Incredible photos show North America's oldest lake turned bright GREEN - sparking health concerns

North America's oldest lake has turned green this month, sparking health concerns among officials.

California authorities issued a health alert Friday after the 500,000-year-old Clear Lake became infested with harmful blue-green algae.

The algae can release toxins, like microcystin, which irritate the skin and can cause kidney and liver damage if ingested.

And while the bloom is naturally occurring, it has become worst in recent years due to mining and sewage runoff. 

NASA 's Landsat 9 satellite captured an image showing North America's oldest lake had turned green (pictured)

Clear Lake is located roughly 60 miles north of San Francisco Bay and attracts a wide array of fish and birds, making it a popular location for wildlife enthusiasts, but the shallow and tepid waters also make it an ideal breeding spot for algal blooms.

Algae has an important role of keeping lakes fertile and healthy by preventing the sun's rays from reaching the lakebed which in turn, reduces the water weeds which would block out the oxygen, effectively choking the lake.

NASA, which captured the bloom from space,  reported that the poor water quality comes directly from 'run-off from nearby farms, vineyards, faulty septic systems, gravel mines, and an abandoned open-pit mercury mine.'

If there are enough pollutants in the water, blue-green algae can release microcystin when it dies, making it easy for swimmers to ingest the toxin.

When the microcystin breaks open in the stomach, it can cause serious health problems - from rashes and diarrhea to vomiting, respiratory problems, liver damage and neurological effects. 

The toxin can also lead to neurological problems when it crosses the blood-brain barrier and enters the brain.

Lake Clear (pictured) has more than 130 algae species - three of which could contain harmful toxins like mycocystin. This toxin can cause liver and kidney failure or respiratory issues

Historical accounts show that the lake was relatively clear through 1925 but an increase in 'erosion, fertilizer and wastewater discharges due to urban and agricultural development were the probable causes of increased blue-green algal growth'

As of May 25, the microcystin measurements weren't available, NASA reported, but even if the toxins aren't present in the algae, the abundance could still devastate aquatic life. 

'Bacteria consumes oxygen as they break down dead phytoplankton, which can cause hypoxia and dead zones,' NASA said.

Historical accounts show that the lake was relatively clear through 1925 but an increase in 'erosion, fertilizer and wastewater discharges due to urban and agricultural development' from that year through 1939 'were the probable causes of increased blue-green algal growth,' the Lake County government website said.

As the algae forms along the shoreline, it can start to die and decay, giving off a bright green hue and creating a sewage-like odor.

The lake has long contained high levels of algae since the last Ice Age which ended about 10,000 years ago. 

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An 1873 account from biologist Livingston Stone confirmed that the lake is no novice when it comes to algal blooms.

'It is a singular fact ... that the water of Clear Lake is never clear,' Stone told Congress at the time, according to the Lake County government website. 

'It is so cloudy, to use a mild word, that you cannot see three feet below the surface,' he said. 

'The color of the water is a yellowish brown, varying indefinitely with the varying light. The water has an earthy taste, like swamp-water, and is suggestive of moss and water plants. 

'In fact, the bottom of the lake, except in deep places, is covered with a deep, dense moss, which sometimes rises to the surface, and often to such an extent in summer as to seriously obstruct the passage of boats through the water.'

His descriptions are comparable to the conditions Clear Lake has experienced over the last 20 years as environmental conditions have worsened.

The National Oceanic and Atmospheric Administration (NOAA) warned there isn't a way to slow or stop harmful algae from growing because it is a 'natural process.'

The only steps agencies can take is to develop tools and forecasts that identify harmful blooms and the NOAA said it is already studying harmful algal blooms (HABs) to find ways 'to mitigate their effects, and to provide early warning for when and where blooms will occur.'

DailyMail.com has reached out to NASA for comment.