Conowingo Dam Above 90 Percent Capacity For Sediment Storage plus 2 more

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Title: USGS Newsroom

Conowingo Dam Above 90 Percent Capacity For Sediment Storage plus 2 more

Link to USGS Newsroom

Conowingo Dam Above 90 Percent Capacity For Sediment Storage

Posted: 18 Feb 2015 06:28 AM PST

Summary: The Conowingo Dam on the Susquehanna River is at about 92 percent capacity for sediment storage according to new U.S. Geological Survey research

Contact Information:

Michael Langland ( Phone: 717-730-6953 ); Hannah Hamilton ( Phone: 703-648-4356 );




The full report is available online

The Conowingo Dam on the Susquehanna River is at about 92 percent capacity for sediment storage according to new U.S. Geological Survey research.

Since the dam’s construction in 1929, sediment and nutrients have been building up behind it, being released periodically downriver and into the Chesapeake Bay, especially during high flow events.

“Storage capacity in Conowingo Reservoir continues to decrease, and ultimately that means more nutrients and sediment will flow into the Bay,” says Mike Langland, a USGS scientist and author of the study. “Understanding the sediments and nutrients flowing into the Bay from the Susquehanna River is critical to monitoring and managing the health of the Bay.”

Previous research has shown that having excess nutrients in the Bay depletes the water of oxygen needed to maintain healthy populations of fish, crabs, and oysters.  Additionally, the nutrients, along with sediment, cloud the water, disturbing the habitat of underwater plants crucial for aquatic life and waterfowl.

At full sediment-storage capacity, the Conowingo Reservoir will be about one-half filled with sediment, with the remainder--about 49 billion gallons--flowing water.  That amount of sediment could fill approximately 265,000 rail cars, which if lined up would stretch more than 4,000 miles.

The Susquehanna River is the largest tributary to Chesapeake Bay and transports about half of the total freshwater input to the Bay, along with substantial amounts of sediment, nitrogen and phosphorus.

Measuring the capacity of the dam to hold sediments and nutrients contributes to an improved understanding of factors that influence the health of the Chesapeake Bay.

Three hydroelectric dams and their associated reservoirs on the lower Susquehanna River have been impacting sediment and nutrient transport since construction in the early 1900’s. Previous USGS studies have shown the two upstream reservoirs have reached their sediment storage capacity and the most downstream dam and reservoir, the Conowingo, was also losing its ability to trap nutrients and sediment from reaching the Chesapeake Bay. A 2012 USGS report revealed that, even though the Conowingo reservoir had not yet reached its maximum storage capacity, it had begun to lose its phosphorus and sediment-trapping ability, with increasing amounts going into the Bay.

Due to the concerns about increasing nutrient and sediments loads flowing into the Bay, the U.S. Army Corps of Engineers, working with several partners, will soon be releasing ,the Lower Susquehanna River Watershed Assessment. The study suggests several sediment-management options for the reservoirs on the Lower Susquehanna River and indicated additional monitoring and research are needed to support management decisions.

The long-term analysis (1900-2012) conducted for this new USGS study reported here revealed how past practices affected sediment transport in the Susquehanna River Basin.

The USGS study, in addition to providing the current estimate of sediment capacity also provides a longer-term (100 years) analysis of sediment flowing into the reservoirs.

Sediment loads transported over the past 100 years in the Susquehanna River into the reservoirs have decreased from 8.7 million tons per year in the early part of the 20th century to the current level of about 3.5 million tons. The declines of sediment into the reservoirs since the 1950s are most likely related to introduction of soil conservation practices, land reverting back to forest, and better management of stockpiled coal piles.

Since construction of Conowingo Dam was completed in 1929, an average 70 percent of the transported sediment reaching the upper Chesapeake Bay is from the Susquehanna watershed. The additional 30 percent of the sediment is being scoured, or removed from sediment deposited in the reservoirs.

From 1929 through 2012, approximately 470 million tons of sediment was transported down the Susquehanna River into the reservoir system.  Of that number, approximately 290 million tons were trapped behind dams in the reservoirs, and approximately 180 million tons were transported to Chesapeake Bay. The reservoirs are continuously losing their ability to trap sediment and more is flowing into the Bay.

Information from this report and new partner studies will be used by the U.S. Environmental Protection Agency Chesapeake Bay Program and the state partners in considering options to reduce nutrient and sediment loads to help meet the requirements of the Chesapeake Bay Total Maximum Daily Load.

The study, Sediment Transport and Capacity Change in Three Reservoirs, Lower Susquehanna River Basin, Pennsylvania and Maryland, 1900–2012 Open-File Report 2014-1235 is available online.

Additional information on USGS Susquehanna results and Chesapeake Studies can be found online.

Show Me New Data for Show-Me State Maps

Posted: 18 Feb 2015 05:30 AM PST

Summary: Newly released US Topo maps for Missouri now feature selected trails and other substantial updates. The data for the trails is provided to the USGS through a nation-wide “crowdsourcing” project managed by the International Mountain Biking Association (IMBA)

Contact Information:

Mark Newell, APR ( Phone: 573-308-3850 ); Larry Moore ( Phone: 303-202-4019 );




Newly released US Topo maps for Missouri now feature selected trails and other substantial updates. The data for the trails is provided to the USGS through a nation-wide “crowdsourcing” project managed by the International Mountain Biking Association (IMBA). Several of the 1,196 new US Topo quadrangles for the state now display public trails along with additional improved data layers such as public land survey information, map symbol redesign and new road source data.

"The US Topo maps are widely used and appreciated by many state and local agencies," said Shelley Silch, The National Map liaison for Missouri and Illinois. "The addition of numerous trials to the new state US Topo quadrangles is a great advancement, as Missouri has been named the 'best trails state" by American Trails." 

For Missouri residents and visitors who want to explore the rolling Ozark landscape on a bicycle seat or by hiking, the new trail features on the US Topo maps will come in handy. During the past two years the IMBA, in a partnership with the MTB Project, has been building a detailed national database of mountain bike trails. This activity allows local IMBA chapters, IMBA members, and the public to provide trail data and descriptions through their website.  MTB Project and IMBA then verify the quality of the trail data provided, ensure accuracy and confirm the trail is legal.  This unique crowdsourcing venture has increased the availability of trail data available through The National Map mobile and web apps, and the revised US Topo maps.

Another important addition to the new Missouri US Topo maps is the inclusion of Public Land Survey System data. PLSS is a way of subdividing and describing land in the US. All lands in the public domain are subject to subdivision by this rectangular system of surveys, which is regulated by the U.S. Department of the Interior.

These new maps replace the first edition US Topo maps for Missouri and are available for free download from The National Map, the USGS Map Locator & Downloader website , or several other USGS applications.

To compare change over time, scans of legacy USGS topo maps, some dating back to the late 1800s, can be downloaded from the USGS Historical Topographic Map Collection

For more information on US Topo maps: http://nationalmap.gov/ustopo/

caption below caption below caption below
Updated 2015 version of the Weldon Spring, Missouri quadrangle with orthoimage turned on. (1:24,000 scale) (high resolution image 2.5 MB) Vintage 1903 quadrangle covering the O’Fallon, Missouri area from the USGS Historic Topographic Map Collection. 1:25,000 scale (high resolution image 3.3 MB) Updated 2015 version of Weldon Spring quadrangle with orthoimage turned off to better see the trail network. (1:24,000 scale) (high resolution image 1.8 MB)

Largest Dam Removal in U.S. History Scientifically Characterized

Posted: 17 Feb 2015 08:00 AM PST

Summary: The effects of dam removal are better known as a result of several new studies released this week by government, tribal and university researchers. The scientists worked together to characterize the effects of the largest dam removal project in U.S. history occurring on the Elwha River of Washington State

Contact Information:

Jonathan Warrick ( Phone: 831-460-7569 ); Paul Laustsen ( Phone: 650-329-4046 );




Aerial photos of the Elwha River mouth before and during dam removal. Photos show (A) the river mouth wetlands before dam removal, (B) the turbid coastal plume that occurred during much of the dam removal project, and (C) the expansion of the river mouth delta by sediment deposition. Photos provided by Ian Miller of Washington Sea Grant, Jonathan Felis of USGS, and Neal and Linda Chism of LightHawk.
Aerial photos of the Elwha River mouth before and during dam removal. Photos show (A) the river mouth wetlands before dam removal, (B) the turbid coastal plume that occurred during much of the dam removal project, and (C) the expansion of the river mouth delta by sediment deposition. Photos provided by Ian Miller of Washington Sea Grant, Jonathan Felis of USGS, and Neal and Linda Chism of LightHawk. (High resolution image)

SEATTLE — The effects of dam removal are better known as a result of several new studies released this week by government, tribal and university researchers. The scientists worked together to characterize the effects of the largest dam removal project in U.S. history occurring on the Elwha River of Washington State. New findings suggest that dam removal can change landscape features of river and coasts, which have ecological implications downstream of former dam sites.

“These studies not only give us a better understanding of the effects of dam removal, but show the importance of collaborative science across disciplines and institutions,” said Suzette Kimball, acting director of the U.S. Geological Survey.

Five peer-reviewed papers, with authors from the U.S. Geological Survey, Reclamation, National Park Service, Washington Sea Grant, NOAA Fisheries, the Lower Elwha Klallam Tribe, and the University of Washington, provide detailed observations and insights about the changes in the river’s landforms, waters and coastal zone during the first two years of dam removal. During this time, massive amounts of sediment were eroded from the drained reservoirs and transported downstream through the river and to the coast. 

One finding that intrigued scientists was how efficiently the river eroded and moved sediment from the former reservoirs; over a third of the 27 million cubic yards of reservoir sediment, equivalent to about 3000 Olympic swimming pools filled with sediment, was eroded into the river during the first two years even though the river’s water discharge and peak flows were moderate compared to historical gaging records. 

This sediment release altered the river’s clarity and reshaped the river channel while adding new habitats in the river and at the coast. In fact, the vast majority of the new sediment was discharged into the coastal waters of the Strait of Juan de Fuca, where the river mouth delta expanded seaward by hundreds of feet. 

“The expansion of the river mouth delta is very exciting, because we are seeing the rebuilding of an estuary and coast that were rapidly eroding prior to dam removal,” said USGS research scientist and lead author of the synthesis paper, Dr. Jonathan Warrick. 

Although the primary goal of the dam removal project is to reintroduce spawning salmon runs to the pristine upper reaches of the Elwha River within Olympic National Park, the new studies suggest that dam removal can also have ecological implications downstream of the former dam sites. These implications include a renewal of the sand, gravel and wood supplies to the river and to the coast, restoring critical processes for maintaining salmon habitat to river, estuarine and coastal ecosystems.

“These changes to sediment and wood supplies are important to understand because they affect the river channel form, and the channel form provides important habitat to numerous species of the region,” stated USGS research scientist and river study lead author, Dr. Amy East.

The final stages of dam removal occurred during the summer of 2014. Some sediment erosion from the former reservoirs will likely continue. The Elwha Project and research teams are continuing to monitor how quickly the river returns to its long-term restored condition.

“We look forward to seeing when the sediment supplies approach background levels,” said Reclamation engineer and co-author, Jennifer Bountry, “because this will help us understand the length of time that dam removal effects will occur.” 

The five new papers can be found in Elsevier’s peer-reviewed journal, Geomorphology, and they focus on the following topics of the large-scale dam removal on the Elwha River, Washington (web-based publication links using digital object identifiers, doi, are provided in parentheses): 


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