes and streams. The latest survey from 2017 collected knowledge on over 5,000 lakes, which remains to be not each lake within the U.S., and contains knowledge on water readability.

Scientists analysis water readability utilizing an object known as a Secchi disk. Water readability is measured by dropping a Secchi disk into the water. The North American Lake Administration Society (NALMS) describes a Secchi disk as an 8 inch disk with alternating black and white quadrants. The purpose it disappears from view on the floor is named a water physique’s Secchi depth, and is how water readability is measured. An identical technique is used with an all-black disk to measure water readability horizontally in shallower our bodies of water.

Many states and nonprofit organizations additionally conduct their very own Secchi depth opinions separate from the EPA survey. Secchi depth outcomes could be variable primarily based on the obtainable gentle and day-to-day adjustments within the water readability, so measurements are usually recorded primarily based on averages.

The common Secchi depth recorded in American lakes, in line with NALMS, is lower than 11 toes.

The EPA’s newest lake survey from 2017 discovered that Flathead Lake has a Secchi depth of almost 55 toes. In accordance with Flathead Lakers, a nonprofit that works to guard the water high quality of the Flathead watershed, Secchi disk readings at Flathead Lake from 1977 to 2018 had been usually between 30 and 50 toes.

It’s the largest pure freshwater lake west of the Mississippi within the decrease 48 states. It’s positioned inside a glacier-carved valley of the Rocky Mountains, and the lake’s southern half is within the Confederated Salish and Kootenai Tribes Flathead Reservation.

Flathead Lakers say the lake’s readability is as a result of it’s comparatively low in vitamins, phosphorus and nitrogen, which promote the expansion of algae.

Clearest lake on this planet:

The clearest lake on earth is considered New Zealand’s Blue Lake. Though it’s not deep sufficient to report a Secchi depth vertically, analysis by New Zealand’s Nationwide Institute of Water and Atmospheric Analysis (NIWA) discovered that the horizontal readability of the nation’s Blue Lake is usually between 230 and 262 toes. 

NALMS says the theoretical most Secchi depth, which might be recorded in completely pure water, is 230 to 262 toes. A 260 foot depth was recorded within the ocean close to Antarctica, and a 216 foot depth was recorded within the Sargasso Sea, which is part of the Atlantic Ocean off the southeast coast of the USA.

Which means, a minimum of when wanting by the water horizontally, the lake is as clear as scientists imagine it’s attainable for water to be.

“The theoretical visibility in distilled water is about 262 toes, as estimated from one of the best obtainable instrumental measurements within the laboratory,” stated Rob Davies-Colley, a scientist who participated within the analysis. “So Blue Lake is an in depth strategy to optically pure water.”

Blue Lake, additionally known as Lake Rotomairewhenua, is positioned in Nelson Lakes Nationwide Park throughout the nation’s Southern Alps. To succeed in it requires a 4 to seven day hike from the village of St. Arnaud, the area’s improvement company says, and the lake should be handled with care as a result of it’s sacred to the native Māori folks.

“Please respect the folks of Ngāti Apa ki te Rā Tō and the purity of the water on this sacred place by not washing yourselves, your garments or your dishes within the lake,” says the Nelson Regional Improvement Company. 

Clearest lakes within the U.S.: 

Snow Lake in Washington state was the clearest lake surveyed by the EPA in 2017, though its recorded Secchi depth was not as deep as the common Secchi depth of two Oregon lakes. There isn’t obtainable knowledge on Snow Lake’s common Secchi depth. 

It’s a small lake at an altitude of over 4,000 toes within the Cascade Mountains, and is positioned simply throughout the jap boundary of King County, the place Seattle is positioned.

The lake is extra common for its close by climbing trails and fishing alternatives than it’s for the readability of its water.

Crater Lake is well-known as one of many clearest lakes within the U.S., though it was not a part of the EPA’s most up-to-date survey in 2017.

The Oregon Division of Environmental High quality (DEQ) discovered that the common Secchi depth at Crater Lake was about 102 toes from 1978 to 2019. Some Secchi disk measurements at Crater Lake have exceeded 130 toes, DEQ knowledge exhibits.

The lake, which fashioned throughout the crater of a collapsed volcano, has the report for deepest Secchi depth ever recorded inside a lake, relying on the supply. In accordance with NALMS, a Secchi depth of 144 toes recorded at Crater Lake is the report holder. This report wouldn’t embody lakes measured horizontally, akin to Blue Lake.

Crater Lake’s readability is credited to each an absence of mineral and sediment deposits, and an absence of natural materials like algae. The U.S. Division of the Inside says the lake’s water comes immediately from snow or rain and there are not any inlets to feed the lake, which implies there’s nothing to hold minerals and sediments into the lake. The Crater Lake Institute says there’s even much less natural materials absorption close to the floor of the lake than there’s in a few of the clearest, cleanest ocean waters.

The lake is throughout the Cascade Mountains on the southern finish of Oregon, south of Eugene and Bend and simply north of Medford. It sits at an elevation of over 6,000 toes — greater than a mile excessive.

A Secchi depth of simply over 70 toes was measured at Waldo Lake within the 2017 EPA survey, however the lake’s common Secchi depth was about 107 toes from 1986 to 2019, in line with DEQ.

DEQ provides Waldo Lake the sting over Crater Lake for the Secchi depth report, stating a 1938 measurement recorded a Secchi depth of 157 toes at Waldo Lake.

Waldo Lake can also be within the Cascade Mountains, and sits at an altitude of 5,400 toes. It’s throughout the Willamette Nationwide Forest, north of Crater Lake, between Eugene and Bend.

Charlton Lake can also be an Oregon lake. The 2017 EPA survey recorded a Secchi depth of 64 toes at Charlton Lake, the third deepest Secchi studying within the survey. 

Charlton Lake is very like Snow Lake in that it’s a small lake extra well-known for close by climbing trails than it’s for water readability. There isn’t any common Secchi depth knowledge obtainable for Charlton Lake.

It’s positioned lower than two miles east of Waldo Lake, nonetheless throughout the southern finish of the Cascade Mountains. It sits barely larger than Waldo Lake at a peak of 5,692 toes, which means all three Oregon lakes listed are over a mile excessive.

There are not any year-round floor streams that circulate into Charlton Lake, the Atlas of Oregon Lakes says; water as an alternative flows into the lake from snowmelt runoff and intermittent, momentary streams.

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