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Connectivity Best for Created Wetlands



Connectivity Best for Created Wetlands

New research by the U.S. Geological Survey has found that many wetlands created for habitat do very little to improve water quality problems in streams and rivers. Collectively, these wetland design practices represent a missed opportunity to improve the general ecological health of watersheds and wetland ecosystems. 

“Wetlands provide many significant benefits for ecosystems and for people,” said Jerad Bales, acting USGS Associate Director for Water. “While wetlands provide important and unique habitat for great numbers of plants and animals, they also are valuable to humans for flood protection, water quality improvement, and recreation, to name just a few of their benefits. Understanding and improving the contributions of created wetlands to the larger goal of healthy watersheds is a valuable scientific insight.” 

Wetlands are often created for mitigating impacts to wetlands elsewhere. “Restored wetland,” “mitigation wetland,” and “replacement wetland” are similar terms for created wetlands.  Created wetlands typically range from several acres to tens of acres in size and are usually built with berms to regulate water levels precisely.  

These wetland creation practices prevent the exchange of water with adjacent streams and rivers. This lack of hydrologic connectivity to streams then has the consequence of limiting inputs of pollutants (sediment, nitrogen, and phosphorus) to both created and natural wetlands where the detrimental effects of these pollutants could be mitigated. In the watershed of the Chesapeake Bay, reducing sediment, nitrogen, and phosphorus pollution is a focus of large efforts to restore rivers and the Bay. 

USGS ecologist Greg Noe observed, “Unless a wetland can intercept the large amounts of pollutants in streams and rivers, it doesn’t have a chance to remove any of the pollution.” 

Improving habitat for wildlife is one of many reasons for wetland creation and restoration. In some cases, this specific goal may be best managed by limiting nutrient and sediment inputs through limited stream hydrologic connectivity.  However, created wetlands may have poor quality soils which limit the development of these young wetlands and consequently lead to poor habitat.    

USGS scientists, working in collaboration with George Mason University, also found that increasing inputs of sediment, nitrogen, and phosphorus by increasing connectivity to streams stimulated nutrient availability. It is through this process that increased hydrologic connectivity can create more mature wetland systems faster. 

“If you want to maximize the overall water quality benefits of wetland creation,” said Noe, “then design the wetland so that it exchanges water with a stream or river.” 

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USGS Newsroom



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Parameter Value Description
Magnitude mb The magnitude for the event.
Longitude ° East Decimal degrees longitude. Negative values for western longitudes.
Latitude ° North Decimal degrees latitude. Negative values for southern latitudes.
Depth km Depth of the event in kilometers.
Place Textual description of named geographic region near to the event. This may be a city name, or a Flinn-Engdahl Region name.
Time 1970-01-01 00:00:00 Time when the event occurred. UTC/GMT
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Timezone offset Timezone offset from UTC in minutes at the event epicenter.
Felt The total number of felt reports
CDI The maximum reported intensity for the event.
MMI The maximum estimated instrumental intensity for the event.
Alert Level The alert level from the PAGER earthquake impact scale. Green, Yellow, Orange or Red.
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Tsunami This flag is set to "1" for large events in oceanic regions and "0" otherwise. The existence or value of this flag does not indicate if a tsunami actually did or will exist.
SIG A number describing how significant the event is. Larger numbers indicate a more significant event.
Network The ID of a data contributor. Identifies the network considered to be the preferred source of information for this event.
Sources A comma-separated list of network contributors.
Number of Stations Used The total number of Number of seismic stations which reported P- and S-arrival times for this earthquake.
Horizontal Distance Horizontal distance from the epicenter to the nearest station (in degrees).
Root Mean Square sec The root-mean-square (RMS) travel time residual, in sec, using all weights.
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Event ID Id of event.
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