Transcript Belgrade Regional Conservation Alliance

Vegetated Riparian Buffers:
Developing Science-based
Ordinance Protection
Belgrade
Regional
Conservation
Alliance
Outline
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What do we mean by riparian buffers?
Values of buffers-what do they do?
How wide do they need to be?
How do they work?
What are characteristics of a good buffer?
Buffer ordinances- how do we protect
buffers?
• Summary and recommendations
What do we mean by Riparian
Buffers?
• Vegetated transition zones between upland and
aquatic ecosystems
– Provide wildlife habitat
– Provide nutrients and energy for aquatic systems
– Protect water quality
• Shading
• Nutrient uptake
• Pollutant removal
– Stabilize shorelines
– Provide flood control and protection
Riparian Buffer Cross-Section
Riparian Buffer
Plantings
Headwater Stream Buffers
How Wide Should a Buffer Be?
Buffers and Water Quality
• Settling of particulates
– Potential for resuspension
• Adsorption and ion exchange-surface
– plants, substrate, sediment, litter
• Plant uptake (temporary storage)
• Microbial biodegradation
• Denitrification
• Soil sequestration
• Predation and die off of pathogens
Characteristics of Runoff
• Groundwater flows
– Velocities very slow: 1-3 ft/day
– Pollutants dissolved
• Sheet flows
– Velocities moderate: 1-5 ft/min
– Pollutants dissolved and particulate
• Concentrated flows
– High velocity: in excess of 1 ft/sec
– Pollutants primarily particulate
The Impact of Development
on Storm Water Runoff
natural
conditions
The Impact of Development
on Storm Water Runoff
medium
density
development
Déjà Vu
“There are mountains in Attica, which can now keep
nothing but bees, but which were clothed, not so
very long ago, with fine trees producing timber
suitable for roofing the largest buildings….while the
country produced boundless pasture for cattle. The
annual supply of rainfall was not lost, as it is at
present, through being allowed to flow over a
denuded surface to the sea, but was received by
the earth, in all its abundance, into her bosom
where she stored it.”
Plato: Dialogue of Critias 360 B.C.E
Stormwater Runoff
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Fertilizers
Pesticides
Bacteria from pet and agricultural waste
Eroded soil
– Flowing water erodes even more soil
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Road salt
Oil and grease, antifreeze
Heavy metals
Grass clippings
(M)
From: Wenger (1999)
From: Wenger (1999)
From: Wenger (1999)
Phosphorous Release from Particulates vs.
Temperature
Ref: Karr, 1977
Characteristics of good buffers
• Dense vegetation to slow flows
– Multi layer: trees, shrubs, forbs
– No channels or shortcuts
• Native plants
• Developed root systems to encourage infiltration
and microbial rhizosphere communities
• Permeable soils with high organic content
• Grassy edges to encourage sheet flow
Transpiring
Recyclable
Energy
Efficient
Stormwater System
TREES
Role of Plants
• Production of organic matter-photosynthesis
• Shading and cooling (evapotranspiration)
• Organic matter decays to litter layer
– trickling filter, adsorption bed
– burial and diagenesis-organic carbon at depth
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Stabilization of sediments
Slow flows- enhance sedimentation
Epiphytic algae and bacteria
Oxidized rhizosphere
Evapotranspiration-driven transport
Bioturbation and bioirrigation
Deja Vu
The roots of the willows do not suffer the banks of the canals to be
destroyed; and the branches of the willows, nourished during their
passage through the thickness of the bank and then cut low, thicken
every year and make shoots continually, and so you have a bank that
has life and is of one substance.
-Leonardo Da Vinci (1452-1519)
Recommendations (Wenger, 1999)
• Option 1: 100 ft + 2 ft per 1% of slope
– Include all floodplain and adjacent wetlands
– Impervious areas and slopes over 25% excluded
– All perennial, intermittent, and ephemeral streams
• Option 2: 50 ft + 2 ft per 1% of slope
– All perennial, 2nd order intermittent streams
• Option 3: Fixed buffer width of 100 ft
– All perennial, 2nd order intermittent streams
Protection of Riparian Buffers
• Regulations and ordinances must be
scientifically defensible
• Must be easily understandable and
implementable
• Must be enforceable
• Must take into account local conditions
Protective Regulations:
Shoreland Zoning Act
75 ft vegetated
buffer from
high water line
Up to 40 %
thinning over
10 yr period
Shoreland Zoning
Designed for reducing the impacts of development
Retains the natural forest floor
NJ Stream Encroachment Rules
• Riparian zone regulated:
– 300 ft for Category I waters
– 150 ft for trout waters and T+E waters
including tributaries 1 mi upstream and for
acid-producing soils
– 50 ft all other waters (USGS Topo or Soil
Survey Maps)
• Permit by rule for agriculture
Effective Buffer Ordinances
• Provide guidelines for buffer creation and
maintenance and should require:
– Justification for buffer protection
– Buffer boundaries to be clearly marked on
local planning maps
– Maintenance language that restricts
vegetation and soil disturbance
– Tables that illustrate buffer width adjustment
by percent slope and type of stream
– Direction on allowable uses and public
education
Model Ordinances
• EPA web site:
• www.epa.gov/owow/nps/ordinance/buffers.htm
– Contains ten different model ordinances with
language for special circumstances (erodible soils
etc.)
• Center for Watershed Protection:
• www.cwp.org/Resource_Library/Model_Ordinances/index.htm
– Contains post-construction ordinances, wetlands
protection ordinances
Typical Ordinance Content
1: Background
Why buffers important
2: Intent
Purpose of the ordinance
3: Definitions
4: Applications
Development, mining, timber, agriculture
5: Plan Requirements
Wetlands, slopes, soils, etc
6: Design Standards for Forest Buffers
How wide, slopes, hazards, zones, etc
Typical Ordinance Content (Cont.)
7: Buffer Management and Maintenance
Clearing, roads, bridges, paths, stormwater, invasive species, etc
8: Enforcement
Who, penalties, etc
9: Waivers/Variances
Grandfathering, variance procedures
10: Conflict with other Regulations
Most stringent shall govern
References
Summary and Recommendations
• Buffers perform critical functions for Water
Quality
• Existing regulations (Shoreland zoning)
provide some protection
• Protective ordinances can provide
additional protective
• Must be based on science and local
conditions to be effective and defensible
References
• Mayer et al. 2005. Riparian Buffer Width, Vegetative
Cover, and Nitrogen Removal Efectiveness- A Review of
Current Science and Regulations. USEPA 600/R-05/118
• Wenger, 1999. A review of the scientific literature on
riparian buffer width, extent, and vegetation. U. GA.
March, 1999.
• Karr, 1977. Impact of nearstream vegetation and stream
morphology on water quality and stream biota. USEPA
600/3-77-097
More References
Questions?
Belgrade Regional Conservation Alliance
P.O. Box 250
Belgrade Lakes, ME 04918
(207) 495-6039
http://www.belgradelakes.org
[email protected]