Takings vs. Givings:

Science and Policy in Riparian Setback Zoning

Stu SchwartzCenter for Urban Environmental Research and EducationUniversity of Maryland Baltimore County

Overview

Setbacks vs. Buffers

3 Generations of Riparian Science & Setback Zoning

Needs & Opportunities in Urban Riparian Science

Buffer Function + Zoning ≈ Riparian Setback

As a zoning instrument setbacks:

• Restrict riparian development & landowner property rights

• Grounded in municipal authority for public health, safety, public nuisances

• Generally DO NOT prescribe landcover – therefore only loosely connected to buffer function

“Except for support of biodiversity, some of the environmental services of

riparian areas can be provided by technologies, such as reservoirs for

flood control and treatment plants for pollutant removal. However, these

substitutions are directed at single functions rather than the multiple

functions that riparian areas carry out simultaneously and with little

direct costs to society.”

-National Research Council

Committee on Riparian Zone Functioning and Strategies for Management

Buffer Functions and Setbacks

•Flooding & Bank Storage

•Bank Erosion & Sedimentation

•Ambient Water Quality & Stream Temperature

•Water Supply - RBF

•Aquatic Ecosystems – through biological impairment & TMDLs

Excess Sedimentation

Estimated Damage Costs in the Atlanta Metropolitan Area:

$0.5 to $1 million in annual damage awards to downstream property owners

$1 to $5 million in additional drinking water treatment costs

$1 to $10 million in annual dredging costs

$1 to $10 million in additional maintenance costs for hydroelectric generating stations

$25 to $50 million in replacement costs for lost hydroelectric capacity.

DIRT2

•Grey literature on riparian services SPECIFICALLY to support riparian setback zoning – e.g. Wenger (1999) A review of the scientific literature on riparian buffer width, extent and vegetation. U. GA. Inst. Of Ecology

•Primarily Forest and Agricultural Buffer

•Two-edged sword!

1st Generation – Ag. and Forest buffer literature. What’s the “right” width?

2nd Generation - Riparian Function:

•Joint non-separable services flow from maintaining riparian function

•Emphasis on contiguity of riparian corridor and connection and exchanges between streams with their floodplains

Broadmeadow and Nisbet (2004) The effects of riparian forest management on the freshwater environment: a literature review of best management practice. Hydrology and Earth System Science 8(3):286-305

– after Barton,Taylor and Biette (1985) N. Amer. J. Fisheries Manage. 5:354-378

•Tradeoffse.g. stream temperatureWidth vs. Length

3rd Generation – Process-based Predictive Understanding

•Watershed-scale riparian services linked to landscape structure, position, and watershed dynamics

•Optimal buffer placement – design, design reliability, and safety factor

•Efficiency vs. Resilience of Riparian system – which setbacks matter most? Analogous to shift from technology-based to water quality-based standards

•Shei Pa National Park - Taiwan

Lin et al. (2004). Ecological Engineering 23:327-339

•Two-Edged Sword

Science Questions

Recovery and Reversibility – ‘Ghosts of Landuse Past’•French Broad, Little Tennessee Tennessee – 95% forest

Erosion Control & Bank Stability•Grass vs. Trees Volume vs. Residence Time

Stream Temperature•Width vs. Depth•Shading vs. Sheltering•“Recovery zones”

Significance of Bank Storage – e.g. Cedar River

Water Supply Services - River Bank Filtration (Louisville, Cincinnati, etc.)

Wood in Urban Streams - Stable wood vs. “debris”

Summary•Commoditization and policy-making regarding riparian services is accelerating (TMDLs, CBP)

•Demand for science to inform policy

•Process-based predictive understanding

•Beyond fluxes and stores: How does riparian continuity and connectivity affect resilience and reliability of riparian services?

Comments and Feedback WelcomeRiparian Setbacks; Technical Information for Decision Makers

www.crwp.org

Comments and Feedback WelcomeRiparian Setbacks; Technical Information for Decision Makers

www.crwp.org