Wetlands and bioretention systems: Landscape filters in the Bay watershed

Andrew H. Baldwin baldwin@umd.eduDepartment of Environmental Science and Technology

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Brackish marsh

Red maple/skunk cabbage swamp

Pickerelweed

Saltmarsh mallow

M. Perry

G. Kearns

A. Young

R. Aguilar

White-footed mouse Bald eagle

Blue crab

Green sunfish

Fishing spider

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SOUTH RIVER

ANNAPOLIS

SEVERN RIVER

PA

TU

XE

N T

RIV

ER

CHESBAY

Wetlands lie between dry land and the Bay

NWI Wetlands Mapper

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SOUTH RIVER

ANNAPOLIS

SEVERN RIVER

PA

TU

XE

N T

RIV

ER

CHESBAY

They intercept runoff and groundwater

N2

gas

(nitr

ogen

rem

oval

)

Sediment and phosphorus burial

Strategic restoration and creation of wetlands for water quality improvement

Mitsch et al. 2001

Urban Stormwater Wetland

Stormwater wetland at the University of Maryland, College Park. Runoff from the parking lot enters the wetland from the left, flows in a roughly U-shaped counterclockwise pattern, and discharges via a riser a the top center of the wetland. Photo by A.H. Baldwin.

**

Surface Flow (SF) Wetland

Subsurface Flow(SSF) Wetland

Soil substrate over impermeable layer (clay, bentonite, liner)

Gravel substrate over impermeable layer

**

Constructed wetlands for wastewater treatment (e.g. dairy farm effluent)

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Bioretention systems

To stream

To groundwater

- Store and slowly release surface runoff to streams or groundwater (reduced flood peaks)- Filter out sediment- Remove sorbed pollutants (e.g. phosphorus and metals)

These are not wetlands!

PG County Bioretention Manual, 2009

Laurel Hospital Ivy Club Apartments

King’s Contrivance Greenbelt Plaza

Conclusions Wetlands and bioretention systems improve

Bay water quality “Kidneys of the landscape” Provide biodiversity, flood storage, and other

ecosystem services

Thank you!

K. Jensen

Supplemental slides