SLIDE 1
Wa Water Quality Buffers for Wa Waters an and Wetlan lands 2008 - - PowerPoint PPT Presentation
Wa Water Quality Buffers for Wa Waters an and Wetlan lands 2008 - - PowerPoint PPT Presentation
Wa Water Quality Buffers for Wa Waters an and Wetlan lands 2008 Noreaster: Indian River Bay Progress Towards Pollution Reduction Goals for the Inland Bays Phosphorus Nitrogen (lbs. per day) (lbs. per day) 1,471 2,427 93 Achieved
SLIDE 2
SLIDE 3
SLIDE 4
SLIDE 5
Progress Towards Pollution Reduction Goals for the Inland Bays
1,471 2,427
Nitrogen
(lbs. per day)
Achieved Remaining 93
Phosphorus
(lbs. per day)
Achieved
SLIDE 6
SLIDE 7
SLIDE 8
SLIDE 9
SLIDE 10
SLIDE 11
SLIDE 12
SLIDE 13
Water Quality Buffers are…
natural areas between development and wetlands or waterbodies; they are managed for the primary purposes of: 1.sustainable removal of pollutants entering wetlands or waterbodies, 2.to protect wetlands or waterbodies against encroachment and physical alterations, and 3.to allow wetlands or waterbodies to maximize their own natural capacities to reduce pollution.
SLIDE 14
Forested Buffer
~ 200’
SLIDE 15
Buffer Considerations
- Extent
- Vegetation
- Field Ditches
- Views
- Approval and Enforcement
- Width
SLIDE 16
Headwaters(small streams) make up ~75% of total waterway length
Headwaters are more efficient at removing pollution than larger streams
SLIDE 17
SLIDE 18
SLIDE 19
Turf Forest
Vegetation Type
Turf vs. Forest
- Forested buffers remove 36%
more nitrogen on average than grassed buffers
- Forested buffers take up 11 – 37
lbs of nitrogen and 2 – 5 lbs of phosphorus per acre per year into wood
- Soil organic matter is over twice as
high in forested buffers
- Forested buffers improve instream
processing of nutrients
- Forested buffers support wildlife
habitat and don’t contribute pollution
SLIDE 20
SLIDE 21
SLIDE 22
Effect of Buffer Width on Nitrogen Removal from 17 Atlantic Coastal Plain Riparian Buffers
Buffer Width (ft.)
100 200 300
% Nitrogen Removal
- 60
- 40
- 20
20 40 60 80 100 120 140
y=-7915.6564+((8015.6442x)/(0.1813+x))
Rsqr = 0.67 p = 0.0005
- --- = 95% Confidence Int.
Effect of Buffer Width on Nitrogen Removal for 17 Atlantic Coastal Plain Riparian Buffers
SLIDE 23
BAY MARSH UPLAND
SLIDE 24
BAY MARSH UPLAND
SLIDE 25
SLIDE 26
SLIDE 27
BAY MARSH UPLAND DEVELOPMENT
SLIDE 28
BAY MARSH UPLAND DEVELOPMENT
SLIDE 29
BAY MARSH UPLAND DEVELOPMENT
SLIDE 30
BAY MARSH UPLAND DEVELOPMENT SHORELINE ARMOR
SLIDE 31
BAY MARSH UPLAND DEVELOPMENT SHORELINE ARMOR
SLIDE 32
BAY MARSH UPLAND DEVELOPMENT SHORELINE ARMOR
SLIDE 33
BAY MARSH UPLAND DEVELOPMENT
SLIDE 34
Mouth of Guinea Creek Bay Shoreline Upland/Wetland Boundary Bay Shoreline Upland/Wetland Boundary
SLIDE 35
Slope of Adjacent Upland Indian River Bay Rehoboth Bay Gradual (<0.08 rise/run) 5.25 ft/yr 6.07 ft/yr Steep (>0.09 rise/run) 1.44 ft/yr 0.82 ft/yr
Rates of tidal wetland migration
derived from metric mapping analysis 1926-1989
SLIDE 36
Fi Field Ditches
SLIDE 37
Approval and Enforcement
SLIDE 38
SLIDE 39
SLIDE 40
SLIDE 41
SLIDE 42
New Castle Co., DE Kent Co., DE Sussex Co., DE New Jersey Maryland Critical Areas CIB Adequate CIB Optimum Tidal Wetlands & Waters 100 ft. 100 ft. 50 ft. 300 ft. 200 ft. 80-300 ft. 150-500 ft. Nontidal Wetlands 50 ft. 25 ft. 0 ft. 0 – 150 ft. 25 ft. 50 100 Headwaters 100 ft. 50 ft. 0 ft. 300 ft. 100 ft. 35 - 80 35 -150 Larger/Perennial Waterways 100 ft. or 50
- ft. from
floodplain 100 ft. 0 – 50 ft. 300 ft. 100 ft. 80 150 Vegetation Type Natural/ Forest Natural /Forest Natural/ Forest Existing Vegetation or Natural /Forest Natural /Forest Natural /Forest Natural /Forest Vegetation Preservation Existing native vegetation Existing natural buffers Existing natural buffers Existing vegetation Existing natural vegetation Existing native vegetation Existing native vegetation Buffer Mgmt. Plan No No No Yes Yes Yes Yes
Buffer Ordinance Comparison
SLIDE 43
Analysis of Recommendations Applied to Developments
- 11 randomly selected PLUS applications:
’04-’06.
l Separated into large
(>75th percentile) & small projects (<50th percentile) and by watershed region
l Estimated %
developable acreage as buffer by waterbody type and buffer alternative
Well Drained Region
Poorly Drained Region
SLIDE 44
Results
- On average, buffers were within range of current County
- pen space requirements
- Adequate = 13.8% of developable acreage
- Optimum = 33.2% of developable acreage
- Sites with tidal wetlands by low lying uplands had very
large areas as buffers
- Encourage filling or integration into stormwater controls
those ditches unnecessary for drainage.
- Smaller buffer widths should be afforded (>35’) on shallow
ditches (< 3 ft deep) to allow buffering of other features
SLIDE 45
Site Characteristics Adequate Alternative Optimum Alternative
Applying Recommendations: Bethany Woods
Acreage 12 Developable Ac. 9 % Dev. Ac. in Buffer (Adequate) 61 % Dev. Ac. in Buffer (Optimum) 89
Tidal Nontidal Wtlnds Nontidal Waterway Nontidal Wetland Tidal Wetlands Buffer Types Waterbody Type Development Major Ditches
SLIDE 46
Site Characteristics Adequate Alternative Optimum Alternative Acreage 314 Developable Ac. 309 % Dev. Ac. in Buffer (Adequate) 1.8 % Dev. Ac. in Buffer (Optimum) 3.7
Tidal Nontidal Wtlnds Nontidal Waterway Nontidal Wetland Tidal Wetlands Buffer Types Waterbody Type Development
Applying Recommendations: Bridlewood
SLIDE 47
Indian River Bay Rehoboth Bay Upland Buffer Width Gradual Slope Steep Slope Gradual Slope Steep Slope 50’ 10 35 8 61 75’ 14 52 12 91 100’ 19 69 17 122 200’ 38 139 33 244 300’ 57 208 49 366 400’ 76 278 66 488 500’ 95 347 82 610
Years buffers of different widths are estimated to provide protection to tidal wetlands
derived from metric mapping analysis 1926-1989