Selecting Wetland Mitigation Sites Using A Watershed Approach
Selecting Wetland MitigationSites Using aWatershed ApproachThomas Hruby, Kim Harper, and Stephen StanleyEcology Publication #09-06-032December 2009Page is blank – back page of cover
Page is blank – back page of cover
Selecting Wetland Mitigation Sites Usinga Watershed ApproachEcology Publication #09-06-032December 2009Written by: Thomas Hruby1, Kim Harper2, and Stephen Stanley1Technical Advisors: Patricia Johnson3, Susan Meyer1, Linda Storm4,Gail Terzi5 and Mary Anne Thiesing41.2.3.4.5.Washington Department of EcologyWashington Department of Ecology Liaison to U.S. Army Corps of EngineersWashington Department of Ecology (currently with Puget Sound Partnership)U.S. Environmental Protection Agency, Region 10U.S. Army Corps of Engineers, Seattle District
For more information about the project, to send in comments on the document, or if you havespecial accommodation needs, contact:Thomas HrubyDepartment of EcologyP.O. Box 47600Olympia WA 98504Telephone: (360) 407-7274Email: tom.hruby@ecy.wa.govOr visit our home page at www.wa.gov/ecology/sea/shorelan.htmlMake sure you have the most recent version of this documentDue to the dynamic nature of wetland science, this document is subject to revision. Aswe learn more on the science of wetland restoration, and as we receive suggestions fromusers for improving this guide, the document will be periodically updated. Make sureyou have the most recent version. You can find the most up-to-date version at:www.ecy.wa.gov/mitigation/resources.html.This report should be cited as:Hruby, T., K. Harper, and S. Stanley (2009). Selecting Wetland Mitigation Sites Usinga Watershed Approach. Washington State Department of Ecology Publication #09-06-032.Ecology is an equal opportunity and affirmative action agency and does not discriminate onthe basis of race, creed, color, disability, age, religion, national origin, sex, marital status,disabled veteran’s status, Vietnam Era veteran’s status or sexual orientation.
Table of ContentsFigures and Charts . iSelecting Wetland Mitigation Sites Using a Watershed Approach . 1Background . 1Scope of this Guide . 2Who Should Use This Guide . 3The Process for Selecting Mitigation Sites . 4PART 1: Analyzing Mitigation Sites at a Watershed Scale . 7Following One of Two Paths . 8Using the Charts . 10PART 2: Analyzing the Suitability of an Individual Site for Mitigation . 18The Changing Science of Mitigation . 18Key Points in Designing the Restoration or Enhancement of Wetlands . 19Charts 4 – 5: Can a site be used to improve hydrologic functions? . 22Charts 6 – 9: Can a site be used to improve water quality functions? . 22Charts 10 – 11: Can a site be used to improve habitat? . 23Definitions. 33Other Resources . 34References . 35APPENDIX A – Achieving an Ecosystem Based Approach to Planning in the Puget Sound . 37APPENDIX B – Worksheets for Charts 4 through 11 . B-1Figures and ChartsFigure 1: Process for Selecting Mitigation Sites. 5Figure 2: Six Steps in Planning a Mitigation Project . 21Chart 1: Analyzing Potential Wetland Mitigation Sites Using Existing Watershed Plans . 11Chart 2: Analyzing Potential Wetland Mitigation Sites Without a Watershed Plan . 12Chart 3: Analyzing the Potential of Sites to Provide Sustainable Mitigation in a WatershedContext . 13Chart 4: Goal - Improving Hydrology Functions in Riverine/Floodplain Systems . 24Chart 5: Goal - Improving Hydrology Functions in Depressional Systems Outside ofFloodplains . 25Chart 6: Goal - Improving Water Quality (WQ) Functions in Riverine/Flood-plain Systems . 26Chart 7: Goal - Improving Water Quality (WQ) Functions in Depressional Systems Outside ofFloodplains . 27Chart 8: Goal - Improving Water Quality (WQ) Functions Along the Shores of Lakes . 28Chart 9: Goal - Improving Water Quality (WQ) Functions in Slope Systems . 29Chart 10: Goal - Improving Species Richness of Wildlife . 30Chart 11: Goal - Improving Species Richness of Plants . 31Selecting Wetland Mitigation Sites Using a Watershed ApproachDecember 2009i
Selecting Wetland Mitigation Sites Using a Watershed ApproachDecember 2009ii
Selecting Wetland Mitigation Sites Using a WatershedApproachThe Washington Department of Ecology (Ecology), U.S. Army Corps of Engineers SeattleDistrict (Corps), and the U.S. Environmental Protection Agency Region 10 (EPA) (collectivelythe Agencies) prepared this guide on selecting mitigation sites for unavoidable wetland impacts.The Agencies encourage state, federal, and local decision-makers, as well as project applicants,to use this guide as one step in the process of making decisions on compensatory mitigationprojects. The goals of this guide are to improve mitigation success and to better address theecological priorities of Washington’s watersheds. We provide specific recommendations onhow to apply a watershed approach when selecting sites and in choosing between on-site andoff-site mitigation in western Washington. A similar guide is planned for eastern Washington.Use of this guide is not required by the authoring agencies, but the federal rule on compensatorymitigation does require that some type of watershed approach be used in siting mitigation. Thisguide is offered as one way to fulfill that requirement.BackgroundPermitting agencies requirecompensatory mitigation whenapplicants cannot reasonably avoid allimpacts to wetlands and their functionsand values. State and national studies ofwetland mitigation, however, show adisappointingly low success rate inmeeting performance measures andreplacing wetland functions (Ecology2002; National Research Council 2001).The studies identify a number of reasonsfor this including poor site selection.Our past policies and practices haveover-emphasized the need to replace lostfunctions at or near the wetlandsimpacted (the impact site), rather thanchoosing mitigation sites that best fitwith the mitigation goals of the projectand its contributing basin. The studiesdemonstrate a clear need to change thisapproach.Watershed Approach: A watershed approachwhen used in selecting sites for mitigation isbased on:1. Understanding how ecological processes,such as the movement of water, determinethe characteristics and ecological functions ina drainage basin (watershed). NOTE: There areno size limits to the drainage basin used for theanalysis. A watershed approach can be used in smalldrainage basins that are only several square miles insize to entire river basins such as the SnohomishRiver.2. Determining the extent to which theprocesses have been altered (e.g., change ingroundwater flows resulting from loss offorests).3. Identifying areas where these processes canbe most effectively restored, and where theyneed to be protected.4. Assessing the role restoration, includingcompensatory mitigation, can play inrepairing those processes and replacingwetland functions lost in the watershed.In the last ten years we have seen a shiftin national and state policies towards using a watershed-based approach to choose mitigationsites. Recent guidance recommends that mitigation be done in areas where ecological processesSelecting Wetland Mitigation Sites Using a Watershed ApproachDecember 20091
can best be restored, unless it is necessary to maintain the affected functions on or near theimpact site (Ecology et al. 2006, USACE & EPA 2008). While this shift in policy is becomingwidespread among regulatory agencies1, we see a lag in applicants actually using a watershedapproach when selecting mitigation sites. This guide clarifies our agencies’ support of thischange and provides practical tools that will help close this gap.This guide promotes mitigation that is located appropriately on the landscape, addressesrestoration of watershed processes, is sustainable, and has a high likelihood of ecologicalsuccess. On-site mitigation may achieve these goals in many circumstances. However, weshould not risk mitigation success or bypass opportunities for improving ecological processes ina watershed by unnecessarily prioritizing on-site mitigation over more effective and sustainableoff-site options.Appendix A (a separate document available at: www.ecy.wa.gov/mitigation/resources.html. )presents more information on the importance of using a watershed planning framework andincludes an example of how watershed planning can be applied to identify solutions to specificproblems in a watershed. This appendixSustainable mitigation sitealso explains the connection betweenMitigation is often targeted at replacingecological processes and wetland structurespecific functions at a site. The goal is toand functions.maintain these functions for many years intoScope of this Guidethe future. A site is considered sustainable ifthe functions can be maintained without longterm management or maintenance.Unfortunately, many watersheds have been soheavily disturbed by human activities that thefunctions at a site can no longer be maintainedby ecological processes in that watershed. Inthis case, a site is considered not sustainablebecause maintaining the functions in time willrequire continuous management to counteractthe effects of the altered processes.This guide is meant to help users select thebest locations for wetland mitigation sites.The Agencies recognize that selecting a siteis a complex process involving manyvariables. This guide simplifies the processby asking questions that characterize thepotential of a site to be sustainable, restorewatershed processes, and replace thefunctions lost in other wetlands. The guidedoes not help users to design site-specific mitigation plans, although it does identify someissues that need to be addressed in a mitigation plan. There are two parts to this guide: Part 1guides users in locating a mitigation site by analyzing the watershed and its generalfunctions. Analyzing the watershed also helps determine whether a potential site will besustainable.Part 2 characterizes the constraints and issues that might be present in, or immediatelyadjacent to, a site. This analysis can be used to determine what functions can be mitigated at asite. It also identifies the major elements that need to be included in a mitigation plan specificto the site.1Most local jurisdictions in Washington that have revised their critical areas ordinances (CAOs) in the past 5 yearsnow allow for off-site mitigation, typically with a preference for it being within the same drainage basin, sub-basinor watershed as the impact site. Many include language urging consideration of landscape principles in sitingmitigation. In some cases, limits by local CAOs may necessitate modifying the methods used in this guidance.Selecting Wetland Mitigation Sites Using a Watershed ApproachDecember 20092
This guide does not include strategies for avoiding or minimizing impacts. We assume thatthis step in the mitigation process has been taken before the need for compensatory mitigationis established. For existing information on avoidance and minimization of impacts see thedocuments listed below. Additional guidance on this topic is being developed by federalagencies and is expected to be published in 2010.Compensatory Mitigation for Losses of Aquatic Resources, Final Rule, 33 CFR Parts 325and 332 and 40 CFR Part 230(http://www.epa.gov/owow/wetlands/pdf/wetlands mitigation final rule 4 10 08.pdf)Regulatory Programs of the Corps of Engineers, Final Rule, 33 CFR Part idx?c ecfr&tpl /ecfrbrowse/Title33/33cfr320 main 02.tpl)Regional limits of this guide:This guide is intended to be used in western Washington, west of the Cascade Divide.We do not advise using it in the semi-arid areas east of the Cascade Range where thegeology and rainfall patterns are quite different. In the future, we hope to develop aseparate guide for selecting mitigation sites in eastern Washington.This guide is not intended to be used in locating estuarine mitigation sites as it does notaddress many of the ecological processes at work in estuarine settings. The Agenciescontinue to support a policy of compensating for impacts to estuarine wetlands bymitigating in estuarine settings.This guide considers ecological processes in floodplain areas but it does not addressmitigating for in-channel stream impacts.Who Should Use This GuideThis is a technical guide intended for use by wetland consultants, biologists, hydrologists andother practitioners with some familiarity with landscape processes. It is important that theperson applying this tool have experience and/or education in hydrologic processes and howthey affect wetland functions. The guide will typically be used by those designing wetlandmitigation. We advise permit applicants who need to mitigate for adverse wetland impacts tohire a qualified consultant to apply the approach explained in this document.Selecting Wetland Mitigation Sites Using a Watershed ApproachDecember 20093
Making Choices Using a Watershed ApproachIn urbanizing areas, many functions wetlands provide may not be sustainable long term. Thismay be particularly true for wetlands in a highly altered landscape where ecological processesare unlikely to be restored and losses in wetland functions are expected to increase withdevelopment (Azous and Horner 2001). In such cases, it may be preferable to compensate forimpacts to those wetlands by locating mitigation sites in nearby drainages that have a lesserdegree of urbanization. In this way, the mitigation site has greater potential to provide functionsover time. By reducing the risk of failure that results from ongoing development, we canachieve a net gain in wetland functions and also restore lost or damaged watershed processes.In some cases proposed alterations to a wetland will impact a function or value that is veryimportant in the immediate area of the site. For example, a wetland in an urban area mayprovide significant recreational and educational opportunities for local residents. Also, thewetland may be receiving untreated stormwater, thus providing water quality and hydrologicfunctions to the immediate area. These types of functions and services may need to be replacedon-site. If so, it may be necessary to mitigate at two sites: on-site to replace the functions andservices that cannot be moved elsewhere and off-site for all the rest. For example, if a wetlandthat will be impacted is retaining stormwater, a stormwater facility can be built on-site and theother functions, such as habitat, can be replaced elsewhere. In many cases in urban areas, thelandscape setting may preclude replacing habitat functions on site unless the project sponsorprovides intensive long-term management and maintenance.Current research indicates that on-site mitigation in urban and urbanizing areas is notsustainable without continual monitoring and maintenance to counteract the effects of humandisturbance. For example, re-creating a plant community indicative of less disturbed conditionswill require continual removal of opportunistic (invasive) species that are better adapted todisturbed sites.The Process for Selecting Mitigation SitesIt is a complex process to select a mitigation site that has a good chance of being sustainableand that also compensates for the functions and services (also called “values”) lost at the impactsite. First, you must identify the functions and services lost at the impact site, then you must tryto find a site where those functions and services can be compensated, and finally you mustdetermine if the mitigation will be feasible and sustainable. Figure 1 provides a graphicalrepresentation of the steps that must be taken in selecting an appropriate mitigation site. Thisguide addresses only two of the steps in the process (shown in red font): 1) selecting potentialsites using information from the surrounding hydrologic unit (see definitions below) and 2)identifying constraints that may be found at individual sites.Selecting Wetland Mitigation Sites Using a Watershed ApproachDecember 20094
Figure 1: Process for Selecting Mitigation SitesNote: This document provides information on only the two steps that are shown in red font with boxeshighlighted by a shadow.Is there any way you could avoid impacts towetlands and their buffers?[Guidance on avoidance and minimization isforthcoming]No mitigationneededYesNoIs there any way you could further minimizeimpacts to wetlands and their buffers?YesRedesign your project tominimize impacts.NoDevelop a mitigation plan forthe site that:Determine what functions and services will belost when you alter the wetland, and the totalarea of impacts.Removes environmentalconstraintsImproves ecologicalprocesses.Identify sites that could be used forcompensatory mitigation and assess theirsustainability using Part 1 in this guidance.YesNoDoes the site meet the requirements ofCharts 1, 2, 3 in this guide?NoYesYesAnalyze the constraints at the site that mightprevent you from meeting your objectives inmaintaining or improving functions andservices. Use Part 2 of this guidance.Will theYesmitigationyou propose at thesite improve orpreserve functionsand services that havebeen found critical ina watershed plan, andmeet the requiredratios for the area ofimpacts?NoAre there constraints at the site that wouldprevent you from replacing the functions andservices lost or maintaining or improvingimportant functions in the hydrologic unit?YesNoSelecting Wetland Mitigation Sites Using a Watershed ApproachYesWill the mitigation you proposecompensate for the functions andservices lost through your activities,and meet the required ratios for thearea of impacts?
This guide is intended to be used in western Washington, west of the Cascade Divide. We do not advise using it in the semi-arid areas east of the Cascade Range where the geology and rainfall patterns are quite different. In the future, we hope to develop a separate guide for selecting mitigation sites in eastern Washington.
wetland ecosystem. The boundary of the wetland is identified by changes in vegetation structure, loss of hydrophytes, and wetland soil characteristics. This wetland definition encom-passes a wide range of ecosystems, from semi-terrestrial fens, bogs, and swamps to semi-aquatic marshes and shallow open water. Excluded from the definition are
list the biotic and abiotic factors in a wetland. 3) Using the list of organisms that they observed and would expect to observe in a wetland, have students create an energy pyramid of a wetland ecosystem on the “Energy Pyramid” worksheet.
In this paper, the effectiveness of the wetland plant Canna indica and . sedimentation etc In this paper Grey water is treated using Modified Rooty zone system in Wetland Column. . (m2/pe) is the one of the major design parameter that is used in practice. The surface area requirement for the treatment of wastewater in constructed wetland .
An assortment of wetland plant and animal pictures on page 6 Yarn Materials A Wetland Web Wetland Connections Minnesota Valley National Wildlife Refuge 1. Continuing from the “Wetland Food Chains Activity,” randomly pass the pictures to all team members until all pictures are used. 2. Start with the lowest component of the food web .
wetland, freshwater wetland or property line that decreases the shortest existing nonconforming setback distance from the water body, great pond, stream, tributary stream, coastal wetland, freshwater wetland
Lesson Plan Lesson Preparation Review the Science Background provided in the Unit’s Overview and the Teacher Reading Wetland Ecosystems. Review and prepare copies of student reading Ecosystem Interdependence, Food Chain & Carbon Cycle worksheet and Wetland Note-taking worksheet, one for each student. Preview PowerPoint Introduction to Wetlands “Hawai‘i’s Wetland Ecosystems .
2. The IWC will be a tool for the surveillance of wetland extent and condition over a 10-20 year timeframe. 3. The IWC will be suitable for use at a wetland at any time of year. 4. The IWC will be designed to assess wetland condition in a single visit. 5. The IWC will be a rapid assessment tool. 6. The IWC will be simple, straightforward and .
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