NOAA, Partners Predict an Average 'Dead Zone' for Gulf of Mexico; Slightly Above­ Average Hypoxia in Chesapeake Bay plus 1 more

[USGS Newsroom <oc_web@xxxxxxxx>]

Title: USGS Newsroom

NOAA, Partners Predict an Average 'Dead Zone' for Gulf of Mexico; Slightly Above­ Average Hypoxia in Chesapeake Bay plus 1 more

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NOAA, Partners Predict an Average 'Dead Zone' for Gulf of Mexico; Slightly Above­ Average Hypoxia in Chesapeake Bay

Posted: 24 Jun 2014 11:05 AM PDT

Summary: Scientists are expecting an average, but still large, hypoxic or "dead zone" in the Gulf of Mexico this year, and slightly above-average hypoxia in the Chesapeake Bay

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Contact Information:

Ben Sherman ( Phone: 202-253-5256 ); Michael Woodside ( Phone: 615-837-4706 ); Ethan Alpern ( Phone: 703-648-4406 );

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Scientists are expecting an average, but still large, hypoxic or "dead zone" in the Gulf of Mexico this year, and slightly above-average hypoxia in the Chesapeake Bay.  

NOAA-supported modeling is forecasting this year's Gulf of Mexico hypoxic zone to cover an area ranging from about 4,633 to 5,708 square miles (12,000 to 14,785 square kilometers) or about the size of the state of Connecticut.

While close to averages since the late 1990s, these hypoxic zones are many times larger than what research has shown them to be prior to the significant human influences that greatly expanded their sizes and effects.  

The Gulf of Mexico prediction is based on models developed by NOAA-sponsored modeling teams and individual researchers at the University of Michigan, Louisiana State University, Louisiana Universities Marine Consortium, Virginia Institute of Marine Sciences/College of William and Mary, Texas A&M University, and the U.S. Geological Survey,  and relies on nutrient loading estimates from the USGS. The models also account for the influence of variable weather and oceanographic conditions, and predict that these can affect the dead zone area by as much as 38 percent.  

A second NOAA-funded forecast, for the Chesapeake Bay, predicts a slightly larger than average dead zone in the nation's largest estuary. The forecast predicts a mid-summer low-oxygen hypoxic zone of 1.97 cubic miles, an early-summer oxygen-free anoxic zone of 0.51 cubic miles, with the late-summer oxygen-free anoxic area predicted to be 0.32 cubic miles. Because of the shallow nature of large areas of the estuary the focus is on water volume or cubic miles, instead of square mileage as used in the Gulf.

The Chesapeake Bay prediction is based on models developed by NOAA-sponsored researchers at the University of Maryland Center for Environmental Science, University of Michigan, and again relies on nutrient loading estimates from USGS.

The dead zone in the Gulf of Mexico affects nationally important commercial and recreational fisheries and threatens the region's economy. The Chesapeake Bay dead zones, which have been highly variable in recent years, threaten a multi-year effort to restore the water and habitat quality to enhance its production of crabs, oysters, and other important fisheries.

Hypoxic (very low oxygen) and anoxic (no oxygen) zones are caused by excessive nutrient pollution, primarily from human activities such as agriculture and wastewater, which results in insufficient oxygen to support most marine life and habitats in near-bottom waters. Aspects of weather, including wind speed, wind direction, precipitation and temperature, also affect the size of dead zones.

"We are making progress at reducing the pollution in our nation's waters that leads to 'dead zones,' but there is more work to be done," said Kathryn D. Sullivan, Ph.D., under secretary of commerce for oceans and atmosphere and NOAA administrator. "These ecological forecasts are good examples of the critical environmental intelligence products and tools that NOAA provides to interagency management bodies such as the Chesapeake Bay Program and Gulf Hypoxia Task Force.  With this information, we can work collectively on ways to reduce pollution and protect our marine environments for future generations."

Later this year, researchers will measure oxygen levels in both bodies of water. The confirmed size of the 2014 Gulf hypoxic zone will be released in late July or early August, following a mid-July monitoring survey led by the Louisiana Universities Marine Consortium. The final measurement in the Chesapeake will come in October following surveys by the Chesapeake Bay Program's partners from the Maryland Department of Natural Resources and the Virginia Department of Environmental Quality.

USGS nutrient-loading estimates for the Mississippi River and Chesapeake Bay are used in the hypoxia forecasts for the Gulf and Chesapeake Bay. The Chesapeake data are funded with a cooperative agreement between USGS and the Maryland Department of Natural Resources. USGS also operates more than 65 real-time nitrate sensors in these two watersheds to track how nutrient conditions are changing over time.

For the Gulf of Mexico USGS estimates that 101,000 metric tons of nitrate flowed down the Mississippi River into the northern gulf in May 2014, which is less than the 182,000 metric tons in last May when stream flows were above average. In the Chesapeake Bay USGS estimates that 44,000 metric tons of nitrogen entered the bay from the Susquehanna and Potomac rivers between January and May of 2014, which is higher than the 36,600 metric tons delivered to the Bay during the same period in 2013.

"The USGS continues to conduct long-term nutrient monitoring and modeling" said William Werkheiser, USGS associate director for water. "This effort is key to tracking how nutrient conditions are changing in response to floods and droughts and nutrient management actions."

The research programs supporting this work are authorized under the Harmful Algal Bloom and Hypoxia Research and Control Act, known as HABHRCA, which was recently amended and reauthorized earlier this month through 2018.

Human Activities Increase Salt Content in Many of the Nation's Streams

Posted: 16 Jun 2014 06:18 AM PDT

Summary: Concentrations of dissolved solids, a measure of the salt content in water, are elevated in many of the Nations streams as a result of human activities, according to a new USGS study

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Contact Information:

Ethan Alpern ( Phone: 703-648-4406 ); David Anning ( Phone: 928-556-7139 );

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Concentrations of dissolved solids, a measure of the salt content in water, are elevated in many of the Nations streams as a result of human activities, according to a new USGS study. Excessive dissolved-solids concentrations in water can have adverse effects on the environment and on agricultural, domestic, municipal, and industrial water users.

Results from this study provide a nation-wide picture of where dissolved-solids concentrations are likely to be of concern, as well as the sources leading to such conditions.

“This study provides the most comprehensive national-scale assessment to date of dissolved solids in our streams,” said William Werkheiser, USGS Associate Director for Water. “For years we have known that activities, such as road de-icing, irrigation, and other activities in urban and agricultural lands increase the dissolved solids concentrations above natural levels caused by rock weathering, and now we have improved science-based information on the primary sources of dissolved-solids in the nation’s streams.”

The highest concentrations are found in streams in an area that extends from west Texas to North Dakota. Widespread occurrences of moderate concentrations are found in streams extending in an arc from eastern Texas to northern Minnesota to eastern Ohio. Low concentrations are found in many states along the Atlantic coast and in the Pacific Northwest.

The total amount of dissolved solids delivered to all of the Nation’s streams is about 270 million metric tons annually, of which about 71% comes from weathering of rocks and soil, 14% comes from application of road deicers, 10% comes from activities on agricultural lands, and 5% comes from activities on urban lands.

All water naturally contains dissolved solids as a result of weathering processes in rocks and soils. Some amount of dissolved solids is necessary for agricultural, domestic, and industrial water uses and for plant and animal growth, and many of the major ions are essential to life and provide vital nutritional functions. Elevated concentrations, however, can cause environmental and economic damages. For instance, estimated damages related to excess salinity in the Colorado River Basin exceed $330 million annually.

“This study applied statistical modeling to understand the sources and transport processes leading to dissolved-solids concentrations observed in field measurements at over 2,500 water-quality monitoring sites across the Nation,” said David Anning, USGS lead scientist for the study. “This new information was then used to estimate contributions from different dissolved-solids sources and the resulting concentrations in unmonitored streams, thereby providing a complete assessment of the Nation’s streams.”

The study determined that in about 13 percent of the Nation’s streams, concentrations of dissolved solids likely exceed 500 mg/L, which is the U.S. Environmental Protection Agency’s secondary, non-enforceable drinking water standard. Many of these streams are found in a north-south oriented band stretching from west Texas to North Dakota.

While this standard provides a benchmark for evaluating predicted concentrations in the context of drinking-water supplies, it should be noted that it only applies to drinking water actually served to customers by water utilities.

An online, interactive decision support system provides easy access to the national-scale model describing how streams receive and transport dissolved solids from human sources and weathering of geologic materials. The decision support system can used to evaluate combinations of reduction scenarios that target one or multiple sources and see the change in the amount of dissolved solids transported downstream waters.

The dissolved-solids model was developed by the USGS National Water-Quality Assessment Program, which provides information about water-quality conditions and how natural features and human activities affect those conditions. Information on modeling applications, data, and documentation can be accessed online.