The Science of Stream Buffers

Lake George Stream Corridor Management Stakeholder Meeting

May 28, 2008

About the Center forAbout the Center forWatershedWatershed ProtectionProtection

• Non-profit 501(c)3, non-advocacy organizationNon-profit 501(c)3, non-advocacy organization• Work with watershed groups, local, state, and Work with watershed groups, local, state, and

federal governmentsfederal governments• Provide tools communities need to protect Provide tools communities need to protect

streams, lakes, and riversstreams, lakes, and rivers• 20 staff in Ellicott City, MD and satellite Offices20 staff in Ellicott City, MD and satellite Offices

www.cwp.orgwww.cwp.orgwww.stormwatercenter.net www.stormwatercenter.net

Small Streams Small Streams Small Streams Small Streams

• 11stst and 2 and 2ndnd order 73% of order 73% of our stream miles (Leopold, our stream miles (Leopold, 1964)1964)

• Drain the majority of the Drain the majority of the landscape landscape

• Connected to a high Connected to a high percentage of our wetlandspercentage of our wetlands

• 11stst and 2 and 2ndnd order 73% of order 73% of our stream miles (Leopold, our stream miles (Leopold, 1964)1964)

• Drain the majority of the Drain the majority of the landscape landscape

• Connected to a high Connected to a high percentage of our wetlandspercentage of our wetlands

• Effective at processing Effective at processing nutrients nutrients

• Most frequently Most frequently disturbed during the disturbed during the development processdevelopment process

• Effective at processing Effective at processing nutrients nutrients

• Most frequently Most frequently disturbed during the disturbed during the development processdevelopment process

Juniper Inlet, FL: NOAA 1997

• Organic matter

• Shading

• Nutrient and sediment retention

• Bank stability

• Habitat for wildlife

Forested Stream ServicesForested Stream Services

Forested Streams

•Fallen leaves are the base of the food chain in small streams, and provide as much as 75% of the energy input to the food chain

•Woody debris enhances organic matter and nutrient retention, dissipates energy and reduces downcutting (Meyer and Wallace, 2001)

•An average nutrient molecule travels less than 20m downstream before being removed in a high quality small shallow stream (Webster et al, 2002)

Basics of Stream Buffers

• Stream buffers are more than a line on a map

• It is more than a setback• The floodplain is the core of the buffer• Management is just as important as width• Should be continuous

– Gaps can introduce additional surface flow

Water quickly runs off a shoreline cleared of natural vegetation, washing nutrients and pesticides into the water. A natural shoreline holds rainfall, which soaks into the soil; less water, soil and chemicals run into the lake or river. Shoreline and aquatic plants anchor shoreline areas, helping to protect them from erosion due to runoff and waves (Source:MN DNR)

Source: Minnesota Department of Natural Resources

Benefits of Stream Buffers

Environmental Economic / Community

How many can you name?

Environmental Benefits• Provides room for streams to safely adjust laterally over time• Provides additional streambank erosion protection• Provides distance from impervious cover• Helps prevent steep slope erosion and disturbance• Helps keep stream temperatures down• Pollutant removal

Sediment Phosphorus and nitrogen Bacteria

Source: Wenger, 1999

Temperature

• Many coldwater fish species have limited temperature range tolerance (e.g., trout)

• Stream warming from is caused by a variety of factors:– Loss of riparian cover (air temp in headwater

streams)– Impervious surfaces– Stormwater ponds

• 60% riparian forest cover retains temperature• 80% riparian forest lowers temperature

Sediment

• Sources - stream bank erosion- poor forestry, agriculture or mining practices- construction sites

• Impacts - reduced habitat for macroinvertebrates and fish- increased pollutants attached to sediment- increased cost to remove and dispose of sediment- potential for direct fish kill with high concentrations of fine, deposited sediment

Phosphorus

• Sources- generally accumulates attached to sediment particles- application of fertilizers on lawns and ag fields- animal waste and septic

• Impacts-Eutrophication of lakes-Shift in biota of stream systems

Economic/Community Benefits• Reduce public investment in stormwater management, flood control, and pollutant removal• Increase property values• Provide habitat for wildlife• Reduce watershed impervious cover• Help minimize flooding and associated property damage• Reduce time and expense of land maintenance, as compared to managed turf• Reduce small drainage problems and complaints

Stream Buffer Design

• Preferred widths– Sediment removal– Phosphorus/Nitrogen removal

• Special resource/protection areas

• Three-zone buffer design

• Allowable uses

Modified from: Emmons & Olivier Resources, 2001

Critical Buffer Widths

(EOR, 2001)

Buffer Widths and Pollutant Removal

Source: Wenger, 1999

Pollutant Removal Rate Necessary Width*

Sediment (as TSS)

66-93% 90 ft

78% 70 ft

94% 190 ft

Phosphorus (as TP)

See above

84% 164 ft

81% 92 ft

Temp N/A 30 ft of forest* Depends on slope, soils, infiltration rates, etc.

Special Resource/Protection Areas

• Base width should be expanded to include:– Ultimate 100 year floodplain– Very steep slopes greater than 25%

• Wetlands, critical habitats and forest conservation areas should have larger buffers

Three-Zone Buffer Design

• Each zone has different function, width, vegetative target, and management:

– Streamside zone: 25 feet of undisturbed forest cover

– Middle zone: 50 feet or more ofmanaged forest

– Outer zone: 25 feet of grass or forest setback from structures

Stream Buffer Crossings

• To minimize fish blockages, all crossings should follow these guidelines: – Width: minimum right of way needed for access– Angle: perpendicular to stream– Frequency: no more than one crossing/1000 feet– Depth: utilities three feet below streambed– Capacity: convey 100 year storm– Culverts: bottomless, slab, arch or box designs

preferred

Buffer Crossings

Buffer xing photo

Stream xing photo Minimize clearing required to create a buffer crossing.

Riparian Buffer Management

Riparian Buffer Management

Recommended Reading

• Emmons and Olivier Resources. Benefits of Wetland Buffers: A Study of Functions, Values and Sizes. http://www.minnehahacreek.org/documents/MCWD_Buffer_Study.pdf

• Meyer, J.L. and J.B. Wallace. 2001. Lost linkages and lotic ecology: rediscovering small streams. http://cwt33.ecology.uga.edu/publications/1444.pdf

• Sweeney, B.W., T.L. Bott, J.K. Jackson, L.A. Kaplan, J.D. Newbold, L.J. Standley, W.C. Hession, and R.J. Horwitz. 2004. Riparian Deforestation, Stream Narrowing, and Loss of Stream Ecosystem Services. Proceedings of the National Academy of Sciences 101(39):14132-14137. http://www.stroudcenter.org/about/pdfs/bs_PNAS092804.pdf

• Wenger, S. 1999. A review of the scientific literature on riparian buffer width, extent, and vegetation. Publication of the Office of Public Service and Outreach, Institute of Ecology, University of Georgia. 58pp.