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[KATE FICKAS]: It's really an amazing little critter

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and it's been around for over 3 billion years.

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In 2016, Utah Lake exploded in cyanobacteria blooms.

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The problem is that many cyanobacteria produce toxins.

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[NARRATOR]: You may have heard it called "blue-green algae,"

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but it's really a kind of bacteria,

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taking in sunlight to drive photosynthesis, and giving off oxygen.

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[KATE]: It actually requires quite a bit of lab testing

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to know whether or not it's a harmful algal bloom.

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And what we're really worried about is people and pets

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ingesting that cyanobacteria.

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[NARRATOR]: Dr. Kate Fickas is a harmful algal blooms scientist

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at Utah State University.

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She helps the Utah Department of Environmental Quality

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track conditions in lakes and reservoirs.

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[KATE]: So Utah is the second dryest state in the nation.

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Most of our major lakes are actually man-made reservoirs.

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They're heavily used for recreation.

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They're heavily used for agriculture.

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And they're really important to the state, as a resource.

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[NARRATOR]: In 2017, harmful algal blooms returned to Utah Lake.

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This time, officials used satellite data to identify troubled locations.

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But how can instruments up in space

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tell us about microscopic organisms in a lake down on Earth?

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By measuring their blue-green color.

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Landsat collects light in visible and infrared wavelengths.

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Cyanobacteria reflect more green light than plain water does,

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allowing Landsat to identify algal blooms.

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[NIMA PAHLEVAN]: From satellite, what we see is, basically,

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that primary pigment, which is chlorophyll-a

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but the color, by itself, could be misleading

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a nice picture is not necessarily providing a set of quantitative data.

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[NARRATOR]: Algal blooms can look beautiful from space

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but the numbers behind the images are the important part.

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[NIMA]: Each measurement is highly accurate, and it's very,

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it's very much corresponding

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to the number of photons that are leaving the body of water

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which could be related to the biomass

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and the amount of phytoplankton

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[NARRATOR]: Dr. Nima Pahlevan is working with NASA

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and the US Geological Survey

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to make sure Landsat users have consistent, accurate,

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and ready-to-use data about lakes and rivers.

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Water is difficult to study from space,

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because only a fraction of the sunlight

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is reflected back to the satellite.

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But engineering improvements on Landsat 8

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have "levelled up" its ability

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to measure the small signals from water bodies.

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After Landsat collects the data,

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it gets beamed down to the USGS EROS center,

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where it is archived.

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The raw numbers pass through checkpoints to align the geography,

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correct for sun strength,

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and then compensate for the effects of the atmosphere.

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[NIMA]: you're essentially removing the atmospheric scattering and absorption

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[NARRATOR]: Let's break down what Nima means here.

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To measure the amount of cyanobacteria

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you need to know how much light reflected off the surface.

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But some of that light gets scattered by molecules in the atmosphere

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on the way to the satellite,

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lessening the signal received.

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And sometimes light that never made it to the surface

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gets scattered into the satellite,

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adding a false signal.

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Like removing the haze from a photograph,

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atmospheric corrections leave you with a quantitative measurement

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of exactly how much light left the water,

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known as aquatic reflectance.

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[NIMA]: You would want to look at the actual

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physical measurements to derive

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physically meaningful products from satellite data.

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[NARRATOR]: And that's the goal,

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to transform the raw materials into finished products,

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so that end users don't have to build it themselves.

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[NIMA]: by providing aquatic reflectance products,

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you're reducing, majorly reducing the burden on satellite users.

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[NARRATOR]: Although it is still provisional,

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Nima's Aquatic Reflectance Data Product

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is available for download from the USGS.

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Scientists like Kate Fickas

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convert the data product to maps showing the amount of chlorophyll-a,

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helping local officials pinpoint

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where to test for toxins and warn residents.

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[KATE]: I use Landsat and other remote sensing technology

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to help local health departments understand

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where there's a bloom,

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the magnitude of a bloom

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and the size of the bloom.

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[NARRATOR]: The spatial detail is another benefit of using Landsat data.

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Each pixel is only a 30-meter square, the size of a baseball diamond.

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Yet, it collects data across a broad area.

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In other words, there is a lot of data at a fairly high resolution.

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[KATE]: with Landsat, we can get into some of the marinas

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that are popular fishing and swimming spots,

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in order to inform local health departments

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about making public health decisions

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[NARRATOR]: For the 2017 outbreak, that's exactly what happened.

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Satellite data gave an early warning to local officials in Utah.

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The extra week of warning saved

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hundreds of thousands of dollars in health care costs.


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Monitoring algal blooms from aquatic reflectance data

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is just one example of benefits from Landsat's data products:

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wildfires,

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snow cover,

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vegetation health,

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temperature and more are available,

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for every spot on Earth.

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Landsat's highly calibrated data products,

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free to download and use,

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are making detailed Earth-observation data more accessible to users

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and bringing a greater benefit to society.

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[NASA and USGS logos]

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Landsat is a joint program of NASA and USGS