Takings vs. Givings: Science and Policy in Riparian Setback Zoning Stu Schwartz Center for Urban Environmental Research and Education University 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?

2 nd 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): – after Barton,Taylor and Biette (1985) N. Amer. J. Fisheries Manage. 5: Tradeoffs e.g. stream temperature Width vs. Length

3 rd 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: Two-Edged Sword

Science Questions Recovery and Reversibility – ‘Ghosts of Landuse Past’ French Broad, Little TennesseeTennessee – 95% forest Erosion Control & Bank Stability Grass vs. TreesVolume 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 Welcome Riparian Setbacks; Technical Information for Decision Makers

Comments and Feedback Welcome Riparian Setbacks; Technical Information for Decision Makers