RESTON, Va. — The U.S. Geological Survey (USGS) will invest more than $2 million to map critical mineral resources in central Minnesota in partnership with several Minnesota state partners.  

Original Article

Midcontinent Region

Midcontinent Region

https://www.usgs.gov/news/national-news-release/usgs-partners-minnesota-map-critical-mineral-potential-cutting-edge-0?utm_source=comms&utm_medium=rss&utm_campaign=news

apdemas@usgs.gov

RESTON, Va. — The U.S. Geological Survey (USGS) will invest more than $2 million to map critical mineral resources in central Minnesota in partnership with several Minnesota state partners.  

Original Article

Midcontinent Region

Midcontinent Region

https://www.usgs.gov/news/national-news-release/usgs-partners-minnesota-map-critical-mineral-potential-cutting-edge-data?utm_source=comms&utm_medium=rss&utm_campaign=news

apdemas@usgs.gov

RESTON, Va. — The U.S. Geological Survey will invest more than $3.5 million to map critical mineral resources in partnership with the geological surveys of Arkansas, Kentucky, Illinois, Indiana, Missouri and Tennessee.

Original Article

Midcontinent Region

Midcontinent Region

https://www.usgs.gov/news/national-news-release/usgs-partners-six-states-map-critical-mineral-potential-cutting-edge?utm_source=comms&utm_medium=rss&utm_campaign=news

apdemas@usgs.gov

Editor: In the public interest and in accordance with Federal Aviation Administration regulations, the USGS is announcing this low-level airborne project. Your assistance in informing the local communities is appreciated.

Original Article

Midcontinent Region

Midcontinent Region

https://www.usgs.gov/news/state-news-release/media-alert-low-level-flights-image-geology-over-parts-arkansas-illinois?utm_source=comms&utm_medium=rss&utm_campaign=news

apdemas@usgs.gov

 Editor: In the public interest and in accordance with Federal Aviation Administration regulations, the USGS is announcing this low-level airborne project. Your assistance in informing the local communities is appreciated. 

Original Article

Midcontinent Region

Midcontinent Region

https://www.usgs.gov/news/state-news-release/media-alert-low-level-airplane-flights-image-geology-over-parts-minnesota?utm_source=comms&utm_medium=rss&utm_campaign=news

apdemas@usgs.gov

RESTON, Va. — The U.S. Geological Survey (USGS) and a coalition of state geological surveys are investing about $325,000, to conduct geochemical sampling in across about 2 million square kilometers of the central United States, from the Midcontinent to the Appalachian Basin.

Original Article

Region 3: Great Lakes

Region 3: Great Lakes

https://www.usgs.gov/special-topics/bipartisan-infrastructure-law-investments/news/bipartisan-infrastructure-law-14?utm_source=comms&utm_medium=rss&utm_campaign=news

apdemas@usgs.gov

RESTON, Va. — The U.S. Geological Survey (USGS) and the Michigan Geological Survey are investing $300,000 in mapping the Upper Peninsula of Michigan, one of the most historically important areas of U.S. mineral production for the past 175 years, with copper from the Keweenaw district and White Pine deposit, and iron from the Marquette, Menomonie, and Gogebic iron ranges.

Original Article

Region 3: Great Lakes

Region 3: Great Lakes

http://www.usgs.gov/special-topics/bipartisan-infrastructure-law-investments/news/bipartisan-infrastructure-law-funds-6?utm_source=comms&utm_medium=rss&utm_campaign=news

apdemas@usgs.gov

RESTON, Va. — The U.S. Geological Survey (USGS) and the Illinois State Geological Survey are investing about $525,000 to  map the Illinois-Kentucky Fluorspar District and the Midwest Permian Ultramafic District, which are locations of proven critical mineral resources and were a major source of fluorspar prior to the 1970s.

Original Article

Region 3: Great Lakes

Region 3: Great Lakes

http://www.usgs.gov/special-topics/bipartisan-infrastructure-law-investments/news/bipartisan-infrastructure-law-funds-3?utm_source=comms&utm_medium=rss&utm_campaign=news

apdemas@usgs.gov

The U.S. Geological Survey has finalized an agreement with a consortium of eight universities and natural resource organizations to form the Midwest CASC. 

The Midwest CASC consortium will be hosted at the University of Minnesota’s Institute on the Environment and will include the University of Wisconsin, the College of the Menominee Nation, the Great Lakes Indian Fish and Wildlife Commission, Michigan State University, Indiana University, the University of Illinois and the Nature Conservancy. Member organizations were selected after an open competition and extensive review by scientific experts. 

“In order to address the climate crisis, we need to be guided by the best available science. Integrated collaboration with educational and natural resource organization partners ensures that federal, Tribal and state resource managers have access to the collective wisdom of world renowned experts. The Midwest Climate Adaptation Science Center will better position us to mitigate climate impacts while focusing needed attention to Tribal and state resources that are particularly vulnerable to climate change,” said Secretary of the Interior Deb Haaland. 

“We are excited to bring climate-focused innovation and scholarship to America’s heartland, where the next generation of students stands ready to tackle the challenges facing the Great Lakes, mighty rivers, fertile prairies and abundant natural resources of the region,” said Doug Beard, USGS National Chief of Climate Adaptation Science Centers. 

The Midwest CASC will support management and protection of land, water and natural resources with actionable climate science, innovation and decision support tools. It will pay special attention to Tribal concerns and build off the unique and robust experience of Midwest Tribes with adaptation science and practice. This includes a fellowship program for graduate students and a summer research experience for undergraduates focused on Tribal participation. Another focus will be the interplay of natural resources, forestry, streams and wetlands, with agricultural and urban areas, land uses that are prominent in the Midwest.  

The partnership will be effective immediately, with a formal ribbon cutting celebration planned on the University of Minnesota-Twin Cities campus later this fall. 

About CASCs 

Climate Adaptation Science Centers are each hosted by a public university, composed of a multi-institution consortium and managed by the National CASC that oversees the nationwide network and pursues multi-region projects of national significance. These partnerships ensure access to a broad range of scientific expertise, production of high-quality science and sharing of funds, resources and facilities. University involvement also allows the CASCs to introduce students to the idea of “co-producing” science, in which scientists and decision-makers work closely together to ensure scientific research and products are usable and directly address real-world problems. Learn more about the history of CASCs

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Original Article

USGS News: Region 3: Great Lakes Region

USGS News: Region 3: Great Lakes Region

https://www.usgs.gov/news/department-interior-announces-host-midwest-climate-adaptation-science-center

apdemas@usgs.gov

WASHINGTON - The Department of the Interior today announced the location of the newest Climate Adaptation Science Center (CASC), the ninth and final CASC in the national network dedicated to providing science to help managers of the country's fish and wildlife resources adapt to climate change. 

Original Article

Region 3: Great Lakes

Region 3: Great Lakes

http://www.usgs.gov/news/national-news-release/department-interior-announces-host-midwest-climate-adaptation-science

apdemas@usgs.gov

The idea for Landsat began in 1966, three years before Apollo 11 landed on the Moon.  At that time, the Department of the Interior and NASA announced plans for a civilian satellite that would focus specifically on Earth imagery. In 1972, the same year the famous Blue Marble image was taken by Apollo 17, NASA launched the first satellite of the Landsat program. Landsat, a joint effort of the USGS and NASA, has produced the longest, continuous record of Earth’s land surface as seen from space.

A timelapse of the coast of Chatham, Massachusetts, showing the changing shoreline. Created with Landsat imagery using Google Earth 3D Timelapse. Courtesy of Google. (Timelapse courtesy of Google)

We’re now on Landsat 8 (with Landsat 7 still in orbit and continuing to acquire images), and NASA plans on launching Landsat 9 this September. As the technology deployed by Landsat advances, the uses for Landsat imagery also advance. On April 15, 2021, Google announced its Google Earth 3D Timelapse tool, which is based on imagery from Landsat, along with other imagery from NASA, the European Commission, and the European Space Agency. Timelapse allows users to access powerful 3D visuals to study our planet’s stories and consider actions regarding climate change, sustainable development and much more.

To celebrate Earth Day, we thought we would share some of the uses of Landsat imagery throughout the decades, and we also want to highlight Landsat’s beautiful imagery of the Earth.

A series of USGS Landsat images shows deforestation near Santa Cruz, Bolivia, from 1986 to 2016.

Focus on the Forests

Graceful and majestic, forests have long held humanity’s imagination and been synonymous with the health of the environment. Through Landsat, the USGS has been studying the world’s forests and various factors that have affected them.

From the ground, the extent of forestland damage may simply be too large for field observers to quantify. But 438 miles above the Earth, Landsat satellites pass over every forest in the country dozens of times a year—every year—creating a historical archive of clear, composite images that tells the hidden stories of life and death in our nation’s forests. From pine beetles to the hemlock woolly adelgid, forest damage from invasive species is tracked by Landsat so forest managers can identify and quantify the impacts and develop effective mitigation strategies.

Unfortunately, it’s not just insects that are affecting our forests. Human-caused deforestation is a worldwide issue. In 2013, the first global image maps of tree growth and disappearance were published using data exclusively from the Landsat 7 satellite. The uniform data from more than 650,000 scenes, spanning the years 2000–2012, ensured a consistent global perspective across time, national boundaries, and regional ecosystems.

Our Dynamic Planet 

The New York City Council’s Data Team used Landsat 8 data to create an interactive map showing temperature differences throughout the city. (courtesy council.nyc.gov)

(Public domain.)

It is not just forest landscapes that change over time. In the past 50 years, cities have grown, farmlands have expanded, wilderness has shrunk, and glaciers have retreated, all under Landsat’s watchful gaze. Through Landsat imagery, scientists and decisionmakers can see where land usage has changed and to what purpose it is currently being put.

Idaho, for example, has emerged as the second-leading state for irrigation usage behind California, and they needed a way to keep tabs on their water usage. After all, Idaho is not known for its high rainfall. Landsat’s eye in the sky has helped Idaho’s resource managers account for and track how much water they have and how much water they use each year for irrigation.

In another example of Landsat assisting with water usage, Canada and the United States share the St. Mary and Milk River system in Alberta and Montana. Apportioning water between the two countries, as well as the Blackfeet Nation, which also uses water from the rivers, can be a challenge, because irrigation and evapotranspiration are difficult to track using traditional methods. However, scientists from Canada and the United States were able to figure out how to use Landsat to get a much clearer idea of the amount of water actually being taken out of the rivers, either by human activities or other natural processes.

In the United States and around the world, cities are growing. The USGS seeks to illustrate and explain the spatial history of urban growth and corresponding land-use change. Scientists are studying urban environments from a regional perspective and a time scale of decades to measure the changes that have occurred in order to help understand the impact of anticipated changes in the future.

One example of how Landsat is aiding city planners lies in addressing areas of extreme heat that develop in cities during the summer. In New York City, planners and health officials were able to use Landsat to identify which neighborhoods had the worst hot spots and even track what effects their mitigation efforts had.

Landsat Burned Area Example

See the Landsat Science Products page for more details.

(Public domain.)

Watching over the World

The power of observation through Landsat is not just used to watch over environmental impacts and land-use change. The imagery is also brought to bear during natural hazard events. From hurricanes to wildfires to volcanoes, Landsat has helped responders during the events and has supported rebuilding efforts after the fact.

Landsat goes beyond the United States. The USGS Landsat program is part of the International Charter "Space and Major Disasters,” which serves as an important source of satellite imagery for responding to major natural and man-made disasters worldwide. The Charter comprises 17 member agencies from countries around the world and has been activated more than 700 times in the 20 years it has been in effect.

A serene gradient from red to smoky blue-gray seems to mask a chaotic scene underneath, expressing a wide range of emotion. Looking like a NASA closeup of Jupiter, this image reveals sediment in the Gulf of Mexico off the Louisiana coast.

Source: Landsat 8 Download Imagery (Public domain.)

Work of Art

With all its uses, it’s no wonder that Landsat is treasured by both USGS scientists and its users outside the agency. Also, studies have shown it provides billions of dollars of value to people around the world. But one of the unanticipated benefits of Landsat is that the imagery allows us to see the Earth’s natural beauty from a perspective that only astronauts get.  And on this Earth Day, we wanted to share the beauty of the images it produces. USGS scientists have been so captivated by the views of Landsat that they have created a regular series, called Earth As Art. So, as you enjoy Earth Day 2021, enjoy the Earth as seen by the world’s longest continually operating Earth observation program!

Original Article

USGS News: Region 3: Great Lakes Region

USGS News: Region 3: Great Lakes Region

https://www.usgs.gov/news/celebrating-earth-day-above

apdemas@usgs.gov

Happy Earth Day! As we celebrate our wonderful planet and the fascinating things we learn about it every year, we wanted to share a unique view of the Earth, provided by the longest continuously running Earth-observing satellite program: Landsat.

Original Article

Region 3: Great Lakes

Region 3: Great Lakes

http://www.usgs.gov/news/featured-story/celebrating-earth-day-above

apdemas@usgs.gov

The Marcellus Shale and Point Pleasant-Utica Shale formations of the Appalachian Basin contain an estimated mean of 214 trillion cubic feet of undiscovered, technically recoverable continuous resources of natural gas, according to new USGS assessments.

Original Article

Region 3: Great Lakes

Region 3: Great Lakes

http://www.usgs.gov/news/national-news-release/usgs-estimates-214-trillion-cubic-feet-natural-gas-appalachian-basin

apdemas@usgs.gov

Meet the Midcontinent Rift, one of the most geologically fascinating regions in the United States and Canada.(Public domain.)

Now, you too can learn some of that history and see a small part of the mineral potential of the United States without leaving your comfortable chair! The USGS has just released a new interactive Story Map describing the Mineral Deposits of the Midcontinent Rift System.

The Midcontinent Rift System, which curves for more than 2000 km across the Upper Midwest, is one of the world’s great continental rifts. Rifting began about 1.1 billion years ago, when the Earth’s crust began to split along the margin of the Superior craton. Rifting ended before the crust completely opened to form a new ocean, and as time passed rift rocks were buried beneath younger rocks. With erosion and glaciation, the ancient rocks of the Midcontinent Rift were exposed in the Lake Superior region, creating much of its spectacular shoreline.

Learn the geologic history behind the mining history in the Great Lakes.(Public domain.)

In the Lake Superior region, rocks of the rift contain a wealth of mineral resources that formed by magmatic and hydrothermal processes during the ~30 million year course of rift development. Rift rocks are host to Michigan’s storied native copper deposits, and contain significant copper and nickel that were deposited during various stages of rift development.

In this Story Map, mineral deposit locations and descriptions, compiled from the USGS Mineral Resource Data System and the Ontario Geological Survey Mineral Deposit Inventory, are categorized by mineral commodity, mineral deposit type, and the relative time frame of mineralization.

The Midcontinent region is the focus of active mineral exploration, including for mineral deposit types previously unrecognized there.  Here, USGS scientists Laurel Woodruff and Suzanne Nicholson visit an anorthosite quarry, Duluth Complex, MN. Photo by K. Schulz, USGS.(Credit: Klaus, Schulz. Public domain.)

This Story Map also describes a new comprehensive digital Geographic Information System for the Midcontinent Rift System recently compiled by the USGS from numerous regional studies conducted over the last several decades.

Characterizing the mineral resources of the Midcontinent Rift System is a priority of the USGS Mineral Resources Program, and we hope you enjoy this Story Map that tells just part of the amazing story of this important geologic feature.

Much of the Great Lakes' mineral wealth can be traced to the Mid-Continent Rift. Here is a generalized geologic map of the Midcontinent Rift System. Modified from Dean Peterson, Duluth Metals.(Public domain.)

Read More:

Multidisciplinary Studies to Image and Characterize the Mineral Resource Potential of the Midcontinent Rift, USA Geophysics of the Midcontinent Rift Region Characterization of the Midcontinent Region Mineral Resources

Original Article

USGS.gov

USGS.gov

https://www.usgs.gov/news/understanding-mineral-resources-midcontinent-rift

apdemas@usgs.gov

The first great geologic expeditions of the United States set off in the mid-1800s, equipped with mules, rifles, and early scientific instruments. Their goal: to uncover the great mineral wealth of the United States and learn about its earliest geologic history.

Original Article

Wisconsin

Wisconsin

http://www.usgs.gov/news/science-snippet/understanding-mineral-resources-midcontinent-rift

apdemas@usgs.gov

Fortunately, in an effort with needlepoint detail, the U.S. Geological Survey has stitched together geologic maps of the Lower 48 States, providing a seamless quilt of 48 State geologic maps that range from 1:50,000 to 1:1,000,000 scale.

The new product, called the USGS State Geologic Map Compilation, is a database compilation based on the Preliminary Integrated Geologic Map Databases for the United States. It provides a standardized Geographic Information System format that allows users to more readily conduct spatial analyses of lithology, age, and stratigraphy at a national-scale. As an example, a named rock unit (Dakota sandstone) might be called something different from State to State, on their respective State geologic maps. In the new database, rock units are characterized by their type (lithology) like "sandstone or granite" not by their formal name. This consistency across the single database now makes it easier for users to access information, rather than having to collect it from multiple databases.

One Database, Many Users

The shale oil boom: how much oil is really there? Critical minerals: does the United States have what it needs for your smartphone, air conditioner and car, let alone our military? Earthquakes and volcanoes: which hazards do we face? All these questions are addressed with geologic maps!

Geologic information forms the bedrock of much of the work USGS does. On the traditional geologic research side, these data will inform assessments of energy and mineral resources, quantifying volcano and earthquake hazards, and mitigation of potential environmental effects from mining.

However, high-quality geologic maps and their underlying databases extend beyond the obvious links. Tracking groundwater—an important source of drinking water and irrigation to millions in the United States—requires accurate data about rock formations and faults (the groundwater’s plumbing, as it were). In addition, understanding the nature of geologic formations can assist with infrastructure development, such as where to put dams and bridges, as well as agricultural planning.

Finally, a national digital geologic map database is vital to those who use other national-scale datasets, such as geochemistry, remote sensing, and geophysical data. Trying to match a national-scale dataset with a dataset of just Mississippi, for instance, would open the door to confusion, mistakes, and some serious Delta blues.

A screenshot of the State Geologic Map Compilation, showing the layer navigation menu. (Public domain.)

New Maps, New Data, and Easier to Use

The State Geologic Map Compilation includes the following seven new State geologic maps that have been released since the original Preliminary Integrated Geologic Map Databases were published: Idaho, Illinois, Iowa, Minnesota, Montana, Nevada, and Vermont. The State Geologic Map Compilation also incorporates new supplemental data for the States of California, Indiana, New Jersey, New Mexico, and North Carolina. In addition, the surface geologic maps for North Dakota and South Dakota have been replaced with updated bedrock geologic maps.

We corrected numerous errors and added enhancements to the preliminary datasets using thorough quality assurance/quality control procedures. We ensured attributes adhered to data dictionaries created for the compilation process and corrected spatial and topological errors. Also, we have standardized the geologic data contained in each State geologic map to allow spatial analyses of lithology, age, and stratigraphy at a national scale.  

The changes make the data more consistent between the States as well as with the original State geologic maps. It also streamlines tasks that previously required combining multiple geographic information system datasets and tables.

Stitching the Pieces Together

This new product is like a quilt, with a top layer that is pieced together from many pieces of cloth and a single piece of cloth underneath that forms the backing. In our analogy, the top layer is a GIS map layer that stitches together individual state geologic maps to form a national map, and the bottom layer (or backing) is a single consistently formatted database that means each of the pieces on top have the same structure underpinning them. Now that a newly updated, single database (backing) is holding all the information, multiple individual pieces can be viewed and queried as a whole.

Prior to the State Geologic Map Compilation, we had standardized individual GIS databases for each state, but none of them were connected. Anytime someone wanted to do national or regional scale work, they had to go to multiple databases, then piece what they wanted together.  The improvements to this updated version create a single, conterminous State geologic map database.

Series of images that show how users of the State Geologic Map Compilation can zoom in from broad national scale to more a detailed local scale. The more detailed image is of the Bingham canyon mine area in Utah. (Public domain.)

Putting Geology on the Map

For the visual learners out there, map services of the State Geologic Map Compilation data have been created which can be used in numerous web mapping applications including the USGS National Map. This allows the data to be explored without specialized geographic information systems software.  To use it, go here, then use the “Add Data” button on most web mapping applications to access the data in web browsers.

The State Geologic Map Compilation map service has also been added to the National Map of Surficial Mineralogy web mapping application [Layers List - "Lithology (State Geologic Maps)" and "Geologic Structure (State Geologic Maps)"]. Users can explore the data along with the other layers including remote sensing (ASTER and Landsat7), various mineral deposits data, and numerous types of basemap data.

Out of Many, One...Database, That Is

Just as quilts are rarely the work of a single needle, this mosaic of geologic maps and data was sewn by many hands. The State Geologic Map Compilation of the Conterminous United States was developed by the USGS Mineral Resources Program. The project owes its success to numerous USGS Mineral Resources Program staff who originally compiled the Preliminary Integrated Geologic Map Databases for the United States as well as the foundational geologic mapping work completed by U.S. State Geologic Surveys and academia.  Special thanks to the Montana Bureau of Mines & Geology for their tremendous work in preparing the Geologic Map of Montana to be included in the State Geologic Map Compilation.

A screenshot of the State Geologic Map Compilation. (Public domain.)

What’s Next?

As mentioned previously, one limitation of the State Geologic Map Compilation is that geologic units haven’t been integrated across state boundaries. That means that, in some locations, a geologic formation that spans the border of, say, Colorado and Kansas might be represented by polygons with different names in Colorado and Kansas. We preserve what the States named each rock unit, then we use a standardized rock coding to show what kind of rock the unit is, regardless of what it is named. So now, for instance, if you wanted, you could look for every shale formation in the Lower 48 that was the same age as the oil-rich Bakken Formation of North Dakota and Montana.

A long-term goal of the USGS is eventually to have a fully integrated geologic map at useful scales of the entire country. That map and its underlying databases would be invaluable to Federal, State, and local government, as well as private companies and academia. It would greatly enhance studies of mineral resources, groundwater resources, geologic natural hazards, and aspects of environmental health, as well as agricultural and infrastructure planning. It is no exaggeration to say it could serve as the foundation for a renaissance in Earth science in the United States.

Original Article

USGS.gov

USGS.gov

https://www.usgs.gov/news/stitching-together-new-digital-geologic-quilt-united-states

apdemas@usgs.gov

A carbonatite here, a glacial moraine there, a zig-zagging fault or two, even a behemoth of a batholith. The geology of the 50 States is an enormous patchwork of varied forms, beautiful in their variance but challenging to present as a single map.

Original Article

Wisconsin

Wisconsin

http://www.usgs.gov/news/featured-story/stitching-together-new-digital-geologic-quilt-united-states

apdemas@usgs.gov

Image of the VTEM Plus AEM system from Geotech Ltd. in flight. A similar system will be flown during the upcoming USGS AEM study.
(Public domain.)

Yes, 10,000 feet in the air might not be where you’d expect to find underground mineral research being done, but believe it or not, this is an important part of figuring out where mineral deposits might be found.

When we’re up there, we’re looking for all kinds of things that help us determine what kinds of minerals might exist in an area. One thing we often measure for is the magnetic properties of the rock layers we fly over.

You’ve probably heard that some metals are magnetic, like iron or nickel. But another, very valuable set of minerals can be found by looking for magnetism: rare-earth elements. Most of our modern electronics depend on rare-earth elements, and the United States imports 100% of the amount we use each year, so finding where they might be in the United States is an important goal of ours. We’ve conducted these flights over the Upper Midwest, Iowa, Missouri and even Upstate New York.

The airplane that will be doing overflights in Essex and Clinton Counties, flying a grid pattern at low altitude for a few weeks in December. 
(Public domain.)

Another tool we use to study the mineral potential of the country is hyperspectral imaging. Basically, we use lasers to create a map of different signatures, and then compare them to the signatures for certain rock types that contain valuable minerals. The primary places USGS has used hyperspectral imaging to study minerals are Alaska and Afghanistan.

So if you look up one day and see a small plane flying back and forth along a grid, or see a helicopter dragging a couple of hula hoops around, check your local paper to see if it’s us seeing what kind of minerals might be in your backyard!

Original Article

USGS.gov

USGS.gov

https://www.usgs.gov/news/air-look-deep-underground

apdemas@usgs.gov

The first-ever National Lakes Assessment of toxins from harmful algal blooms challenges several long-held assumptions, including the extent, distribution and make-up of toxins from harmful algal blooms. The assessment, conducted by the U.S. Geological Survey and U.S. Environmental Protection Agency, sampled 1161 inland lakes and reservoirs throughout the United States.

Harmful algal blooms can be caused by numerous species of algae and bacteria, but this assessment focused on those caused by cyanobacteria, which are also known as blue-green algae. Toxins produced by cyanobacteria are known to have a range of lethal and non-lethal effects on humans, wildlife and companion animals. Additionally, cyanotoxins have been shown to accumulate at all levels of aquatic food webs in lakes and reservoirs, from plankton all the way up to top-level predators.

 “Some had believed that toxic cyanobacterial harmful algal blooms were just a local or regional occurrence, but this study shows that they are distributed in lakes throughout the nation.” said USGS scientist Keith Loftin, lead author on the assessment.

This map shows all of the lakes tested and those in which samples contained cylindrospermopsin toxins.

The assessment sampled for three types of cyanobacterial toxins, also known as cyanotoxins: cylindrospermopsins, microcystins and saxitoxins. Results found cylindrospermopsins in 4.0 percent of samples; microcystins in 32 percent and saxitoxins in 7.7 percent.

 “This assessment shows that multiple classes of cyanotoxins are present in lakes in diverse settings throughout the United States,” said Loftin. “This is a significant finding given the perception that cyanobacteria blooms are increasing in frequency and severity.”

Typically, studies done for harmful algal bloom event response programs are largely focused on near-shore areas, where harmful algal blooms can be very thick and recreational activities include swimming or fishing from shore.  In contrast, the National Lakes Assessment focused on samples collected in the center of lakes, where cyanobacteria and toxin concentrations can be much lower, and other types of recreational activities are more common, such as boating. 

In addition, most studies for cyanotoxins only look for microcystins, not saxitoxins or cylindrospermopsins.  The results of the assessment, however, show that saxitoxins and cylindrospermopsins can occur at significant levels too.

This map shows all of the lakes tested and those in which samples contained saxitoxin toxins.

“Algal toxins like these microcystins can be a serious issue, especially in regard to the water we use for recreation or drinking,” said Michael Focazio, program coordinator for the USGS Toxic Substances Hydrology Program. “For instance, in 2014 the City of Toledo, Ohio, alerted approximately 500,000 people that their drinking water supply was contaminated by microcystins.  That event drew national attention to the potential vulnerabilities of our water resources to toxins formed in association with harmful algal blooms.”

Studies focused on microcystins because they occur the most frequently, and it was assumed that they were a good indicator of the presence of other toxins. However, this assessment discovered that cylindrospermopsins were found alongside microcystins in 0.96 percent of samples and saxitoxins were found alongside microcystins in 5.0 percent of samples.  In fact, all three classes of toxins were found together in only 0.32 percent of samples. 

This shows that testing for microcystins alone is not a good way of showing that saxitoxins or cylindrospermopsins are present, Loftin said. He noted that relying on testing only for microcystins may lead to scenarios where potential risks from other cyanotoxin classes are unassessed in microcystin-only monitoring plans. 

This map shows all of the lakes tested and those in which samples contained microcystin toxins.

Additionally, this study highlighted that testing for the presence of chlorophyll to show how much microcystin might be present is not reliable either. Chlorophyll is a green pigment that is associated with photosynthetic organisms such as cyanobacteria. 

Current provisional World Health Organization recreational health risk indicators for protection against microcystins suggest using the amount of chlorophyll to gauge how much microcystin might be present. However, the National Lakes Assessment discovered that relying on chlorophyll that way overpredicted microcystin risk.

This assessment was performed as part of ongoing USGS research on the occurrence and factors that influence or create new environmental exposure pathways of cyanobacteria and associated algal toxins to aquatic ecosystems.

The present study provides new evidence of the widespread occurrence of cyanotoxins in the ambient water resources of the United States and highlights the importance of understanding factors associated with microcystin and other cyanotoxin occurrence.  Ongoing work by the USGS in the Pacific Northwest and planned work in the northeastern United States and California will expand the understanding of cyanobacteria and toxins in stream ecosystems. 

The assessment can be accessed here. More information on this project and other USGS research on environmental health and water quality can be found at the USGS Toxic Substances Hydrology Program, the USGS Environmental Health Mission Area, and the USGS National Water Quality Assessment Program. To keep up-to-date on the latest USGS environmental health research, subscribe to the USGS GeoHealth Newsletter.

Original Article

USGS.gov

USGS.gov

https://www.usgs.gov/news/new-science-challenges-old-assumptions-about-harmful-algal-blooms

apdemas@usgs.gov