Stormwater Net Environmental Benefit Analysis (NEBA) Case Study

Transcription

1 Stormwater Net Environmental Benefit Analysis (NEBA) Case Study How to Use the Habitat Equivalency Analysis Tool: Scientific/Measurement and Computational Challenges

2 Roadmap to Leaning Event Objectives Case Study Demonstration: NEBA of Stormwater Management Alternatives Part I: Scientific/Measurement Challenge How to use defensible off the shelf science in a NEBA Part II: Computational Considerations How to use the Habitat Equivalency Analysis (HEA) tool in NEBA

3 NEBA Purpose Net Environmental Benefits Analysis (NEBA) Quantitatively estimate the losses and gains of valued ecosystem services Compare Alternatives Riparian Restoration Proposal offered by WSDOT Conventional stormwater management for the SR 167 Extension Project. Select and Defend Preferred Alternative

4 Project Alternatives Baseline Condition: Without Treatment Alternative 1: Conventional Stormwater Treatment Proposal (CSTP) Alternative 2: Riparian Restoration Proposal (RRP)

5 Study Area

6 Hylebos Creek and Surprise Lake Drain Restoration Areas-- CSTP

7 Hylebos Creek and Surprise Lake Drain Restoration Areas-- RRP

8 Hylebos Creek

9 Wapato Creek Restoration Area--CSTP

10 Wapato Creek Restoration Area--RRP

11 Riparian Wetland PP--Wapato Creek Wapato Creek

12 Part II: Scientific/Measurement Challenges Define the ecosystem management goals What functions are the priorities for that system? Who decides? What metrics or combinations of metrics would provide measurable targets for the goals and would measure progress toward the goals? What primary services do the habitats provide? What indicators capture those services? Are those indicators responsive to the action?

13 Quantifying Resource Value Economists Recommended Approach is Service-Based Value of natural resource asset is found by summing the value of the flow of ecological services over time The closer the system comes to a fully functioning the greater the flow of ecological services and the higher the value of the natural resource

14 Habitat Equivalency Analysis: Ecological Currency The ecological currency unit is a measure of ecological services per habitat area per year e.g., dsays (discounted service acre years) One SAY = equivalent of one acre of a fully functioning reference habitat for 1 Year dsays = discounted SAYs (discounting converts SAYs to a common base year)

15 Discounted Service Acre Years % of Services Area B measures the change in dsays from increasing quality per acre from 6% function to 8%. B Time/Years

16 HEA Model Inputs Acres of habitat (Spatial extent of impact) Levels of ecological service (Depends directly on functionality of the system measured as a percentage of the reference condition) Time function (Measure of how the level of system function changes over time) Discounting (Process of converting future ecological services to their present day equivalent)

17 HEA Input: Habitat Types and Acreages What habitat types (e.g., wetlands, groundwater, forested uplands, stream riparian) are impacted? What is the aerial extent of the impact?

18 Habitat Equivalency Analysis (HEA) Inputs: Habitats Stream channel This habitat type is limited to the area of wetted channel within the ordinary high water mark in the Restoration Study Area. Riparian wetland This habitat type includes all wetlands delineated within the Restoration Study Area. Riparian upland This habitat type includes all remaining land area within the Restoration Study Area not identified as stream channel or wetlands.

19 HEA Input: Acreages Calculate acreage by habitat type for Baseline or No Treatment Condition Estimate acreage of each habitat that will be created under the CSTP and RRP Estimate acreage of each habitat that will be improved under the CSTP and RRP Estimate the acreage of each habitat that will be (- and/or +) impacted under the CSTP and RRP

20 Developing Ecological Service Metrics for Quantifying Environmental Benefits: Desirable Characteristics of an Ecological Currency Easy to measure, simple Captures the significant ecological functions and values Relates to identifiable ecosystem goal Responds to the stressors and management action (e.g., restoration) Captures differences in the spatial extent of the improvements

21 HEA Input: Changes in Ecological Services Habitat Type Riparian Wetlands Riparian Uplands Stream Channel Approach WDOT Wetland Function Characterization Approach National Marine Fisheries Service (NMFS) matrix of pathways and indicators for Salmonid NMFS matrix of pathways and indicators Function Hydrologic Water Quality Habitat Riparian Reserve (shade, large woody debris (LWD), recruitment, habitat protection, and connectivity in all subwatersheds) Habitat Elements (LWD, pool frequency, pool quality/depth, off-channel habitat, and refugia) Channel Conditions and Dynamics (Width/depth ratio, streambank condition, and floodplain connectivity)

22 Summary of Functions for Wetlands Function Rating Wetlands Hydrologic Water Quality Habitat Existing Moderate Moderate Low Future High High Moderate Functional Ratings of low, moderate, and high are defined by WDOT increase in service is assumed between function ratings

23 Riparian Upland Pathway and Functional Indicator Pathway Indicators Condition Ratings Watershed Conditions Riparian Reserve Existing NPF Future PF PF = Properly Functioning NPF = Not Properly Functioning

24 Stream Channel Pathways and Functional Indicators Example Hylebos Creek under the RRP Scenario Pathway HABITAT ELEMENTS Channel Conditions and Dynamics Indicators LWD Pool Frequency Pool Quality/Depth Off-Channel Habitat Refugia Width/Depth Ratio Streambank Condition Floodplain Connectivity Condition Ratings Existing Future NPF NPF NPF NPF NPF NPF NPF PF NPF PF FAR PF NPF PF NPF PF PF = Properly Functioning FAR = Functioning At Risk NPF = Not Properly Functioning

25 Summary of Stream Habitat Assumptions RRP Scenario Hylebos Creek Surprise Lake Drain Wapato Creek Indicator Enhance Restore Enhance Restore Enhance Restore LWD % % % % % % Pool Frequency % % % % % % Pool Quality/Depth % % % % % % Off-Channel Habitat % ++ % ++ % % Refugia % ++ % ++ % % Width/Depth Ratio % + 5% % + 5% % % Streambank Condition % % Floodplain Connectivity + 5% ++ % % % Average 19% 56% % 56% 19% % = no change or % + = increase one functional category (e.g., NPF to FAR, or FAR to PF) or 5% ++ = increase two functional categories (e.g., NPF to PF) or

26 Part III: Computational Considerations How to use the Habitat Equivalency Analysis (HEA) tool in NEBA 1. Compute the discounted sum of ecological services (DSAYS) under base condition 2. Compute the DSAYs under the Conventional Stormwater Treatment Proposal (CSTP) 3. Compute the difference between base condition and CSTP 4. Repeat the above 3 steps for the Riparian Restoration Proposal (RRP) 5. Compare the net DSAYs created by the RRP to the net DSAYs created by the CSTP

27 HEA Input Assumptions: Time Path for Changes in Ecological Services Time Function Project start Hylebos Creek/Surprise Lake Drain areas Wapato Creek Area - 22 Habitat recovery (Linear) Riparian Wetland and Upland - 8 years Stream Channel - 5 years End date Perpetuity Discounting Standard 3% discount rate Base year for discounting - 25

28 Baseline Services Provided by Habitat Model Inputs Habitat Type: Current Year Year discounting starts Discount Rate Year habitat starts providing services to public Initial aggregate measure of services from the habitat Maximum annual level of services that will ultimately be derived from one acre of the habitat, relative to initial aggregate services. Service level growth function from initial and continuing to the year that maximum productivity is achieved Riparian Wetland % 28 Linear

29 Baseline Services Provided by Habitat - Output Calculation of Benefits per Acre of Habitat Riparian Wetland 9 (a) (b) ( c) (d) Year Initial services provided by habitat Total Services = (Initial Services + Change in Services) Discounted Measure of Service per Acre of habitat [(b)/] x (d) Discount Factor s Total Each replacement project acre provides: DSAYs

30 Summary of DSAYs for all Habitats under Baseline Habitats EN Acreage RE UA IM EN DSAYs/Acre RE UA IM Ecological Value in DSAYs Riparian Wetland ,715 Riparian Wetland - AA.6 21 Riparian Wetland - BB.8 27 Riparian Wetland - CC.1 3 Riparian Wetland - DD.7 24 Riparian Wetland - Y Riparian Wetland - T Riparian Wetland - PP Riparian Wetland - QQ Riparian Wetland - RR Riparian Wetland SS 2 69 Riparian Wetland - UU Riparian Wetland - V 1 34 Riparian Wetland - H.5 17 Riparian Wetland Total ,561 EN Enhanced RE Relocated UA Unaffected IM - Impacted

31 Summary of DSAYs for all Habitats under Baseline cont. Habitats EN Acreage RE UA IM EN DSAYs/Acre RE UA IM Ecological Value in DSAYs Riparian Uplands H Riparian Uplands - SL Riparian Uplands - W 6.1 2,61 Riparian Uplands Total ,92 Stream Channel - H Stream Channel - SL.1 3 Stream Channel - W Stream Channel Total EN Enhanced RE Relocated UA Unaffected IM - Impacted

32 Services Provided by Habitat under Conventional Storm water Treatment Proposal (CSTP) Model Inputs Current Year Year discounting starts Discount Rate Active Restoration/Rehab Start Year End Year for Active Restoration/Rehab Habitat Type: Number of years following COMPLETION of active restoration project before the maximum service level is reached. Initial aggregate measure of services from the habitat Total annual aggregate measure of services from the habitat during first year of active restoration, relative to baseline services. Total annual services from habitat during final year of active restoration, relative to baseline services. Maximum annual level of services that will ultimately be derived from one acre of the enhanced / rehabilitated habitat, relative to baseline services for the habitat. Service level growth function during restoration phase Service level growth function following active restoration and continuing to the year that maximum productivity is achieved Riparian Wetland % % Linear Linear

33 Services Provided by Habitat Under CSTP- Output Calculation of Benefits per Acre of Habitat Riparian Wetland 9 (a) (b) ( c) (d) Year Initial services provided by habitat Total Services = (Initial Services + Change in Services) Discounted Measure of Service per Acre of habitat [(b)/] x (d) Discount Factors % % % % %.15.7 Total Each replacement project acre provides: 62.2 DSAYs

34 Services Provided by Habitat Under CSTP Total Services from One Acre of Enhanced Habitat, Relative to Baseline Services for Habitat Time

35 Summary of DSAYs for all Habitats under CSTP Habitats EN Acreage RE UA IM EN DSAYs/Acre RE UA IM Ecological Value in DSAYs Riparian Wetland Riparian Wetland - AA.6 21 Riparian Wetland - BB.8 27 Riparian Wetland - CC Riparian Wetland - DD.7 24 Riparian Wetland - Y Riparian Wetland - T Riparian Wetland - PP Riparian Wetland - QQ Riparian Wetland - RR Riparian Wetland SS 2 69 Riparian Wetland - UU Riparian Wetland - V Riparian Wetland - H.5 17 Riparian Wetland Total EN Enhanced RE Relocated UA Unaffected IM - Impacted

36 Summary of DSAYs for all Habitats under CSTP cont. Habitats EN Acreage RE UA IM EN DSAYs/Acre RE UA IM Ecological Value in DSAYs Riparian Uplands - H Riparian Uplands - SL Riparian Uplands - W Riparian Uplands Total Stream Channel -H Stream Channel - SL Stream Channel - W Stream Channel Total EN Enhanced RE Relocated UA Unaffected IM - Impacted

37 Services Provided by Habitat under Riparian Restoration Proposal (RRP) Model Inputs Current Year Year discounting starts Discount Rate Active Restoration/Rehab Start Year End Year for Active Restoration/Rehab Habitat Type: Number of years following COMPLETION of active restoration project before the maximum service level is reached. Initial aggregate measure of services from the habitat Total annual aggregate measure of services from the habitat during first year of active restoration, relative to baseline services. Total annual services from habitat during final year of active restoration, relative to baseline services. Maximum annual level of services that will ultimately be derived from one acre of the enhanced / rehabilitated habitat, relative to baseline services for the habitat. Service level growth function during restoration phase Service level growth function following active restoration and continuing to the year that maximum productivity is achieved Stream Channel Hylebos Creek Relocated % % Linear Linear

38 Services Provided by Habitat Under RRP- Output Calculation of Benefits per Acre of Habitat Stream Channel Hylebos Creek (a) (b) ( c) (d) Year Initial services provided by habitat Total Services = (Initial Services + Change in Services) Discounted Measure of Service per Acre of habitat [(b)/] x (d) Discount Factors % % % % % % 156%.15.7 Total Each replacement project acre provides: 49.6 DSAYs

39 Services Provided by Habitat Under RRP Total Services from One Acre of Enhanced Habitat, Relative to Baseline Services for Habitat Time

40 Summary of DSAYs for all Habitats under RRP Acreage DSAYs/Acre Ecological Value in DSAYs Habitats EN RE UA IM EN RE UA IM Riparian Uplands - H Riparian Uplands - SL Riparian Uplands - W Riparian Uplands Total Stream Channel - H Stream Channel - SL Stream Channel - W Stream Channel Total EN Enhanced RE Relocated UA Unaffected IM - Impacted

41 Summary of DSAYs for all Habitats under RRP cont. Habitats EN Acreage RE UA IM EN DSAYs/Acre RE UA IM Ecological Value in DSAYs Riparian Wetland Riparian Wetland - AA Riparian Wetland - BB Riparian Wetland - CC Riparian Wetland - DD Riparian Wetland - Y Riparian Wetland - T Riparian Wetland - PP Riparian Wetland - QQ Riparian Wetland - RR Riparian Wetland SS Riparian Wetland - UU Riparian Wetland - V Riparian Wetland - H Riparian Wetland Total EN Enhanced RE Relocated UA Unaffected IM - Impacted

42 NEBA Results Comparison 7, , 5, 4, 3, 2, 1, ,471 2,99 2, Baseline CSTP RRP Riparian Wetlands Riparian Uplands Stream Channel

43 Outcomes for WSDOT NEBA was incorporated into the EIS and used to compare alternatives and select the preferred alternative Washington Secretary of the Department of Transportation indicated he wants WSDOT to investigate the applicability of this tool for their other large projects!!

44 Current/Future Opportunities NEPA Documentation Facility Siting Environmental Credit Trading Total Lands Solutions DOD BRAC, Water Supply, Other? DOT Pilot Studies For innovative Clients Large Land Holders (e.g., Timber, Chemical, and Utilities), TVA

45 Thank you!