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Chapter 7. Hydromodification 1



## Chapter 7. Hydromodification 1

1 

### Contents 2 1 Overview.........................................

................................................... ....................................... 3 3 1.1 Sources........................................

................................................... ...................................3 4 1.1.1 Streambank and Shoreline Erosion.............

................................................... ..........4 5 1.1.2 Channelization ...............................

................................................... .......................4 6 1.1.3 Dams and In-stream Structures................

................................................... .............5 7 1.1.4 Contribution .................................

................................................... .........................5 8 2

. Chesapeake Bay Hydromodification Implementation Me asures............................................. . 7 9 2.1 General Principles and Goals...................

................................................... ......................7 10 2.2 Implementation Measures........................

................................................... ......................8 11 2.2.1 Implementation Measure #1: Protect Streambank s and Shorelines from 12 Erosion ............................................

................................................... ......................9 13 2.2.1.1 Existing Practices.........................

................................................... ......... 9 14 2.2.1.2 Multi-Cell Culvert.........................

................................................... ........ 9 15 2.2.1.3 Non-eroding Roadways ....................... .................................................. 1 0 16 2.2.1.4 Riprap.....................................

................................................... ............. 13 17 2.2.1.5 Toe Protection.............................

................................................... ........ 13 18 2.2.2 Implementation Measure #2: Control Upland Sou rces of Sediment and 19 Nutrients at Dams ..................................

................................................... .............14 20 2.2.2.1 Existing Practices.........................

................................................... ....... 14 21 2.2.3 Implementation Measure #3: Restore In-stream and Riparian Habitat 22 Function ...........................................

................................................... ...................15 23 2.2.3.1 Existing Practices.........................

................................................... ....... 16 24 2.2.3.2 Shoreline Sensitivity Assessment ........... ............................................... 16 25 2.2.3.3 Establish and Protect Stream Buffers ....... ............................................. 17 26 2.2.3.4 Riparian Improvements......................

................................................... . 20 27 2.2.3.5 Vegetated Buffers ..........................

................................................... ..... 21 28 2.2.3.6 Vegetated Filter Strips ....................

................................................... .... 22 29 2.2.4 Implementation Measure #4: Reduce Pollutant S ources through Operational 30 and Design Management..............................

................................................... .......23 31 2.2.4.1 Existing Practices.........................

................................................... ....... 23 323/15/20 2

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Chapter 7. Hydromodification 2

2.2.4.2 Advanced Hydroelectric Turbines ............ ............................................. 24 1 2.2.4.3 Flow Augmentation ..........................

................................................... .. 24 2 2.2.4.4 Selective Withdrawal.......................

................................................... ... 26 3 2.2.4.5 Turbine Operation..........................

................................................... ..... 27 4 2.2.4.6 Turbine Venting............................

................................................... ...... 27 5 2.2.5 Implementation Measure #5: Restore Stream and Shoreline Physical 6 Characteristics....................................

................................................... .................28 7 2.2.5.1 Existing practices.........................

................................................... ....... 29 8 2.2.5.2 Bank Shaping and Planting.................. .................................................. 3 0 9 2.2.5.3 Brush Mattressing ..........................

................................................... ..... 30 10 2.2.5.4 Cross Vanes ................................

................................................... ........ 31 11 2.2.5.5 Joint Planting .............................

................................................... ......... 32 12 2.2.5.6 Legacy Effects of Dams and Dam Removal..... ..................................... 33 13 2.2.5.7 Live Crib Walls............................

................................................... ....... 38 14 2.2.5.8 Live Fascines ..............................

................................................... ........ 39 15 2.2.5.9 Live Staking...............................

................................................... ......... 41 16 2.2.5.10 Log & Rock Check Dams..................... ................................................. 43 17 2.2.5.11 Marsh Creation and Restoration ............ ................................................ 44 18 2.2.5.12 Revetments................................

................................................... .......... 45 19 2.2.5.13 Rock and Log Vanes........................

................................................... ... 46 20 2.2.5.14 Rosgen’s Stream Classification Method..... ........................................... 47 21 2.2.5.15 Step Pools................................

................................................... ............ 59 22 2.2.5.16 Streambank Dewatering.....................

................................................... . 60 23 2.2.5.17 Vegetated Gabions.........................

................................................... ..... 61 24 2.2.5.18 Vegetated Geogrids........................

................................................... ..... 61 25 2.2.5.19 Vegetated Reinforced Soil Slope (VRSS) .... ......................................... 62 26 2.2.5.20 Weirs.....................................

................................................... .............. 62 27 2.2.5.21 Wing Deflectors...........................

................................................... ....... 63 28 3 References.......................................

............................................. Appendix A. Sources of Data 29 66 303/15/20 2

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Chapter 7. Hydromodification 3 

## 1 Overview 1 The Chesapeake Bay and its tributaries, representin g the nation’s largest estuary, is a 2
resource resources of important economic, social and environmental si gnificance. The 3 Chesapeake Bay ecosystem, however, remains severelydegraded primarily because of pollution 4 from excess nitrogen (N), phosphorus (P) , phosphorous , and sediment, which enters surface 5 waters. Those pollutants come from multiple diverse sources within the Chesapeake Bay 6 watershed, but the primary sources are agriculture, urban and suburban runoff, wastewater , and 7 airborne contaminants ( Chesapeake Bay Program CBP 2009). One source that has been identified 8 as a contributor of pollutants to the Chesapeake Ba y is hydromodification. EPA Region 3 states 9 report that, of as sessed waters

— a cumulative total of 1,427 miles of assessed rivers and streams, 10 1,687 acres of assessed lakes and reservoirs, and 1,916 square miles of assessed bays and 11 estuaries—hydromodification is the probable source contributing to impairments. 12
The term hydromodification as used in this guidance refers to the “alteration of the hydrologic 13 characteristics of waterbodies, which in turn could cause degradation of water resources.” Many 14 activities that are considered forms of hydromodifi cation have been conducted and continue to 15 be conducted because they are considered to be crit ical to human activities, such as dredging 16 shipping channels for commerce or constructing culv erts at stream crossings for transportation. 17 Hydromodification can also refer to activities thatare conducted in and adjacent to stream 18 channels to maintain stream functions or reduce dam age to streams or adjacent properties such as 19 clearing of debris or armoring of streambanks. 20 While hydromodification activities likely occurred within the Chesapeake Bay watershed before 21 European settlement (e.g., fish traps, secondary ef fects from riparian agriculture) the scale and 22 scope of hydromodification increased dramatically w ith the advent of European expansion on the 23 east coast of North America. Early settlers constru cted dams to harness hydropower and drained 24 floodplain areas for farming (Walter and Merritts 2008; Schenk and Hupp 2009). (Walter et al

. 25 2008 ; Schenk et al

. 2009). As development accelerated through the colonial, p ost revolutionary 26 and industrial periods hydromodification activities expanded to include dredging of natural and 27 man-made waterways for commerce, construction of wa ter supply, recreational and flood control 28 dams, and channel straightening and dredging for fl ood control and agriculture. In more recent 29 years , development of the built environment has resulted in secondary channel erosion within 30 and downstream of urban centers. 31



### 1.1 Sources 32 Hydromodification activities are grouped into three general categories for the purposes of this 33 document: (1) channelization and channel modificati on, (2) dams, and (3) streambank and 34 shoreline erosion. Such broad categories are useful in that they provide a logical organization for 35 hydromodification activities. However, as is descri bed later in this document, implementation 36 measures and practices can apply across these three activity categories. In addition certain 37 hydromodification activities might not fit neatly w ithin any of the three categories describe d 38 below

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Chapter 7. Hydromodification 4 

### 1.1.1 Streambank and Shoreline Erosion 1 Streambanks and shoreline erosion refers to the deg radation of stream, estuary and lake shore 2 areas resulting in loss of soil and other material landward of the bank along non-tidal streams and 3 rivers. Streambank erosion occurs when the force of flowing water in a river exceeds the ability 4 of soil and vegetation to hold the banks in place. Eroded material is carried downstream and re5 deposited in the channel bottom or in point bars lo cated along bends in the waterway. Shoreline 6 erosion occurs in large open waterbodies, such as l arger lakes and the lower estuarine portion of 7 the Chesapeake Bay, where waves and currents sort c oarser sands and gravel from eroded bank 8 materials and move them in both directions along th e shore away from the area being eroded. 9 While the underlying forces causing the erosion cou ld be different for streambank and shoreline 10 erosion, the results, erosion and its impacts, are usually similar. It is also important to note that 11 streambank and shoreline erosion are natural proces ses and that natural background levels of 12 erosion also exist and might be necessary to ensure the health of a particular stream. However, 13 human activities along or adjacent to streambanks o r shorelines can increase erosion and other 14 nonpoint sources of pollution. 15



### 1.1.2 Channelization 16 Channelization and channel modification include act ivities such as straightening, widening, 17 deepening, and clearing channels of debris and accu mulated sediment. Examples of 18 channelization and channel modification projects in clude flood control, infrastructure protection, 19 channel and bank stabilization, habitat improvement /enhancement, recreation, and flow control 20 for water supply (source). Channelization activitie s play an important role in nonpoint source 21 pollution effect on the Chesapeake Bay by affecting the timing and delivery of pollutants that 22 enter the water. Channelization can also be a cause of higher flows during storm events, which 23 increases the risk of flooding. 24 Historically, channelization occurred to reduce flo oding, drain wet areas for agriculture and to 25 allow for commerce among, other reasons. In recent years however regulatory requirements 26 primarily driven by the Clean Water Act ( US EPA 1972) have limited traditional 27 hydromodification activities within stream channels and waterbodies. Simultaneously, water 28 resource managers have recognized the critical role that healthy stable stream corridors play in 29 the protection and improvement of water quality andliving resources within the Chesapeake 30 Bay. As a result many of the hydromodification acti vities occurring currently are those related to 31 maintenance and restoration of channel corridors an d shorelines. 32 One type of hydromodification activity that is attr acting increased attention by water resource 33 professionals as a possible source of pollutants, a nd overall degraded health of stream benthic 34 communities, is the erosion of streambanks in unstable streams particularly in urban and 35 suburban areas. Previously researchers theorized th at the principle predictor of stream health and 36 instability in urbanizing watersheds was impervious ness. Furthermore, it was initially reported 37 that channel instability and reduced benthic health generally occurred once imperviousness 38 passed 10 percent (Schueler 1994). As a result of t hese findings many water resource protection 39 agencies developed stormwater management regulation s based on restrictions of imperviousness 40 (need example). Subsequent research however has sho wn substantial effects on the stream health 41 and stability across all levels of imperviousness ( Booth et al. 2004). As a result many agencies 423/15/20 2

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Chapter 7. Hydromodification 5 are shifting the focus of stormwater management to those practices that control the causative 1 factors of stream instability, namely changes in wa tershed hydrology. This topic is covered in the 2 Urban chapter of this guidance. 3



### 1.1.3 Dams and In-stream Structures 4 Dams and in-stream structures are artificial barrie rs on waterbodies that control the flow of 5 water. These structures can be built for a variety of purposes, including flood control, power 6 generation, irrigation, navigation, and to create p onds, lakes and reservoirs for uses such as 7 municipal water supply, fish farming and recreation . While these types of structures are 8 constructed to provide benefits to society, they ca n contribute to nonpoint source pollution and 9 effects on living resources. For example dams can a lter flows which with ultimately can cause 10 effects on water quality and roadway culverts can r esult in the scour of stream sediments at their 11 outlet. While these structures were often built for purposes related to human needs in many cases 12 that need is no longer present (e.g., small hydropo wer dams to support manufacturing). As a 13 result water resource managers have conduct eddetailed cost benefit analysis at many dams and 14 the result often show that the benefits of dam remo val outweigh the benefits of continuing to 15 maintain and operate the dam. 16 An important development in the effect of dams in w ater quality is the increasing trend of 17 agencies and dam removal within the Chesapeake Bay as dams reach their life expectancy and 18 are removed for safety concerns or to restore the c onnectivity of aquatic ecosystems. This 19 phenomenon is covered extensively in one of the pra ctices recommended later in this document. 20



### 1.1.4 Contribution 21 The contribution of hydromodification activities to sediments and nutrient loads to the 22 Chesapeake Bay is poorly defined in the current res earch literature. Traditionally land use 23 managers and water resources professionals categori zed these pollutant loadings based on 24 specific land uses (such as agricultural, urban andsilviculture). Contribution of specific 25 hydromodification activities such as channel erosio n or dams was less well defined. With recent 26 research on the topic however increased attention a nd research activity has been focused on 27 separating the contribution of specific activities such as stream corridor instabi lity to overall 28 pollutant loading of the bay. 29 The interaction between pollutants from upland sour ces and those which originate within the 30 stream corridor is a complex one. During the 1700s and 1800s eroding upland agricultural areas 31 resulted in significant sediment storage within str eam corridors typically called legacy sediment 32 ( USGS Langland and Cronin 2003). The construction of Mill dams during within this same period 33 resulted in the impoundment and storage of sedimentbehind tens of thousands of mill dams in 34 the mid-Atlantic region (Merrit et al.2004) . Subsequent removal of these dams during the late 35 industrial period and urban and suburban developmen t in the past 100 years has led to erosion of 36 the deposited sediments as stream corridors have be come instable and streambanks have eroded 37 (USGS 2003 2005 ). 38 Because of the intimate nature of hydromodification activities with the stream corridor there is 39 understandably a close relationship between those a ctivities and sediment delivery to surface 403/15/20 2

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Chapter 7. Hydromodification 6 waters. A summary of existing information of the im pacts of stream hydromodification on the 1 quality of the Chesapeake Bay is provided in Table 7-1. These studies demonstrate the 2 importance of stream restoration and protection in achieving pollutant reduction in the 3 Chesapeake Bay, particularly for sediment and the P phosphorus that accompanies sediment 4 loading. 5
Table 7-1. Studies quantifying the impact of sedime nt loading from stream hydromodification on 6 Chesapeake Bay water quality 7 Study Findings A Summary Report of Sediment Processes in Chesapeak e Bay and Watershed

, USGS, Water-Resources Investigations Report 03-4123, 2003 Summarizes the impacts and sources of sediment and notes that sediment yield from urbanized areas can remain high after active construction is complete because of increased stream corridor erosion due to altered hydrology Schueler, Thomas, et.al, The Practice of Watershed Protection, Technical Note #119 from Watershed Protection Techniques 3(3):729-734 , Center for Watershed Protection, 2000. Stream enlargement, and the resulting transport of excess sediment, is caused by urban development

U

. S

. Environmental Protection Agency. 2001. Protecting and Restoring America’s Watershed’s: Status, Trends , and Initiatives in Watershed Management, EPA 840-R-00-0 01. http://www.epa.gov/owow/nps/urbanm/pdf/urban_guidan ce .pdf

. Straighten and channelized streams carry more sediments and other pollutants to their receiving waters. Up to 75% of the transported sediment from the Pocomoke watershed on the Eastern Shore of Maryland was found to be erosion from within the stream corridor Gellis et al. Synthesis of U.S. Geological Survey Science for the Chesapeake Bay Ecosystem and Implications f or Environmental Management, Chapter 6: Sources and Transport of Sediment in the Watershed . 2007, U.S. Geological Survey Circular 1316. Sediment sources are throughout the Chesapeake Bay watershed, with more in developed and steep areas

Gellis et al. 2009, Sources, transport, and storage of sediment in the Chesapeake Bay Watershed: U.S. Geological Survey Scientific Investigations Report 2008– 5186 In the Piedmont region, streambank erosion was a major source of sediment in developed Little Conestoga Creek; 30% of sediment from the Mattawoman Watershed on the Coastal Plain (flat land) is from streambanks Devereux et al. Suspended-sediment sources in an ur ban watershed, Northeast Branch Anacostia River, Maryla nd. Hydrological Processes, Accepted 2009. Streambank erosion was the primary source of sediment in the Northeast Branch Anacostia River 8 While the contribution of sediment from streambank Streambank erosion might be a significant 9 source in many streams, the percentage of unstable streams within the Chesapeake Bay 10 watershed is unknown (USGS 2003). 11 The contribution of hydromodification to other poll utants of concern in the Chesapeake Bay is 12 even less well documented. N Nitrogen contribution throughout the watershed is primarilyfrom 13 agricultural, wastewater, and airborne sources. N Nitrogen in its most commonly observed forms 14 is present in very low levels within contributions from hydromodification sources. P Phosphorus 15 on the other hand, given its tendency to become soi l and particulate bound is often present in the 16 legacy sediments, which are significant contributor s to eroding streams. 173/15/20 2

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Chapter 7. Hydromodification 7 

## 2

. Chesapeake Bay Hydromodification Implementation 1 

## Measures 2 In 2007 EPA published a guidance document titled National Management Measures to Control 3 Non-point Source Pollution from Hydromodification (USEPA 2007) whose purpose was to 4 provide background information on nonpoint source p ollution and to offer a variety of solutions 5 for reducing nonpoint source pollution resulting fr om hydromodification. Background 6 information included a discussion of the sources of nonpoint source pollution and mechanisms 7 for transport into the nation’s waters. The guidanc e further presented a series of Management 8 Measures for use on a national scale to directly address th e causative factors for nonpoint source 9 pollution. Management measures as presented in the 2007 document establish performance 10 expectations and where appropriate specific actions that can be taken to prevent or minimize 11 nonpoint source pollution. 12 A series of practices was also described for each m anagement measure. Practices are specific 13 actions taken to achieve, or help achieve aid in the achievement o f a management measure. 14 Practices are often termed best management practice s (BMPs); however, the word best was 15 dropped from the 2007 Hydromodification guidance an d will not be used in this chapter 16 because as the use of the adjective is too subjective. 17
This While this document should not necessarily be considered an a ddendum or follow up to the 18 2007 guidance ; for more information, , EPA encourages the reader to see the earlier guidance for 19 more information

. 20 

### 2.1 General Principles and Goals 21 The purpose of this guidance document is to provide the user with background information on 22 how hydromodification activities affect nutrient an d sediment impacts within the Chesapeake 23 Bay and to provide guidance on a range of practices that can be implemented to reduce the 24 impact of hydromodification activities on bay water quality. While this document focuses on 25 practices that are relevant to the Chesapeake Bay a nd its associated watershed specifically, the 26 information provided herein is also widely relevantwherever hydromodification activities result 27 in degradation of surface waters. 28 While the primary focus of this document is on redu cing loading of sediment, N itrogen , and 29 P hosphorous , it is important to note that there are often nume rous secondary benefits to each 30 specific practice detailed herein. To that this end where appropriate additional information is 31 provided on secondary benefits such as those associ ated with living resources (and 32 complementing the activities suggested in draft rep ort 202(g) of Executive Order 13508). For 33 example bioengineering techniques such as live stak ing and brush mattressing are typically 34 applied to an eroding streambank principally to red uce sediment loading to the associated stream. 35 However, the function of those these practices is based on establishing riparian vegeta tion, which 36 is an important component in improving aquatic riparian habitat. 37 For many hydromodification activities and their ass ociated effects, a close relationship exists to 38 other sections of this guidance series. In such cas es, the reader might be directed to the 39 associated section for additional guidance. For ins tance, increased rate and volume of stormwater 403/15/20 2

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Chapter 7. Hydromodification 8 runoff from urbanizing areas often leads to channel and streambank erosion. In that case, the 1 causative factor of the effect (urbanization) is co vered in the urban section of this document. 2 Because streambank erosion is itself considered a f orm of hydromodification, the effect is 3 described in detail and number of structural practi ces recommended to address the effect within 4 the stream corridor. 5 

### 2.2 Implementation Measures 6 To accomplish the goals set forth above, this docum ent suggests using five implementation 7 measures. The reader might use the measures to addr ess the causative factors that result in 8 sediment and nutrient loading to the Chesapeake Bayassociated with hydromodification 9 activities. 10

11
This document expands on the extensive resources pr ovided in the 2007 document while 12 focusing on the pollutants, sources, and practices considered important to the overall goal of 13 restoring the health of the Chesapeake Bay. Impleme ntation Measures (formerly management 14 measures) presented are either the same or improvedversions of those suggested in the 2007 15 guidance. Where available, information on the appli cation, design and performance of specific 16 practices suitable for use in the Chesapeake Bay ar e provided. To support one of the key steps 17 required by the Executive order 13508 to define next generation tools, a number of practices 18 have been added to this document which exhibit prov en capability to address the nonpoint source 19 issues within the Chesapeake Bay. 20 Implementation Measures Implementation Measure #1 – Protect Streambanks and Shorelines from Erosion Implementation Measure #2 – Control Upland Sources of Sediment and Nutrients at Dams Implementation Measure #3 – Restore In-stream and R iparian Habitat Function Implementation Measure #4 – Reduce Pollutant Source s through Operational and Design Management Implementation Measure #5 – Restore Stream and Shor eline Physical Characteristics3/15/20 2

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Chapter 7. Hydromodification 9 

### 2.2.1 Implementation Measure #1: Protect Streambank s and Shorelines 1 

### from Erosion 2 Implementation Measure: The protection of streambanks and shorelines from e rosion refers to the installation of structural or biological practi ces at or near the land water interface. This measure directly addresses one of the primary contr ibutors of pollution from hydromodification activities. The primary goals of this implementatio n measure are the following:
1. Protect streambank and shoreline features with t he potential to reduce nonpoint source pollution
2. Protect streambanks and shorelines from erosion from uses of either the shorelands or adjacent surface waters
The protection of streambanks and shorelines from eros ion refers to the installation of structural 3 or biological practices at or near the land water i nterface. This measure directly addresses one of 4 the primary contributors of pollution from hydromodification activities. The primary goals of 5 this implementation measure are the following : 6
1. Protect streambank and shoreline features with the pote ntial to reduce nonpoint source 7 pollution. 8
2. Protect streambanks and shorelines from erosion because of uses of eith er the shorelands or 9 adjacent surface waters. 10

2.2.1.1 Existing Practices 11 The National Management Measures to Control Nonpoint So urces Pollution from 12 Hydromodification document (USEPA published by EPA in 2007 ) provides information on the 13 use of the following practices to protect streamban ks and shorelines from erosion: 14

• Breakwaters 15

• Bulkheads and seawalls 16

• Groins 17

• Return Walls 18

2.2.1.2 Multi-Cell Culvert 19 Description 20 Roadway crossing, typically of smaller streams, whe re the main culvert at the stream channel is 21 sized for bankfull discharge and additional culvert s are placed on the floodplain to convey 22 overbank flow up to the design discharge. 23
Application and Purpose 24 The use of a multi-cell culvert distributes stream conveyance during larger storm events across a 25 larger portion of the stream/floodplain cross-secti on than the traditional single culvert system 263/15/20 2

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Chapter 7. Hydromodification 10 resulting in reduced flow velocities and better flo odplain connectivity, In addition the smaller 1 primary culvert can increase flow depths during low flows enabling fish passage. 2 Multi-cell culverts typically consists of a primaryculvert installed inline with the stream channel 3 and sized with a cross-sectional area equivalent to the stream at bankfull discharge. One or more 4 secondary culverts are located at floodplain or bankful elevation at variable loca tions across the 5 road crossing to provide passage of floodflow. Prim ary culvert inverts are often placed below the 6 channel invert to allow water and sediments to pool within the culvert to enable fish passage. 7 The placement and geometry of the primary culvert i s intended to allow the natural transport of 8 sediment in the stream channel and prevent scour of the streambed because of due to flow 9 contraction (Rosgen 1996). The combined capacity of the primary and secondary culverts is the 10 design flow. 11 Multi-cell culverts might not be appropriate for streams that are incised or actively incising 12 streams, exhibit high flow velocities, or streams t hat often carry a heavy debris load (Johnson 13 and Brown 2000). Use of multi-cell culverts in such systems could result in perched culverts and 14 debris jams, Rosgen (1996) type C or E channels mig ht be most appropriate for use of multi-cell 15 culverts (Maryland Waterways Construction Guideline s 2000) 16

Performance 17 Published data on the performance of multi-cell cul verts is primarily limited to fish passage 18 requirements and assessment of appropriate channels systems. Laboratory scale model 19 experiments investigating the scour and flow depth characteristics of multi-cell culverts showed 20 reduction in overall scour pool volume and culvert perching of 52 percent and 55 percent , 21 respectively (Wargo and Weisman 2006). (Wargo 2006)

. 22 Design Guidance and additional info 23 Maryland Department of the Environment Water Manage ment Administration, 2000. 24 Maryland’s Waterway Construction Guidelines at . At 25 http://www.mde.state.md.us/assets/document/wetlands waterways/mgwc.pdf . Accessed 26 February 2010. 27

2.2.1.3 Non-eroding Roadways 28 Description 29 Non-eroding roadways refer to practices that reduce the sediment load to receiving waterbodies 30 from dirt and gravel roads. 31
Application and Purpose 32 The National Management Measures to Control Nonpoint So urces Pollution from 33 Hydromodification document (USEPA published by EPA in 2007 ) contains a chapter on the 34 practice of Non-eroding Roadways. For additional in formation on the appropriate use and 35 application of non-eroding roadways, see the 2007 g uide. 36
In addition to the information contained in the 200 7 guide, the following practices are 37 recommended to reduce the sediment load from dirt a nd gravel roads. 383/15/20 2

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Chapter 7. Hydromodification 11 Driving Surface Aggregate (DSA) 1 DSA is a specific gradation of crushed stone develo ped by the Center for Dirt and Gravel Road 2 Studies specifically for use as a surface wearing c ourse for unpaved roads. DSA achieves 3 sediment reductions by decreasing erosion and trans port of fine material from the road surface. 4 Sandstone- and limestone-derived aggregates are pre ferred. 5 Raising the Road Profile 6 Raising the road profile involves importing materia l to raise the elevation of an unpaved road. It 7 is typically practiced on roads that have become en trenched (lower than surrounding terrain). 8 Raising the elevation of the road is designed to re store natural drainage patterns by eliminating 9 the downslope ditch and providing cover for pipes t o drain the upslope ditch. Removing the 10 downslope ditch will eliminate concentrated flow co nveyed in the ditch and create sheet flow. 11 Raising the road profile Road Profile achieves sediment reduction by controlling and red ucing the 12 volume of road runoff. 13 Raising the road profile involves importing fill ma terial to raise the elevation of the roadway up 14 to the elevation of the surrounding terrain. The ro ad is filled to a sufficient depth as to eliminate 15 the ditch on the downslope side of the road and enc ourage sheet flow. Shale and gravel are the 16 most common fill materials for roads. Other potenti al recycled fill materials include ground 17 glass, waste sand, automobile tires, clean concrete rubble, and the like. 18
Grade Breaks 19 Grade breaks are an intentional increase in road el evation on a downhill grade, which causes 20 water to flow off of the road surface. It is design ed to reduce erosion on the road surface by 21 forcing water into the ditches or surrounding terra in. Erosion of the road surface is reduced by 22 forcing runoff laterally off the road. In some case s, grade breaks are used to force water off the 23 road entirely, serving as an additional drainage ou tlet. Sites where water is not forced off the 24 road entirely convey the water into a roadside ditc h. 25 Drainage Outlets 26 Drainage outlets are designed to capture water flow ing in the roadside ditch and force it to leave 27 the road area. There are two major types of drainag e outlets. Turnouts (also called bleeders or 28 cutouts) outlet water from the downslope road ditch . They usually consist of relatively simple 29 cuts in the downslope road bank to funnel road drai nage away from the road. Drainage that is 30 carried by the upslope road ditch is usually outlet ted under the roadway by the use of a crosspipe 31 (also called culvert, sluice pipe, or tile drain). Installing additional drainage outlets reduces 32 concentrated flow, peak flow discharges and sedimen t transport and delivery from unpaved roads 33 and ditches into streams, and can increase infiltra tion. It does not affect sediment generation 34 from the road surface or deliver in the upslope dit ch; thus, all data on sediment reductions in this 35 document is for a downslope ditch only, unless othe rwise noted. Drainage outlets are to be 36 placed in locations that have the least likelihood of reaching streams. If a newly added outlet 37 conveys sediment to the stream, little, if any, sed iment reductions will be obtained. 38
Berm Removal 39 A berm is a mound of earthern material that runs parallel to the road on the downslope side. 40 Berms can be formed by maintenance practices and ro ad erosion that lowers the road elevation 413/15/20 2

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Chapter 7. Hydromodification 12 over time. In many cases, the berm is unnecessary a nd creates a ditch on the downslope side of 1 the road. The berm can be removed to encourage shee t flow into surrounding land instead of 2 concentrated flow in an unnecessary ditch. Restorin g sheet flow results in decreased runoff and 3 sediment transport along the roadway, increase infi ltration, and reduced maintenance associated 4 with the road drainage system. 5 Efficiency Data 6 The following total suspended solids (TSS) reductio n efficiencies are estimated for each practice. 7 Technique TSS effectiveness estimate Limestone* 50% Driving Surface Aggregate Sandstone 55% Raising the Road Profile 45% Grade Breaks 30% Additional Drainage Outlet 15% Berm Removal 35% 8 Total nitrogen (TN) and total phosphorus ( Total p hosphorous ( TP) removal is minimal with dirt 9 and gravel road sediment control. One reason is tha t dirt and gravel roads are not fertilized. The 10 other is that the environmental benefit association with dirt roads is such that nitrogen ( N ) and 11 p hosphorus ( P ) reductions are not anticipated, nutrient reduction s are not a component of the 12 average function of dirt and gravel roads. If N and P reductions are associated with dirt and 13 gravel roads, they should track sediment reductions should be tracked

. 14 Design Guidance and additional info 15 For additional information on non-eroding roadways, see the following sources: 16 Controlling Nonpoint Source Runoff Pollution from R oads, Highways, and Bridges 17 http://www.epa.gov/owow/nps/roads.html 18 Erosion, Sediment, and Runoff Control for Roads and Highways 19 http://www.epa.gov/owow/nps/education/runoff.html 20 Gravel Roads: Maintenance and Design Manual—the purpose of the manual is to provide clear 21 and helpful information for doing a better job of m aintaining gravel roads. The manual is 22 designed for the benefit of elected officials, mang ers, and grader operators who are responsible 23 for designing and maintaining gravel roads. http://www.epa.gov/owow/nps/gravelroads 24 Low-Volume Roads Engineering Best Management Practi ces Field Guide 25 http://zietlow.com/manual/gk1/web.doc 26 Massachusetts Unpaved Roads BMP Manual 27 http://www.berkshireplanning.org/download/dirt_road s.pdf 28 Planning Considerations for Roads, Highways, and Br idges 29 http://www.epa.gov/owow/nps/education/planroad.html 303/15/20 2

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Chapter 7. Hydromodification 13 Pollution Control Programs for Roads, Highways, and Bridges 1 http://www.epa.gov/owow/nps/education/control.html 2
Recommended Practices Manual: A Guideline for Maint enance and Service of Unpaved Roads 3 http://www.epa.gov/owow/nps/unpavedroads.html 4
The Road Maintenance Video Set is a five-part video series developed for the U.S. Department 5 of Agriculture

–(USDA) Forest Service (USDA-FS) equipment operators that focuses on 6 environmentally sensitive ways of maintaining low v olume roads. 7 http://www.epa.gov/owow/nps/maint_videoset.html 8

2.2.1.4 Riprap 9 Description 10 Riprap is a layer of appropriately sized stones des igned to protect and stabilize areas subject to 11 erosion, slopes subject to seepage, or areas with p oor soil structure. 12
Application and Purpose 13 The National Management Measures to Control Nonpoint So urces Pollution from 14 Hydromodification document (USEPA published by EPA in 2007 ) contains a chapter on the 15 practice of Riprap. At the time of this writing, no additional information is provided pertaining to 16 this practice. For information on the appropriate u se and application for riprap, see the 2007 17 guide. 18

Cost Data 19 Riprap costs vary depending on the class of riprap, the location of the quarry, and installation 20 practices. Prices typically range from $40 to $70 p er ton. 21

2.2.1.5 Toe Protection 22 Description 23 Toe protection refers to the installation of erosio n resistant material, typically stone, near and at 24 the water line along shorelines and streams to redu ce wave reflection and scour of the land water 25 interface. 26
Application and Purpose 27 The purpose of toe protection is to dissipate wave and scour energy at the land water interface of 28 and therefore reduce shoreline and streambank erosi on. 29
The National Management Measures to Control Nonpoint So urces Pollution from 30 Hydromodification document (USEPA published by EPA in 2007 ) provides information on the use 31 of tow protection to reduce shoreline erosion. Whil e the installation techniques and methods differ 32 slightly where toe protection is used to reduce str eambank erosion the practice is principally the 33
same. 343/15/20 2

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Chapter 7. Hydromodification 14 Efficiency Data 1 Efficiency data on toe protection in streambanks is limited. However, recent research projects 2 have shown reduced loss of streambank where toe pro tection is implemented on eroding 3 channels. A modeling study in the Lake Tahoe basin using the Bank-Stability and Toe-Erosion 4 Model (BSTEM) predicted that the application of a 1 .0-m-high rock toe protection would reduce 5 bank erosion by 69–100 percent (Simon et al. 2009). It was further noted that only 14 percent of 6 the sediment loss in the streambank of the studied reach was from the toe region, the remaining 7 sediment loss resulted from mass wasting of the ove rlying streambank indicating the importance 8 of the land water interface in overall stream sedim ent dynamics. 9


### 2.2.2 Implementation Measure #2: Control Upland Sou rces of Sediment and 10 

### Nutrients at Dams 11 Implementation Measure: The control of upland sources of nonpoint source po llutants at dams, as well as other hydromodification facilities, refe rs to the active implementation of pollutant control techniques and practices that minimize the source generation and reduce the transport of sediments and nutrients into the Chesapeake Bay andits watershed. This implementation measure was well described in the 2007 guidance doc ument (formerly titled Erosion and Sediment Control for Construction of New Dams and M aintenance of Existing Dams ). The goals of this implementation measure are 1. Reduce the generation of sediment and nutrients during and after construction 2. Retain eroded sediment and nutrients on-site 3. Apply nutrients at rates necessary to establish and maintain vegetation without causing significant nutrient runoff to surface waters The control of upland sources of nonpoint source pollutants at dams, as well as other 12 hydromodification facilities, refers to the active implementation of pollutant control techniques 13 and practices which minimize the source generation reduce the transport of sediments and 14 nutrients into the Chesapeake bay and its watershed. This Implementation Measure was well 15 described within the 2007 guidance document ( formerly titled Erosion and Sediment Control for 16 Construction of New Dams and Maintenance of Existin g Dams). The goals of this 17 i mplement ation m easure are 18
1. Reduce the generation of sediment and nutrients dur ing and after construction

. 19
2. R etain erode d sediment and nutrients onsite. 20
3. Apply nutrients at rates necessary to establish and maintain vegetation without causing 21 significant nutri ent runoff to surface waters. 22

2.2.2.1 Existing Practices 23 The National Management Measures to Control Nonpoint So urces Pollution from 24 Hydromodification Hydromodification document (USEPA published by EPA in 2007 ) provides 253/15/20 2

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Chapter 7. Hydromodification 15 information on using the following practices to con trol upland sources of sediment and nutrients 1 at dams: 2

• Check Dams 3

• Coconut Fiber Roll 4

• Construction Runoff Intercepts 5

• Construction Management 6

• Erosion Control Blankets 7

• Locate Potential Land Disturbing Activities Away fr om Critical Areas 8

• Mulching 9

• Preserve Onsite Vegetation 10

• Phase Construction 11

• Retaining walls 12

• Revegetate 13

• Project Scheduling 14

• Sediment Basin/ Rock Dams 15

• Sediment fences 16

• Sediment traps 17

• Seeding 18

• Site Fingerprinting 19

• Sodding 20

• Soil Protection 21

• Surface Roughening 22

• Training ESC 23

• Wildflower cover 24


### 2.2.3 Implementation Measure #3: Restore In-stream and Riparian Habitat 25 

### Function 26 Implementation Measure: The restoration of in-stream and riparian habitat f unction refers to the direct implementation of practices which addres s functions of the aquatic environment. Because the practices recommended as part of this i mplementation measure often do not address the causative factors behind habitat degradation, o ther implementation measures described in this document should be considered for implementation. T his implementation measure was well described in the 2007 guidance document (formerly t itled Protection of Surface Watery Quality and In-stream and Riparian Habitat ). The primary goal of this implementation measure is 1. Provide for safe passage of fish and other aquat ic species upstream or downstream of dams and other structures3/15/20 2

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Chapter 7. Hydromodification 16 The r estoration of in

- stream and riparian habitat function refe rs to the direct implementation of 1 practices which address functions of the aquatic environment. Since the practices recom men ded 2 as part of this implementation measure often do notaddress the causative factors behind 3 degradation of habitat, other implementation measur es described in this guidance document 4 should be considered for implementation

. This Implementation Measure was well described 5 within the 2007 guidance document (formerly titled Protection of Surface Watery Quality and 6 In

- stream and Riparian Habitat ). The primary goal of this implementation measure is : 7
1. Provide for safe passage of fish and other aquatic species up stream or downstream of dams 8 and other structures. 9

2.2.3.1 Existing Practices 10 The National Management Measures to Control Nonpoint So urces Pollution from 11 Hydromodification document (USEPA published by EPA in 2007 ) provides information on using 12 the following practices restore in-stream and ripar ian habitat function: 13

• Behavioral Barriers 14

• Collection Systems 15

• Fish Ladders 16

• Fish Lifts 17

• Physical Barriers 18

• Transfer of Fish Runs 19 Note: Certain other practices as described in otherchapters of this document might be 20 appropriate for use in meeting the goals of this im plementation measure. For instance the Legacy 21 effects of Dams and Dam Removal practice is include d in the Implementation Measure 5: 22 Restore Stream and Shoreline Physical Characteristi cs. 23
2.2.3.2 Shoreline Sensitivity Assessment 24 Description 25 Shoreline Sensitivity Assessments are methodologies that apply to shoreline areas and are used 26 to evaluate, classify and assess stability and eros ion vulnerabilities in various types of lakes, 27 reservoirs, estuaries, and coasts. 28
Application and Purpose 29 Langendoen et al. (2009) Langendoen (2009) found that restoration projects could benefit from 30 using proven models of stream and riparian processe s to guide restoration design and to evaluate 31 indicators of ecological integrity. The USDA has de veloped two such models: the channel 32 evolution computer model (CONCEPTS) and the Riparia n Ecosystem Management Model 33 (REMM). 343/15/20 2

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Chapter 7. Hydromodification 17 Efficiency Data 1 The physical process modules of the channel evoluti on model CONCEPTS and the riparian 2 ecosystem model REMM have been integrated to create a comprehensive stream-riparian 3 corridor model that will be used to evaluate the ef fects of riparian buffer systems on in-stream 4 environmental resources (Langendoen et al. 2009). ( Langendoen 2009). The models have been 5 integrated to evaluate the impact of edge-of-field and riparian conservation measures on stream 6 morphology and water quality. The capability of REM M to dynamically simulate streambank 7 hydrology and plant growth has been used to study t he effectiveness of a deciduous tree stand 8 and an eastern gamagrass buffer in controlling the stability of a streambank of an incised stream 9 in northern Mississippi. 10

2.2.3.3 Establish and Protect Stream Buffers 11 Description 12 Stream buffers can provide cost-effective, long-ter m pollutant removal without having to 13 construct and maintain structural controls. Specifi c stream buffer practices include establishing a 14 stream buffer ordinance, developing vegetative and use strategies within management zones, 15 establishing provisions for stream buffer crossings , integration of structural runoff management 16 practices where appropriate and developing stream b uffer education and awareness programs. 17
Application and Purpose 18 Establishing and protecting these areas is importan t to water quality protection. Land acquisition 19 programs help to preserve areas considered critical to maintaining surface water quality. Stream 20 buffers can also protect and maintain near-stream v egetation that attenuates the release of 21 sediment into stream channels. Stream buffers shoul d be protected and preserved as a 22 conservation area because they provide many importa nt functions and benefits, including the 23 following: 24

• Providing a right-of-way for lateral movement 25

• Conveying floodwaters 26

• Protecting streambanks from erosion 27

• Treating runoff and reducing drainage problems fromadjacent areas 28

• Providing nesting areas and other wildlife habitat functions 29

• Mitigating stream warming 30

• Protecting wetlands 31

• Providing recreational opportunities and aesthetic benefits 32

• Increasing adjacent property values 33
Efficiency Data 34 The biennial National Water Quality Inventory surve ys shows no reduction in the percentage of 35 degraded miles of streams since the early 1990s des pite an exponential increase in river 36 restoration projects to improve water quality, enha nce in-stream habitat and manage the riparian 37
zone (Langendoen et al. 2009). (Langendoen 2009). This might suggest that many river 383/15/20 2

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Chapter 7. Hydromodification 18 restoration projects fail to achieve their objectiv es. This was found to be partly due to a lack of 1 understanding of the dynamics of the degraded river ine system and its interaction with the 2 riparian zone. Vegetative riparian conservation mea sures are commonly used to stabilize failing 3 streambanks. The shear strength of bank soils is gr eatly affected by the degree of saturation of 4 the soils and root reinforcement provided by ripari an vegetation. An integrated model was used 5 to study the effectiveness of woody and herbaceous riparian buffers in controlling streambank 6 erosion of an incised stream in northern Mississipp i. Comparison of model results with 7 observations showed that pore-water pressures are a ccurately predicted in the upper part of the 8 streambank, away from the groundwater table. Simula ted pore-water pressures deviate from 9 those observed lower in the streambank near the phr eatic surface. These discrepancies are mainly 10 caused by differences in the simulated location of the phreatic surface and simulated 11 evapotranspiration in case of the woody buffer. The modeling exercise further showed that a 12 coarse rooting system, e.g., as provided by trees, significantly reduced bank erosion rates for this 13 deeply incised stream. 14 The impact of different management of similar ripar ian land uses was studied in two pasture 15 subreaches by Zaimes et al. (2008), Zaimes et al

. (2006) , who found that total streambank soil 16 loss can be estimated by using magnitude of bank er osion, soil bulk density, and severely eroded 17 bank area. Significant seasonal and yearly differen ces in magnitude of bank erosion and total soil 18 loss were partially attributed to differences in pr ecipitation and associated discharges. Riparian 19 forest buffers had significantly lower magnitude of streambank erosion and total soil loss than 20 the other two riparian land uses. Establishment of riparian forest buffers along all of the 21 nonbuffered subreaches would have reduced streamban k soil loss by an estimated 77 to 97 22 percent, significantly decreasing sediment in the s tream. The pasture with cattle had consistently 23 higher magnitudes of bank erosion than those for th e pasture with horses for the entire study 24 period. The pasture with cattle was also the only s ubreach to show an increase in eroding stream 25 length ( 3 3 percent) and eroding area (10 percent) from 1998 to 2002. Riparian vegetation and 26 land use are an integral part of streambank erosion , but high precipitation levels and associated 27 high discharges can also influence the erosion proc ess. Differences in the magnitude of bank 28 erosion, severely eroded bank lengths and areas, an d soil losses throughout this study are 29 partially attributable to differences in precipitat ion that were associated with the occurrence of 30 substantial discharge events. Other processes such freeze and thaw events and season, which 31 impacted the density of the vegetation cover of the watershed, were also implicated. The 32 variation in soil losses from streambank erosion ov er the entire study period also suggest that a 33 dataset of many years is needed to get a good estim ate of bank erosion contributions to stream 34 sediment load. One-year datasets can be misleading in estimating the long term contributions of 35 bank erosion to stream sediment loads. 36 A partnership involving more than a dozen organizat ions, agencies and businesses joined forces 37 to construct a 800-foot living shoreline that rebuilt the barrier between the creek and the cove 38 with natural materials, which was then planted with native plants to provide more stability 39 (Blankenship 2009) (Alliance for the Chesapeake Bay, Blankenship, ed., November 2009). The 40 project relied on volunteers and multiple funders a nd was the first project in the Chesapeake Bay 41 that involved the Corporate Wetland Restoration Partnership, which brings together government 42 on environmental projects. This type of restoration project was envisioned in the draft habitat 43 report that responded to President Barack Obama’s C hesapeake Bay Executive Order of May of 443/15/20 2

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Chapter 7. Hydromodification 19 2009. The report calls for using partnerships to bu ild strategically placed “largescale, 1 multifaceted restoration [projects] targeted at imp roving living resources.” 2 Besides the living shoreline, curved rock structure s were built at both ends of the cove to protect 3 it from waves and to trap sand that will serve as b each habitat. The project included the 4 construction of an oyster reef, which serves as hab itat and buffers the shoreline from waves. 5 Shallow water habitats, which had largely eroded aw ay, were rebuilt and planted with marsh 6 grasses. Reestablishing shallow water habitat, incl uding oyster beds and mussel beds, will serve 7 as foraging grounds for sea ducks, which should kee p Hail Creek as one of the top five 8 waterfowl habitats for years to come. 9 Langendoen et al. (2009) Langendoen (2009) found that restoration projects could benefit from 10 using proven models of stream and riparian processe s to guide restoration design and to evaluate 11 indicators of ecological integrity. The USDA has de veloped two such models: CONCEPTS and 12 REMM. Those models have been integrated to evaluate the impact of edge-of-field and riparian 13 conservation measures on stream morphology and wate r quality. The physical process modules 14 of the channel evolution model CONCEPTS and the rip arian ecosystem model REMM have 15 been integrated to create a comprehensive, stream-r iparian corridor model that will be used to 16 evaluate the effects of riparian buffer systems on in-stream environmental resources. The 17 capability of REMM to dynamically simulate streamba nk hydrology and plant growth has been 18 used to study the effectiveness of a deciduous tree stand and an eastern gamagrass buffer in 19 controlling the stability of a streambank of an inc ised stream in northern Mississippi. 20

Cost Data 21 A study of cost-effectiveness analysis of vegetativ e filter strips and in-stream half-logs as tools 22 for recovering scores on a fish index of biotic int egrity (IBI) in the upper Wabash River in 23 Indiana provided baseline data and a framework for planning and determining the cost of stream 24 restoration (Frimpong et al. 2006). (Frim pong et al

. 2006). The authors found that costs per unit 25 increase in IBI score with vegetative filter strips as the method of restoring stream health 26 decreases with increasing stream order and decreasi ng recovery time and that vegetative filter 27 strips is likely a useful method, given cost consid erations, for recovering lost IBI scores in an 28 agricultural watershed. Three assumptions were made about recovery time for IBI scores (5, 15, 29 and 30 years) and social discount rates (1, 3, and 5 percent), which were tested for sensitivity of 30 the estimated cost-effectiveness ratios. The effect iveness of vegetative filter strips was estimated 31 using fish IBIs and riparian forest cover from 49 first-order to fifth-order stream reaches. Half32 log structures had been installed for approximately2 years in the watershed before the study and 33 provided a basis for estimates of cost and maintena nce. Cost-effectiveness ratios for vegetated 34 filter strips decreased from $387 to $277 per 100 m eters for a 1 percent increase in IBI scores 35 from first- to fifth-order streams with 3 percent d iscount and 30-year recovery. This cost 36 weighted by proportion of stream orders was $360 pe r 110 meters. On the basis of installation 37 costs and an assumption of equal recovery rates, ha lf-logs were two-thirds to one-half as cost38 effective as vegetative filter strips. Half-logs wo uld be a cost-effective supplement to filter strips 39 in low-order streams if they can be proven to recov er IBI scores faster than using filter strips 40 alone. 413/15/20 2

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Chapter 7. Hydromodification 20 Design Guidance and additional info 1 Maryland Department of the Environment Water Manage ment Administration, 2000. Maryland’s 2 Waterway Construction Guidelines at . A t 3 http://www.mde.state.md.us/assets/document/wetlands waterways/mgwc.pdf . Accessed 4 February 2010. 5

2.2.3.4 Riparian Improvements 6 Description 7 Riparian improvements are strategies used to restor e or maintain aquatic and riparian habitat 8 around reservoir impoundments or along the waterway s both upstream of and downstream from 9 dams and include reducing sediment loading in the d ownstream watershed, improving riparian 10 vegetation, eliminating barriers to fish migration, providing greater in-stream and riparian habitat 11 diversity and reducing flow-related effects on dams

. 12
Application and Purpose 13 Maintaining and improving riparian areas upstream o f and downstream from dams is an 14 important consideration. Riparian improvements migh t be necessary along smaller-order streams 15 if their ability to detain and absorb floodwater an d stormwater has been impaired—often the 16 result of removing forest cover or increasing water shed imperviousness. Cumulative effects on 17 riparian areas of smaller streams include increaseddischarge volumes and velocities of water, 18 which then result in more severe downstream floodin g and increased storm damage or 19 maintenance to existing structures, including dams. Information on techniques to mitigate effects 20 on smaller streams can is also in the Urban Section of this guidance (Chapter 3). 21 Design Guidance and additional info 22 The Iowa Department of Natural Resources (no date) recommends that the property owner or 23 developer estimate the amount of time, materials, e quipment, and labor necessary to complete 24 the work as compared to those personally available. This is a subjective decision based on time, 25 knowledge, and resource constraints. 26 a. Construction activities should be conducted dur ing periods of low flow. 27 b. Construction equipment, activities, and materia ls should be kept out of the water to the 28 maximum extent possible. 29 c. All construction debris should be disposed of o n land in such a manner that it cannot 30 enter a waterway or wetland. 31 d. Equipment for handling and conveying materials during construction should be operated 32 to prevent dumping or spilling the material into wa terbodies, streams, or wetlands. 33 e. Care should be taken to prevent any petroleum p roducts, chemicals, or other deleterious 34 materials from entering waterbodies, streams, or we tlands. 35 f. Clearing of vegetation, including trees locatedin or immediately adjacent to waters of the 36 state, should be limited to that which is absolutel y necessary for construction of the 373/15/20 2

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Chapter 7. Hydromodification 21 project. All vegetative clearing material shall be removed to an upland, non-wetland 1 disposal site. 2 Each of the methods described in the manual require s observation and maintenance of the 3 streambank erosion control practices over time. Obs ervations should be made regularly before 4 and after major stream flow events. Maintenance act ivities should include the following: 5

• Remove any debris that becomes entangled in the ero sion control material and could 6 damage the bank materials. 7

• Replace missing or damaged erosion control material s during times of low stream flow. 8

• Apply fertilizer to plant materials to enhance thei r growth each year. 9

• Apply fertilizer and weed control to buffer strip v egetation. 10

• Restrict livestock from steep banks and the areas c ontaining the erosion control measures. 11 Riparian Buffers 12 Riparian buffers are described in Chapter 5 of this document. 13

2.2.3.5 Vegetated Buffers 14 Description 15 Vegetated buffers are a naturally occurring, compos ed of vegetative areas that provide physical 16 separation between a waterbody and adjacent land us es. 17
Application and Purpose 18 Vegetated buffers remove nutrients and other pollut ants from runoff, trap sediments, and shade 19 the waterbody to optimize light and temperature con ditions for aquatic plants and animals. 20 Efficiency Data 21 Protection or restoration of modest-sized patches o f living shoreline can provide adequate prime 22 waterfowl habitat (Blankenship 2009). (Alliance for the Chesapeake Bay, Blankenship, ed., 23 November 2009). Hail Creek, a tiny waterway at the tip of a penins ula that is separated by a 24 narrow swath of land from the Chester River, is sho rter than a half-mile long, but despite its 25 diminutive size, the creek and its surrounding mars hes, part of the Eastern Neck National 26 Wildlife Refuge, are one of the top five waterfowl habitats in Maryland, with large 27 concentrations of bufflehead and scaup, as well as black ducks, Canada geese, and other species. 28 The creek contains about 100 acres of underwater gr asses, in contrast with nearby areas where 29 grasses have been declining. Those habitats have fa ced increasing danger in recent years from 30 rising water levels that have been eating away at a narrow barrier of land that separates the 31 upstream end of the creek from Hail Cove along the Chester River. If breached, the sheltered 32 creek habitats and adjoining wetlands would suddenl y be subjected to highly erosive waves. 33 Besides the living shoreline, curved rock structure s were built at both ends of the cove to protect 34 it from waves and to trap sand that will serve as b each habitat. The project included constructing 35 an oyster reef, which serves as habitat and buffers the shoreline from waves. Shallow water 36 habitats, which had largely eroded away, were rebui lt and planted with marsh grasses. 373/15/20 2

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Chapter 7. Hydromodification 22 Reestablishing shallow water habitat, including oys ter beds and mussel beds, will serve as 1 foraging grounds for sea ducks, which should keep H ail Creek as one of the top five waterfowl 2 habitats for years to come. 3

Cost Data 4 A partnership involving more than a dozen organizat ions, agencies and businesses joined forces 5 to construct a 800-foot living shoreline that rebuilt the barrier between the creek and the cove 6 with natural materials, which was then planted with native plants to provide more stability. The 7 project relied on volunteers and multiple funders a nd was the first project in the Chesapeake that 8 involved the Corporate Wetland Restoration Partners hip, which brings together government on 9 environmental projects. This type of restoration pr oject was envisioned in the draft habitat report 10 that responded to President Barack Obama’s Executiv e Order of May 2009 that calls for using 11 partnerships to build strategically placed “largesc ale, multifaceted restoration [projects] targeted 12 at improving living resources.” 13
2.2.3.6 Vegetated Filter Strips 14 Description 15 Vegetated filter strips are low-gradient vegetated areas that filter overland sheet flow. Runoff 16 must be evenly distributed across the filter strip and channelized flows decrease their 17 effectiveness. 18
Application and Purpose 19 Vegetated filter strips should have relatively low slopes and adequate length to provide optimal 20 sediment control and should be planted with erosion -resistant plant species. The main factors that 21 influence the removal efficiency are the vegetation type, soil infiltration rate, and flow depth and 22 travel time. These factors are dependent on the con tributing drainage area, slope of strip, degree 23 and type of vegetative cover, and strip length. Mai ntenance requirements for vegetated filter 24 strips include sediment removal and inspections to ensure that dense, vigorous vegetation is 25 established and concentrated flows do not occur. 26 Efficiency Data 27 A study of cost-effectiveness analysis of vegetativ e filter strips and in-stream half-logs as tools 28 for recovering scores on a fish IBI in the upper Wabash River in Indiana provided baseline data 29 and a framework for planning and determining the co st of stream restoration (Frimpong et al. 30 2006). (Frimpong et al

. 2006). Three assumptions were made about recovery time fo r IBI scores 31 (5, 15, and 30 years) and social discount rates (1, 3, and 5 percent), which were tested for 32 sensitivity of the estimated cost-effectiveness rat ios. The effectiveness of vegetative filter strips 33 was estimated using fish IBIs and riparian forest c over from 49 first-order to fifth-order stream 34 reaches. Half-log structures had been installed for approximately two years in the watershed 35 before the study and provided a basis for estimates of cost and maintenance. 36

Cost Data 37 Frimpong et al. (2006) ( 2006 ) found that costs per unit increase in IBI score wi th vegetative filter 38 strips as the method of restoring stream health dec reases with increasing stream order and 393/15/20 2

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Chapter 7. Hydromodification 23 decreasing recovery time and that vegetative filterstrips is likely a useful method, given cost 1 considerations, for recovering lost IBI scores in a n agricultural watershed. Cost-effectiveness 2 ratios for vegetated filter strips decreased from $ 387 to $277 per 100 meters for a 1 percent 3 increase in IBI scores from first- to fifth order s treams with 3 percent discount and 30-year 4 recovery. This cost weighted by proportion of strea m orders was $360 per 110 meters. Based on 5 installation costs and an assumption of equal recov ery rates, half-logs were two-thirds to one-half 6 as cost-effective as vegetative filter strips. Half -logs would be a cost-effective supplement to 7 filter strips in low order streams if they can be p roven to recover IBI scores faster than using 8 filter strips alone. 9


### 2.2.4 Implementation Measure #4: Reduce Pollutant S ources through 10 

### Operational and Design Management 11 Implementation Measure: Reduction of pollutant sources through operational and design management of dams refers to the design and managem ent of dams so as to minimize the source generation and reduce the transport of sediments an d nutrients into the Chesapeake Bay and its watershed. This implementation measure was well des cribed in the 2007 guidance document (formerly titled Erosion and Sediment Control for Construction of Ne w Dams and Maintenance of Existing Dams ). The goals of this implementation measure are 1. Reduce pollutant generation and impact on living resources through programmatic dam management 2. Design structures to limit pollutant generation Reduction of pollutant sources through operational and design management of dams refers to the 12 design and management of dams so that minimizethe source generation reduce the transport of 13 sediments and nutrients into the Chesapeake B ay and its watershed. This Implementation 14 Measure was well described within the 2007 guidance document (formerly titled Erosion and 15 Sediment Control for Construction of New Dams and M aintenance of Existing Dams). The goals 16 of this implementation measure are 17
1. Reduce pollutant generation and impact on living resources th ough programmatic dam 18 management. 19
2. Design structures to limit pollutant generation 20

2.2.4.1 Existing Practices 21 The National Management Measures to Control Nonpoint So urces Pollution from 22 Hydromodification document (USEPA published by EPA in 2007 ) provides information on using 23 the following practices to reduce pollutant sources through design and operational management: 243/15/20 2

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Chapter 7. Hydromodification 24 2.2.4.2 Advanced Hydroelectric Turbines 1 Description 2 Advanced hydroelectric turbines are the result of e ngineering studies of how the hydraulic 3 components interact with biota and optimization of turbine operations designed to reduce effects 4 on juvenile fish passing through the turbine as it operates. 5 Application and Purpose 6 Most research on advanced hydroelectric turbines ha s been conducted by electric power 7 producers in the western United States. Improving t he survival of juvenile fish by encouraging 8 development of low impact turbines is also being pu rsued on a national scale by the U.S. 9 Department of Energy and the U

. S

. Army Corps of Engineers. Research includes biologi cal 10 studies of turbine passage at field sites and hydra ulic model investigations leading to innovative 11 concepts for turbine design that will have environm ental benefits and maintain efficient electrical 12 generation. 13 Efficiency Data 14 Previous field studies have shown that improvements in the design of turbines have increased the 15 survival of juvenile fish and researchers continue to examine the causes and extent of injuries 16 from turbine systems, as well as the significance o f indirect mortality and the effects of turbine 17 passage on adult fish. Ongoing research is continui ng to assess improvements in turbine design 18 and operation as well as modeling to assess turbine -passage survival. 19

2.2.4.3 Flow Augmentation 20 Description 21 Flow augmentation is the term used to describe oper ational procedures such as flow regulation, 22 flood releases, or fluctuating flow releases that a ll have the potential for detrimental impacts on 23 downstream aquatic and riparian habitat. Several op tions exist for creating minimum flows in the 24 tailwaters below dams. Sluicing is the practice of releasing water through the sluice gate rather 25 than through the turbines. For portions of the wate rway immediately below the dam, the steady 26 release of water by sluicing provides minimum flows with the least amount of water expenditure. 27 Turbine pulsing is a practice involving the release of water through the turbines at regular 28 intervals to improve minimum flows. In the absence of turbine pulsing, water is released from 29 large hydropower dams only when the turbines are op erating, which is typically when the 30 demand for power is high. 31
Application and Purpose 32 The downstream impacts that can be mitigated throug h the use of flow augmentation are highly 33 variable as each impounded system is unique. The lo cation of a dam within a river system, its 34 age, depth and surface area, the hydraulic residenc e time, the regional climate, operation of the 35 dam, and chemistry of the inflowing waters all infl uence how impoundments affects downstream 36 water quality. Hydropower producers are faced with two environmental problems that can affect 37 the water quality in areas downstream from dams (i. e., tailwaters). These are low concentrations 38 of dissolved oxygen in the water released through t he dam during generation and dry riverbeds 393/15/20 2

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Chapter 7. Hydromodification 25 that result when hydropower generation is shut off. The selection of any particular technique as 1 the most cost-effective is site-specific and depend s on several factors including adequate 2 performance to achieve the desired in-stream and ri parian habitat characteristic, compatibility 3 with other requirements for operation of the hydrop ower facility, availability of materials, and 4 cost. 5 Efficiency Data 6 Numerous studies have examined the effects of flow regulation on water quantity and quality by 7 comparing an impounded system with an adjacent unim pounded system. Mitigation techniques 8 to improve ecosystem health downstream of impoundme nts rely on the restoration of a more 9 natural flow regime by creating and implementing si te-specific dam management plans. 10 A study by Ahearn et al. (2005) Ahern (2005) examined the effects of flow regulation on water 11 quantity and quality by comparing an impounded syst em with an adjacent unimpounded system 12 in California. The study found that a strong season al cycle for total suspended solids, NO 3 -N, 13 TN total nitrogen , PO 4 -P, TP total phosphorus , dissolved silicon, specific conductivity and flow 14 into reservoirs in the lower Mokelumne River was at tenuated by physical and chemical 15 fluctuations creating a weak seasonal pattern. Diss olved silicon and total suspended solids were 16 the two constituents most efficiently sequestered b y the reservoirs. While the reservoirs acted as 17 traps for most constituents, NO 3 -N and PO4-P were produced during the drier years o f the study, 18 2001 and 2002. In contrast, the unimpounded referen ce reach in the Cosumnes River was an 19 annual source for all constituents measured. The Co sumnes delivers its highest NO 3 -N 20 concentrations during the winter months (December–A pril), while peak concentrations in the 21 Mokelumne occur during the snowmelt (May–July) and baseflow (August–November) seasons. 22 Because of downstream N-limitation, this temporal s hift in NO3-N export might be contributing 23 to accelerated algal growth in the reach immediatel y downstream and eventually to algal biomass 24 loading to the downstream Sacramento–San Joaquin De lta. 25 In 2003 the Housatonic Valley Association (HVA) partnered with The Massachusetts Riverways 26 Program (in the Department of Fish & Game) to begin measuring streamflow on several rivers 27 below recreational reservoirs. The measurements ind icated unnatural variations in streamflow at 28 several sites that are detrimental to downstream aq uatic life and habitat. A more naturalflow 29 regime is being reestablished in these streams to i mprove their ecological condition. The HVA 30 has been meeting with Conservation Commissions, Lak e Associations, and other stakeholders to 31 develop guidelines for managing flows out of reserv oirs. The goal is to improve ecosystem 32 health downstream of impoundments through the resto ration of a more natural flow regime by 33 creating site-specific dam management plans in the form of monthly flow recommendations 34 using a methodology jointly developed by the U.S. G eological Survey (USGS) and the 35 Massachusetts Department of Conservation and Recrea tion (DCR). The long-term goal is to 36 develop guidance for Conservation Commissions throu ghout the Commonwealth to help them 37 craft Orders of Conditions for dam projects that in clude specific requirements to provide a year38 round flow regime appropriate to the natural variab ility of the ecosystem downstream of the 39 impoundment. 403/15/20 2

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Chapter 7. Hydromodification 26 Cost Data 1 Since the early 1990s, the Tennessee Valley Authori ty (TVA) has spent about $60 million to 2 address dissolved oxygen problems, including the in stallation of equipment to increase dissolved 3 oxygen concentrations below 16 dams and operational changes and installation of additional 4 equipment to ensure minimum water flows through all its dams. TVA has since completed a 5 second round of improvements by installing or enhan cing oxygen systems at nine projects and 6 two new autoventing turbines have been installed atthe Boone Dam. The additional oxygenation 7 capacity will help offset the increased oxygen dema nds associated with delaying the seasonal 8 drawdown of TVA reservoirs. 9

References 10 Ahearn, D.S., R. Sheibley and R. Dalhlgren. Effects of River Regulation on water QWuality in 11 the Lower Mokelumne River, California. In River Res. Applic. 21: 651

– 670 (2005). 12 Published online 8 June 2005 in Wiley InterScience (www.interscience.wiley.com). DOI: 13 10.1002/rra.853 14 Tennessee Valley Authority, No Date. Tailwater Improvements: Improving Water Qualit y Below 15 TVA Hydropower Dams 16

2.2.4.4 Selective Withdrawal 17 Description 18 Selective withdrawal from a reservoir describes the use of intake structures on reservoirs d ams 19 that are capable of releasing waters from specific locations within a stratified of different 20 temperatures to provide cooler or warmer water column to address temperatures downstream 21 water quality objectives. at times that are critical for other in

- streamresources

. 22
Application and Purpose 23 Selective withdrawal Temperature control in reservoir releases depends on the volume of wat er 24 storage in the reservoir, the timing of the release relative to storage time, and the level from 25 which the water is withdrawn. Selective withdrawal takes advantage of the phenome non of 26 reservoir stratification, in which the water column exhibits various quality characteristics 27 respective to water depth. Multilevel intake devices in storage reservoirs all ow selective 28 withdrawal of water based on temperature , andDO levels or other stratified water quality 29 characteristics . These can be particularly useful in stratified re servoirs so that they can be 30 operated to meet downstream water quality temperature objectives such as to enhance a cold

31 water or warm

- water fishery or to maintain downstream temperature conditions or minimize the 32 turbidity of discharge waters. While most selective withdrawal intakes structures are built during 33 initial reservoir construction, release structures can be successfully modified to incorporate 34 selective withdrawal as a retrofit, although this m ay be costly.

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Chapter 7. Hydromodification 27 2.2.4.5 Turbine Operation 1 Description 2 Turbine operations include implementation of change s in the turbine start-up procedures that can 3 enlarge the zone of withdrawal to include more of t he epilimnetic waters in the downstream 4 releases. 5 Application and Purpose 6 In an improvement effort that included changes in t urbine operation, the Tennessee valley 7 Authority (TVA) made operational changes and instal led additional equipment to ensure 8 minimum water flows through its dams. 9

Cost Data 10 Since the early 1990s, the TVA has spent about $60 million to address DO problems below 11 dams, including turbine operation. 12

Reference 13 Tennessee Valley Authority, No Date. Tailwater Impr ovements: Improving Water Quality Below 14 TVA Hydropower Dams. 15

2.2.4.6 Turbine Venting 16 Description 17 Turbine venting is the practice of injecting air in to water as it passes through a turbine. If vents 18 are provided inside the turbine chamber, the turbin e will aspirate air from the atmosphere and 19 mix it with water passing through the turbine as pa rt of its normal operation. Autoventing 20 turbines are constructed with hub baffles, or defle ctor plates placed on the turbine hub upstream 21 of the vent holes to enhance the low-pressure zone in the vicinity of the vent and thereby 22 increase the amount of air aspirated through the ve nting system. 23
Application and Purpose 24 Developments in turbine venting technology show pot ential for aspirating air with no resulting 25 decrease in turbine efficiency, however, the applic ation of turbine venting technologies is site26 specific and outcomes will vary considerably. 27 Efficiency Data 28 Turbine efficiency relates to the amount of energy output from a turbine per unit of water passing 29 through the turbine. Efficiency decreases as less p ower is produced for the same volume of 30 water. In systems where the water is aerated before passing through the turbine, part of the water 31 volume is displaced by the air, thus leading to dec reased efficiency. 323/15/20 2

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Chapter 7. Hydromodification 28 

### 2.2.5 Implementation Measure #5: Restore Stream and Shoreline Physical 1 

### Characteristics 2 Implementation Measure: The restoration of stream and shoreline physical ch aracteristics is important to restoring predevelopment hydrology and reducing loading from larger and scouring flows. Degraded streams can themselves become a sou rce of downstream pollution, such as when phosphorus-laden sediments are mobilized durin g high flow events. In such cases, stream restoration can be a useful strategy to improve dow nstream water quality. However, it is important to keep in mind that the elevated flows c ausing sediment mobilization must also be addressed (see the Urban chapter). Stream stabiliza tion requires restoration of the stream’s energy signature. The predevelopment hydrology of t he watershed must be restored to regain the predevelopment character of the stream; however, in existing urban areas, that might be a longerterm goal. The primary goal of this implementation measure is to 1. Restore stable relationship between watershed hy drology and stream and shoreline geometry. Where streambank or shoreline erosion is a nonpointsource pollution problem, streambanks and shorelines should be stabilized. Vegetative met hods are strongly preferred unless structural methods are more effective, considering the severity of stream flow discharge, wave and wind erosion, offshore bathymetry, and the pote ntial adverse effect on other streambanks, shorelines, and offshore areas.
Stream restoration can help to restore the natural ecosystem function of N removal that occurs in 3 streams. Studies that evaluate the N removal abilit y of restored streams are summarized in Table 4 7-2. 5
Table 7-2. Studies evaluating the N removal abilityof restored streams in the chesapeake bay 6 watershed 7 T he restoration of

stream and shoreline physical characteristics is important to restoring 8 predevelopmenthydrology and reducing loading from larger and sco uring flows. Degraded 9 streams can themselves become a source of downstrea m pollution, such as when phosphorus

10 laden sediments are mobilized during high flow even ts. In such cases, stream restoration can be a 11 useful strategy to improve downstream water quality . However, it is important to keep in mind 12 that the elevated flows causing sediment mobilizati on must also be addressed (see urban 13 chapter). Stream stabilization requires restoration of the stream’s ene rgy signature. The 14 predevelopment hydrology of the watershed must be r estored to regain the predevelopment 15 character of the stream ; however, in existing urban areas , t hat mightbe a longer term goal. The 16 primary goal of

this implementation measure is to 17
1. Restore stable relationship between watershed hydro logy and streamand shoreline geometry

. 18 Where streambank or shoreline erosion is a nonpointsource pollution problem, streambanks 19 and shorelines should be stabilized. Vegetative met hods are strongly prefe rred unless 20 structural methods are more effective, considering the severity of stream flow discharge, wave 21 and wind erosion, offshore bathymetry, and the pote ntial adverse effe ct on other streambanks, 22 shorelines, and offshore areas. 233/15/20 2

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Chapter 7. Hydromodification 29 Stream restoration can help to restore the natural ecosystem function of n itrogen removal that 1 occurs in streams. Studies that evaluate the nitrogen removal ability of restored streams are 2 summarized in Table 7

- 2

. 3

Table 7
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. Studies Evaluating the Nitrogen Removal Ability of Res tored Streams in the 4 Chesapeake Bay Watershed 5 Study Finding Kausal, Sujay S., et.al. Effects of Stream Restoration on Denitrification in an Urbanizing Watershed. Ecological Applications, 18(3), 2008, pp. 789-804. Streams with ecological functions intact remove N nitrogen at a much higher rate than degraded urban streams, and stream restoration practices can restore this N nitrogen removal function Klocker et al. Nitrogen uptake and denitrification in restored and unrestored streams in urban Maryland, USA . Aquatic Sciences, Accepted October 2009. Degraded urban streams, deeply eroded and disconnected

from their floodplain have substantially lower rates of N nitrogen removal that than streams hydraulically connected to their riparian banks via low slopes, and reconnecting the stream to the floodplain can increase
In addition to the water quality improvements that can be achieved through stream restoration, 6 the flood management community has become increasin gly aware of the benefits of restoration 7 in preventing flood damages. The Association of Sta te Floodplain Managers (ASFPM) has 8 prepared a white paper called Natural and Beneficial Floodplain Functions: Floodp lain 9 Management— More than Flood Loss Reduction ( http://www.floods.org ), which emphasizes the 10 multiple benefits of protecting and restoring strea ms and their associated floodplains. 11 Techniques for stream and floodplain restoration ar e also described in the Riparian Section of 12 this guidance document. Example references for stre am restoration, and for information on the 13 impacts of urban runoff to stream ecosystems, are p rovided in Table 7-3. 14

Table 7-3. References on urban stormwater effects o n streams with emphasis on restoration and 15 habitat 16 USDA Natural Resources Conservation Service, Part 654 Stream Restoration Design National Engineering Handbook, 210–VI–NEH, August 2007 Federal Interagency Stream Restoration Working Grou p (FISRWG) (1998 ). Stream Corridor Restoration: Principles, Processes, and Practices
, ISBN-0-934213-60-7, Distributed by the National Technical Information Service at 1-800-533-6847. Infiltration vs. Surface Water Discharge: Guidance for Stormwater Managers, Final Report . 03-SW-4, Water Environment Research Federation (WERF 2006) A ppendix B. Assessment of Existing Watershed Conditions: Effects on Habitat.

2.2.5.1 Existing practices 17 The National Management Measures to Control Nonpoint So urces Pollution from 18 Hydromodification document (USEPA published by EPA in 2007 ) provides information on using 19 the following practices to restore stream and shore line physical characteristics: 20

• Branch Packing 21

• Brush Layering 223/15/20 2

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Chapter 7. Hydromodification 30 • Dormant Post Plantings 1

• Root Wad Revetments 2

• Tree Revetments 3

2.2.5.2 Bank Shaping and Planting 4 Description 5 Bank shaping and planting involves regrading a stre ambank to establish a stable slope angle, 6 placing topsoil and other material needed for plantgrowth on the streambank, and selecting and 7 installing appropriate plant species on the streamb ank. 8
Application and Purpose 9 Bank shaping and planting is most successful on str eambanks where moderate erosion and 10 channel migration are anticipated. Reinforcement atthe toe of the bank is often required, 11 particularly where flow velocities exceed the toler ance range for plantings and where erosion 12 occurs below base flows. 13 Efficiency Data 14 Nearly 400 rock riprap grade-control structures ( hereafter GCS) were recently placed in streams 15 of western Iowa, to reduce streambank erosion and p rotect bridge infrastructure and farmland. In 16 that region, streams are characterized by channeliz ed reaches, highly incised banks, and silt and 17 sand substrates that normally support low macroinve rtebrate abundance and diversity. Therefore, 18 GCS composed of riprap provide the majority of coar se substrate habitat for benthic 19 macroinvertebrates in these streams. Litvan et al. (2008) sampled 20 sites on Walnut Creek, 20 Montgomery County, Iowa, to quantify macroinvertebr ate assemblage characteristics (1) on GCS 21 riprap, (2) at sites 5–50 m upstream of GCS, (3) at sites 5–50 m downstream of GCS and (4) at 22 sites at least 1 km from any GCS (five sites each). Macroinvertebrate biomass, numerical 23 densities and diversity were greatest at sites with coarse substrates, including GCS sites and one 24 natural riffle site and relatively low at remaining sites with soft substrates. Densities of 25 macroinvertebrates in the orders Ephemeroptera, Tri choptera, Diptera, Coleoptera and 26 Acariformes were abundant on GCS riprap. Increases in macroinvertebrate biomass, density , and 27 diversity at GCS might improve local efficiency of breakdown of organic matter and nutrient and 28 energy flow, and provide enhanced food resources fo r aquatic vertebrates. However, lack of 29 positive macroinvertebrate responses immediately up stream and downstream of GCS suggest 30 that positive effects might be restricted to the sm all areas of streambed covered by GCS. 31 Improved understanding of GCS effects at both local and ecosystem scales is essential for stream 32 management when these structures are present. 33

2.2.5.3 Brush Mattressing 34 Description 35 A brush mattress is a layer (mattress) of interlace d live branches placed on a bank face, often 36 with a live fascine and/or rock at the base. This m at is then secured to the bank by live and/or 37 dead stakes and partially covered with fill soil to initiate growth of the cuttings. 383/15/20 2

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Chapter 7. Hydromodification 31 Application and Purpose 1 Brush mattressing is commonly used in Europe for streambank protection. It involves digging a 2 slight depression on the bank and creating a mat ormattress from woven wire or single strands of 3 wire and live, freshly cut branches from sprouting trees or shrubs. Branches approximately one 4 inch in diameter are normally cut 6 to 9 feet long (the height of the bank to be covered) and laid 5 in criss-cross layers with the butts in alternating directions to create a uniform mattress with few 6 voids. The mattress is then covered with wire secur ed with wooden stakes 2.5 to 4 feet long. It is 7 then covered with soil and watered repeatedly to fi ll voids with soil and facilitate sprouting; 8 however, some branches should be left partially exp osed on the surface. The structure might 9 require protection from undercutting by placement o f stones or burial of the lower edge. Brush 10 mattresses are generally resistant to waves and cur rents and provide protection from the digging 11 out of plants by animals. Disadvantages include pos sible burial with sediment in some situations 12 and difficulty in making later plantings through th e mattress. 13 Brush mattresses can restore riparian vegetation an d habitat and enhance conditions for 14 colonization of native plants. They reduce soil ero sion and intercept sediment flowing down the 15 streambank. After vegetation reaches a height of a few feet, it can improve fish habitat by 16 shading the stream, lowering water temperatures andoffering protection from predators (Allen 17 and Fischenich 2000). Brush mattresses are also use ful on steep, fast-flowing streams. 18

Cost Data 19 Costs for brush mattresses range between $3 and $14 per square foot (Allen and Fischenich 20 2000). Costs can be reduced by using free material from donation sites and volunteer labor. 21 Costs related to project permitting or planning are not included in the estimate. 22 Design Guidance and additional info 23 Installation guidelines are available from the USDA -FS Soil Bioengineering Guide (USDA-FS 24 2002). Under the Ecosystem Management and Restorati on Research Program (EMRRP), the 25 USACE has presented research on brush mattresses in a technical note (Brush Mattresses for 26 Streambank Erosion Control). 27

2.2.5.4 Cross Vanes 28 Description 29 A rock cross vane is a stone structure consisting o f footer and vane rocks constructed in a way 30 that provides grade control and reduces bank erosio n. The vane is composed of a center section 31 perpendicular to the streambanks joined to two arms that extend into the streambank at the 32 channel flow height. The rock cross vane accumulate s sediment behind the vane arms, directs 33 flow over the cross vane, and creates a scour pool downstream of the structure. 34
Application and Purpose 35 Low profile in-stream structures, such as cross van es, are primarily used to create aquatic habitat 36 in the form of scour pools and for grade control on incising streams and rivers. Additionally, they 37 are well-suited for channeling flow away from unstable banks. Cross vanes are typically suited 38 for use in moderate to high gradient streams. When constructed and spaced properly, cross vanes 393/15/20 2

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Chapter 7. Hydromodification 32 can simulate the natural pattern of pools and riffl es occurring in undisturbed streams while 1 forming gravel deposits which fish use as spawning grounds. Cross vanes can also be used to 2 stabilize banks when designed properly. Cross vanes should be avoided in channels with bedrock 3 beds or unstable bed substrates, and streams with n aturally well developed pool-riffle sequences. 4 Cross Vanes are appropriate for the following: 5

• Stabilization of a vertically unstable stream bed r equires grade control 6

• To direct erosional forces away from the streambank s and to the center of the channel 7

• When fish habitat enhancement and grade control are both desired 8

• For bridge protection. Cross vanes provide grade co ntrols, prevent lateral migration of 9 channels, increase sediment transport capacity and competence, and reduce footer scour 10

• To enhance or create recreational paddling opportun ities 11

• Most suitable for rapid-dominated stream systems wi th gravel/cobble substrate 12

Cost Data 13 Construction costs for cross vanes are highly variable, depending on the design, size of the stone, 14 availability of materials, and site constraints. 15

2.2.5.5 Joint Planting 16 Description 17 Joint planting involves tamping live stakes of root able plant material or rooted cuttings into soil 18 in the interstices of porous revetments, riprap, or other retaining structures. 19 Joint planting is useful where rock riprap is requi red or already in place. It is successful 30 to 50 20 percent of the time, with first year irrigation imp roving survival rates. Live cuttings must have 21 side branches removed and bark intact. They should range from 0.5 to 1.5 inches in diameter and 22 be long enough to extend well into the soil, reachi ng into the dry season water level. 23
Application and Purpose 24 Joint planting can improve aquatic habitat by provi ding food and cover in the riparian zone and 25 over the water when they are used in close proximit y to the edge of the stream. Stone used at the 26 base of the joint planting produces substrates suit ed for an array of aquatic organisms. Some of 27 these organisms adapt to living on and within the r ocks and some attach to the leaves and stems. 28 The leaves and stems can also become food for shred ders. 29 Species for joint planting systems can be selected to provide color, texture, and other attributes 30 that add a pleasant, natural landscape appearance. Such plants for these systems include willow 31 (Salix spp.), which tends to be the best from an ad ventitious rooting perspective and is normally 32 an excellent choice. However other species such as poplar (Populus spp.), Viburnum spp., 33 Hibiscus spp., shrub dogwood (Cornus spp.) and butt onbush (Cephalanthus), also work well. 34 After establishment, joint planting system can redu ce non-point pollution by intercepting 35 sediment and attached pollutants that otherwise ent er the stream from overbank flow areas. 363/15/20 2

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Chapter 7. Hydromodification 33 Cost Data 1 Joint planting ranges in cost between $1 to $5 per square foot (Gray 1996). ( Gray and Sotir 2 1996 ). Costs do not include riprap and assumes a spacing of 4 cuttings per square yard. 3 Design Guidance and additional info 4 Installation guidelines are available from the USDA FS Soil Bioengineering Guide (USDA-FS 5 2002) and the USDA NRCS Engineering Field Handbook , Chapter 18 (USDA-NRCS 1992). 6

2.2.5.6 Legacy Effects of Dams and Dam Removal 7 Description 8 Dam removal is the process of dismantling and remov ing unsafe, unwanted or obsolete dams and 9 restoring the original stream gradient to the exten t possible. 10
Application and Purpose 11 Dams serve a variety of important social and enviro nmental purposes, including water supply, 12 flood control, power generation, wildlife habitat a nd recreation ( US EPA 2007). Dam removal is 13 undertaken either by owners of the dam or by public agencies and might become necessary for 14 various reasons. These include most notably the phy sical or structural deterioration of the dam 15 resulting in a public safety risk, sediment accumul ation in the impoundment/reservoir behind the 16 dam and corresponding deleterious effects on the qu ality and quantity of water supplies. There 17 are many things to consider when removing a dam, on e of which is the function(s) of the dam 18 and the status of that function (active vs. inactiv e). Sometimes the need for the dam is no longer 19 be as important as it once was, usually because of eco nomic considerations. Finally, ecological 20 concerns sometimes drive the need for dam removal. For example, migratory fish passage 21 throughout United States rivers and streams is obstructed by over 2 million dams and many other 22 barriers such as blocked, collapsed, and perched cu lverts (USEPA 2007). Because dams are 23 capital intensive, long-term ventures, the opportun ity for dam removal typically occurs 24 infrequently, often corresponding to their periodic licensing renewal. 25 Efficiency Data 26 Many rivers and streams of the Mid-Atlantic Region, United States have been altered by 27 postcolonial floodplain sedimentation (legacy sedim ent) associated with numerous milldams. 28 Little Conestoga Creek, Pennsylvania, a tributary t o the Susquehanna River and the Chesapeake 29 Bay, is one of these streams. Floodplain sedimentat ion rates, bank erosion rates, and channel 30 morphology were measured annually during 2004-2007 at five sites along a 28-km length of 31 Little Conestoga Creek with nine colonial era milld ams (one dam was still in place in 2007). A 32 study by Schenk and Hupp (2009) Schenk et al

. (2009) was part of a larger cooperative effort to 33 quantify floodplain sedimentation, bank erosion, an d channel morphology in a high sediment 34 yielding region of the Chesapeake Bay watershed. 35
Data from the five sites were used to estimate the annual volume and mass of sediment stored on 36 the floodplain and eroded from the banks for 14 seg ments along the 28-km length of creek. A 37 bank and floodplain reach based sediment budget (se diment budget) was constructed for the 28 38 km by summing the net volume of sediment deposited and eroded from each segment. Mean 393/15/20 2

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Chapter 7. Hydromodification 34 floodplain sedimentation rates for Little ConestogaCreek were variable, with erosion at one 1 upstream site (5 mm⁄ year) to deposition at the oth er four sites (the highest was 11 mm⁄ year) 2 despite over a meter of floodplain aggradation frompostcolonial sedimentation. Mean bank 3 erosion rates range between 29 and 163 mm⁄ year amo ng the five sites. Bank height increased 1 1 4 m for every 10.6 m of channel width, from upstream to downstream (R2 = 0.79, p < 0.0001) 5 resulting in progressively lowered hydraulic connec tivity between the channel and the 6 floodplain. 7 A knickpoint approximately 9 km upstream of the damhas produced a net erosional environment 8 in the upstream two river segments. The floodplain experienced short periods of inundation 9 nearly annually at the USGS streamgage, between the knickpoint and the dam, despite the 10 heightened banks from postcolonial sedimentation an d subsequent dam removals. Sediment 11 trapping was recorded at four of the five study sit es, indicating that the aggraded Little 12 Conestoga Creek floodplain still functions as a sed iment sink. 13 The study concluded that dam removals have many ben efits, but they come with the cost of 14 remobilizing large amounts of sediment. Managers an d policy makers in the Northeast and Mid15 Atlantic states will have the additional burden of managing the storage and transport of legacy 16 sediment. Dam removals in these regions can lead to large and sustained sediment pulses as 17 legacy sediment is remobilized and transported furt her downstream, where increased 18 sedimentation is a critical concern for imperiled e stuarine resources, in this case the Susquehanna 19 River and the Chesapeake Bay. 20 Gravel-bedded streams are thought to have a charact eristic meandering form bordered by a self 21 formed, fine-grained floodplain. This ideal guides a multibillion-dollar stream restoration 22 industry. Walter and Merritts (2008) Walter et al

. (2008) mapped and dated many of the deposits 23 along mid-Atlantic streams that formed the basis fo r this widely accepted model. These data, as 24 well as historical maps and records, show instead t hat before European settlement, the streams 25 were small anabranching channels within extensive v egetated wetlands that accumulated little 26 sediment but stored substantial organic carbon. Sub sequently, 1 to 5 meters of slackwater 27 sedimentation, behind tens of thousands of 17th- to 19th-century milldams, buried the 28 presettlement wetlands with fine sediment. These fi ndings show that most floodplains along mid29 Atlantic streams are actually fill terraces, and hi storically incised channels are not natural 30 archetypes for meandering streams. The study conclu des that fluvial aggradation and degradation 31 in the eastern United States were caused by human-i nduced base level changes from the 32 following processes: 33

• Widespread milldam construction that inundated pres ettlement valleys and converted 34 them into a series of linked slackwater ponds, coup led with deforestation and agricultural 35 practices that increased sediment supply 36

• Sedimentation in ubiquitous millponds that graduall y converted these ponds to sediment37 filled reservoirs 38

• Subsequent dam breaching that resulted in channel i ncision through postsettlement 39 alluvium and accelerated bank erosion by meandering streams 40

• The formation of an abandoned valleyflat terrace an d a lower inset floodplain, which 41 explains why so many eastern streams have bankfull (discharge) heights that are much 423/15/20 2

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Chapter 7. Hydromodification 35 lower than actual bank heights (note that assessmen ts of bankfull discharge are crucial to 1 estimates of flood potential and to design criteria for stream restoration). 2
Most research to date has considered western and ea stern streams in the United States to have 3 similar origins and forms, however, western streams are in a more tectonically active region, 4 generally have high stream gradients, and carry sub stantial bed-load fractions, whereas eastern 5 Piedmont streams are in a tectonically quiescent re gion, have low stream gradients, and largely 6 did not carry gravel (or even much fine sediment) d uring the Holocene before formation of 7 modern incised channels. Formation of gravel bars i n the wake of eroding, meandering channels, 8 followed by overbank deposition of fine sediment, w as not the natural process of floodplain 9 formation in the eastern United States before mill damming and subsequent channel incision 10 after dam breaching. Valley bottoms along eastern s treams were characterized by laterally 11 extensive, wetland-dominated systems of forested me adows with stable vegetated islands and 12 multiple small channels during recent geologic time (Holocene). These findings are consistent 13 with research on streams in the Pacific Northwest, which revealed that large, woody debris from 14 forested, riverine areas was critical to geomorphic processes and habitat before logging, channel 15 clearing, and ditching during the late 1800s to ear ly 1900s. In particular, logjams blocked 16 channels and led to the formation of side channels and floodplain sloughs, producing multiple 17 anabranching channels and riverine wetlands that ar e in stark contrast to the large, single 18 channels that exist in these streams today. 19 Results of this study explain the unusually thick d eposits of fine sediment in streambanks relative 20 to the limited amount of modern overbank deposition and the lack of levees on mid-Atlantic 21 streams. Also explained are the great contrast betw een fine stream-bank and coarse stream-bed 22 material; the observation that eastern (incised) streams, in comparison with western streams, 23 change little in width as discharge increases at a station and the anomalously high suspended 24 sediment and nutrient loads measured in Piedmont streams. Postsettlement milldam construction 25 and millpond sedimentation were rapid and pervasive . This process inundated, buried, and 26 sequestered presettlement wetlands and altered regi onal stream functions probably within two 27 generations of settlement. Our field and historical research shows that stream valleys were once 28 lined with millponds, which then silted in to form broad, flat bottom lands. Modern, incised, 29 meandering streams are an artifact of the rise and fall of Mid-Atlantic streams in response to 30 human manipulation of stream valleys for water powe r. Our results indicate that a substantial 31 portion of modern suspended sediment and nutrient l oads could be due to dam breaching and 32 erosion of reservoir sediment, which is consistent with studies of recent dam removals elsewhere 33 in the United States. These conclusions change the interpretation of hydraulic geometry in 34 eastern United States streams that is based on the archetype of an “ideal meandering river form” 35 and imply the need to reconsider current procedures for stream restoration that rely on reference 36 reach conditions and the assumption that eroding ch annel banks are natural and replenishable. 37 The current condition of single gravel-bedded chann els with high, fine-grained banks and 38 relatively dry valley-flat surfaces disconnected fr om groundwater is in stark contrast to the 39 presettlement condition of swampy meadows (shrub-sc rub) and shallow anabranching streams 40 described here might have been the result of mill d amming. 41 Stanley and Doyle (2002) St anley et al

. (2002) presented a geomorphic perspective on nutrient 42 retention following dam removal from streams and ri vers in Wisconsin reflecting the influence 43 of more than 100 years of human activity. In additi on to dam construction these systems have 443/15/20 2

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Chapter 7. Hydromodification 36 been subjected to upland and channel alterations th at include deforestation, wetland drainage, 1 soil inputs from poor farming practices, and nutrie nt enrichment from point and nonpoint 2 sources. There are approximately 3700 dams, or 1 da m every 14 kilometers of river in Wisconsin 3 Department of Natural Resources (WDNR ) ( 1995). Although there is a healthy representation o f 4 large dams (structures > 2 meters [m] that impound ≥ 62,000 m 3 , or structures > 7.6 m that 5 impound 18,500 m3; USACE 1998), state waterways are more commonly populated by high 6 densities of small, run-of-river structures, many o f which are well over 80 years old. (Run-of7 river structures are dams that create reservoirs wi th small storage capacity and do not alter the 8 river’s flow regime.) The abundance of dams can be traced back to the Milldam Act of 1840, 9 which encouraged using hydropower to fuel the state ’s burgeoning economy (Martini 1998). 10 Unfortunately, many of these structures are no long er economically viable, represent a safety 11 risk, and compromise the quality of the aquatic res ource (Born et al. 1998). Under these 12 circumstances, dam removal is a logical management option, and more than 50 dams have been 13 removed under the supervision of the WDNR over the past three decades. To date, and reflective 14 of the national trend (Doyle et al. 2005) (Doyle et al. 2000), most dams that have been removed 15 within the state were relatively small structures. 16 The growing interest and occurrence of dam removal underscores the inextricable link between 17 agriculture and river modification in the Midwest. Dams were often built for milling of 18 agricultural products, and the sediment-trapping ab ility of reservoirs means that topsoil and 19 nutrients lost from farm fields are now stored behi nd dams. Given the growing concerns about 20 nutrient enrichment and the potential for dam remov al to affect nutrient dynamics, understanding 21 the effects of dam removal on nutrient processes sh ould be a research and management priority. 22 The study draws from the context of agriculturally dominated watersheds in Wisconsin to 23 explore how dam removal could influence the movemen t of N and P in rivers, considering 24 nutrient transport in rivers and how reservoirs can affect nutrient processes. Changes in nutrient 25 dynamics following dam removal are considered with respect to geomorphic adjustments and 26 ecosystem responses caused by the removal. 27 The major theme emphasized in the study is that cha nges in nutrient retention caused by dam 28 removal are expected to be shaped by geomorphic cha nnel adjustments. Although the specific 29 way in which channels adjust to dam removal will vary from region to region, the change in the 30 physical template will strongly influence the ecolo gical responses to dam removal. Changes in 31 nutrient retention following dam removal should be complex, reflecting a balance between the 32 dynamics of channel adjustment and the relative inf luence of different channel stages on N and P 33 processing. Following dam removal, affected section s of a river can consist of a series of reaches 34 that have distinct and potentially contrasting infl uences on the form and amount of nutrients 35 being transported downstream. 36 Dam removal represents an extreme example of the in fluence of channel morphology on nutrient 37 dynamics in streams and rivers. While it is impossi ble to ignore the dramatic and relatively rapid 38 geomorphic changes when studying dam removal, strea ms and rivers are dynamic physical 39 systems subject to short- and long-term changes in channel form. Yet channel geomorphology is 40 usually treated as a fixed or constant attribute in ecological studies. As channels change over 41 time or from site to site in a stream, the extent o f sediment– water contact or the rate of sediment 42 transport will also vary. For example, the transiti on from a narrow and deep incised channel to a 43 broader, shallow channel under conditions of consta nt discharge will be accompanied by a 443/15/20 2

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Chapter 7. Hydromodification 37 decline in water velocity, an increase in wetted pe rimeter, and probably an increase in the 1 amount of interstitial flow. Because geomorphic adj ustments can alter sediment transport and the 2 extent of sediment–water contact, changing channel form alone has the potential to affect uptake 3 lengths and rates of biologically important element s such as N and P. Although the general 4 importance of channel form on a range of ecosystem processes, including nutrient cycling, is 5 well established (Brussock et al. 1985, Frissell etal. 1986, D’Angelo et al. 1997), specific 6 geomorphic attributes constrain nutrient dynamics i n lotic systems are just beginning to be 7 understood. Dam removal can be used as an experimen t for testing predictions or quantifying 8 relationships between the dynamics of channel form and nutrient retention and thus represents a 9 rare opportunity to gain valuable insights into the transport and transformation of nutrients as 10 they move through watersheds. 11 A study by Skalak et al. (2009) Skalak et al

. (2009) demonstrated that the effects of dams on 12 downstream channel morphology are minor. No signifi cant differences in the water surface slope 13 upstream and downstream of dams were observed. The study found that although monitoring 14 studies of dam removals are becoming more common ( Wildman and MacBroom; Bushaw15 Newton et al. 2002; Doyle et al. 2003; Chang 2008) Bushaw

- Newton et al. 2002; Doyle et al. 16 2003; Wildman and McBroom 2005; Cheng and Granata 2 007), empirical knowledge of the 17 effects of dam removal is still limited and most ob servations and conceptual models tend to 18 focus on the transient effects of dam removal, the shorter-term patterns of upstream sediment 19 mobilization and downstream sediment storage. 20 Very little research has been conducted on the long -term effects of dam removal, although Graf 21 ( 2006 2005 ) suggests that one of the most important unanswere d questions involves the likely 22 course of channel change following dam removal. The Skalak suggests that the results of their 23 study can provide some useful estimates of the long -term effects of dam removal on downstream 24 channels because the reaches upstream of existing d ams provide a useful surrogate for the 25 channel downstream before dam construction. If the dam is removed, the following scenario is 26 likely to occur. For an initial period of adjustmen t, sediment will be eroded from reservoir 27 deposits upstream, and a transient sediment pulse w ill likely pass into and through the reach 28 below the dam (Pizzuto 2002). During this period, c hanges in channel morphology and bed 29 composition might be expected. However, after the n ew channel within the reservoir reach has 30 stabilized, the supply of sediment and distribution of discharges should approach predam levels, 31 and the channel will slowly stabilize. We argue tha t the reach upstream of the dam has already 32 adjusted to these conditions, and therefore we use the characteristics of the upstream channels to 33 represent the equilibrium channel that will develop downstream of the dams long after dam 34 removal. 35 Following this approach, the results can be directl y applied as predictions of downstream channel 36 characteristics long after dam removal and the stud y proposes that long after dam removal, the 37 water surface width, slope, percent exposed bedrock , and percent boulders will be unchanged. 38 The median grain diameter will decrease slightly, b ut it will remain in the pebble size fraction. 39 The results of the study also have important implic ations for channel changes that could persist 40 long after the removal of the dams within the Chesapeake Bay watershed because the authors 41 argue that after an initial period of transient adj ustment as sediment eroded from upstream 42 reservoirs passes through downstream channels, chan ges in channel geomorphic characteristics 43 will be limited to increases in the percentages of silt and clay, sand, and granules, and that 443/15/20 2

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Chapter 7. Hydromodification 38 changes in the other geomorphic characteristics mea sured during this study will not be 1 detectable. Thus, dam removal projects in streams s imilar to those of our study area should not 2 cause significant long-term geomorphic changes to s tream channels downstream. 3

Cost Data 4 Costs of dam removal is site-specific and can vary from tens of thousands of dollars to hundreds 5 of millions of dollars, depending on the size and l ocation of the dam (USEPA 2007). 6

2.2.5.7 Live Crib Walls 7 Description 8 Live crib walls are hollow, box-like frameworks of untreated logs or timbers filled with riprap 9 and alternating layers of suitable backfill and liv e branch layers and are used for slope, 10 streambank, and shoreline protection. 11
Application and Purpose 12 Live crib walls are constructed to protect the toes and banks of eroding stream reaches against 13 scour and 14 undermining, particularly at the outsides of meande r bends where strong river currents are 15 present. The log frameworks provide immediate prote ction from erosion while the live branch 16 cuttings contribute long-term durability and ultima tely replace the decaying logs. Additionally, 17 live crib walls are effective in areas where encroa chment into the stream channel should be 18 avoided. When considering these structures as a str eam restoration technique, the following 19 limitations should be considered: 20

• Live crib walls should not be used where the channe l bed is severely eroded or where 21 undercutting is likely to occur (e.g., where the te rrain is rocky or where narrow channels 22 are bounded by high banks). 23

• Live crib walls are not intended to resist large la teral earth stresses, therefore their heights 24 should be limited accordingly (as noted in the inst allation specifications). 25

• Live crib walls promote siltation and retain large amounts of bed material; therefore they 26 require continual monitoring for adverse streamflow patterns. 27 When choosing and preparing logs and woody cuttings for live crib walls, the following 28 guidelines should be followed: 29

• Crib frameworks should be constructed from strippedlogs or untreated lumber 4 to 6 30 inches (10 to 15 centimeters) in diameter. 31

• Live branches should be cut from fresh, green, heal thy parent plants which are adapted to 32 the site conditions whenever possible. 33 1. Live branches should be 0.5 to 2.5 inches (1.3 t o 6 centimeters) in diameter and 34 should be long enough to reach the soil at the backof the wooden crib structure while 35 projecting slightly from the crib face. 363/15/20 2

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Chapter 7. Hydromodification 39

2. Commonly used woody plants for this measure incl ude willow, poplar, and alder 1 since they are versatile and have high growth rates with shrubby habits, fibrous root 2 systems, and high transpiration rates especially wh en in leaf. 3 3. Live branch cuttings should be kept covered and moist at all times and should be 4 placed in cold storage if more than a few hours elapse before installation. 5

• Fill soil should be native to the site, when possib le, and should contain enough fine 6 material to allow for the live branches to root andgrow readily. 7

Cost Data 8 Live crib walls range in cost between $13 to $33 pe r square foot (Gray 1996) ( Gray and Sotir 9 1996 ). 10 Design Guidance and additional info 11 Installation guidelines are available from the USDA -FS Soil Bioengineering Guide (USDA-FS 12 2002) and the USDA NRCS Engineering Field Handbook , Chapter 18 (USDA-NRCS 1992). 13

Additional Resources 14 FISRWG (Federal Interagency Stream Restoration Working Gr oup) . 1998. Stream Corridor 15 Restoration: Principles, Processes, and Practices. Federal Interagency Stream Restoration 16 Working Group. 17 http://www.nrcs.usda.gov/technical/stream_restorati on/PDFFILES/APPENDIX.pdf. 18 ISU (Iowa State University). 2006. How to Control Streambank Erosion: Live Cribwall . Iowa 19 State University. http://www.ctre.iastate.edu/erosion/manuals/streamb ank/live_cribwall.pdf. 20 Mississippi State University, Center for Sustainabl e Design. 1999. Water Related Best 21 Management Practices in the Landscape: Live Cribwal l . Prepared for the U.S. Department 22 of Agriculture, Natural Resource Conservation Servi ce, Watershed Science Institute. 23 http://www.abe.msstate.edu/csd/NRCS-BMPs/pdf/stream s/bank/livecribwall.pdf. 24
Ohio DNR (Department of Natural Resources) . No date. Ohio Stream Management Guide: Live 25 Cribwalls . Ohio Department of Natural Resources. 26 http://www.ohiodnr.com/water/pubs/fs_st/stfs17.htm. 27

2.2.5.8 Live Fascines 28 Description 29 A form of soil bioengineering which uses long bundl es of live branch cuttings bound together in 30 long rows and placed in shallow trenches following the contour on dry slopes, and at an angle on 31 wet slopes. 32
Application and Purpose 33 Live fascines are suited to steep, rocky slopes, wh ere digging is difficult (USDA-NRCS 1992). 34 When cut from appropriate species (e.g., young will ows or shrub dogwoods) that root easily and 35 have long straight branches, and when properly inst alled, they immediately begin to stabilize 363/15/20 2

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Chapter 7. Hydromodification 40 slopes. Willow, alder, and dogwood cuttings are wel l suited for use in live fascines. Fascine 1 bundles can range from 5 to 30 feet (1.5 to 9 meter s) in length, depending upon handling and 2 transportation limitations, with diameters ranging from 4 to 10 inches (10 to 25 cm). Untreated 3 twine or wire used to tie the bundles should be at least 2 millimeters thick. If inert (dead) stakes 4 are employed to secure the bundles, they should be made from 2 by 4 inch (5 by 10 cm) lumber 5 cut on the diagonal with lengths of 2.5 feet (0.8 m eters) for cut slopes and 3 feet (0.9 meters) for 6 fill slopes.The goal is for natural recruitment to follow once slopes are secured. Live fascines 7 should be placed in shallow contour trenches on dryslopes and at an angle on wet slopes to 8 reduce erosion and shallow face sliding. Live fasci nes should be applied above ordinary high9 water mark or bankfull level except on very small d rainage area sites. In arid climates, they 10 should be used between the high and low water marks on the bank. This system, installed by a 11 trained crew, does not cause much site disturbance. 12 Establishing Establishment of live fascines, also known as wattles, consists of t he following: 13

• Preparing sausage-shaped bundles of live, woody pla nt cuttings 14

• Anchoring the bundles in shallow ditches in a slope or streambank with live and/or inert 15 stout stakes 16

• Partially burying the fascines to promote growth 17 As with other bioengineering measures, live fascine s are an economical method when materials 18 are locally available. Additionally, live fascines are often an effective measure when employed 19 to 20

• Reduce runoff energy, and hence surface erosion, bybraking a slope into a series of 21 shorter slopes 22

• Protect other bioengineering measures from washout and undercutting 23

• Replace brush layers on suitable cut slopes (since they are easier to install) 24

• Protect streambanks from washout and seepage, parti cularly at toes where water levels 25 fluctuate only moderately 26

• Stabilize or protect streambanks 27

• Provide habitat 28

• Reduce overland sediment loading 29

Cost Data 30 Live fascine costs range from $10 to $30 per foot f or 6- to 8-in.bundles. Prices include securing 31 devices for installation, twine (for fabrication), harvesting, transportation, handling, fabrication, 32 and storage of the live-cut branch materials, excav ation, backfill, and compaction. Costs vary 33 with design, access, time of year, and labor rates. 34 Design Guidance and additional info 35 Installation guidelines are available from the USDA -FS Soil Bioengineering Guide (USDA-FS 36 2002) and the USDA NRCS Engineering Field Handbook , Chapter 18 (USDA-NRCS 1992). 37 Under their Ecosystem Management and Restoration Re search Program (EMRRP), the U.S. 383/15/20 2

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Chapter 7. Hydromodification 41 Army Corps of Engineers presents research on live f ascines in a technical note (Live and Inert 1 Fascine Streambank Erosion Control). 2

Additional Resources 3 Massachusetts DEP. 2006. Massachusetts Nonpoint Source Pollution Management Manual: Live 4 Fascines . Massachusetts Department of Environmental Protect ion, Boston, MA. 5 http://projects.geosyntec.com/NPSManual/Fact%20Shee ts/Live%20Fascines.pdf. 6 Greene County Soil & Water Conservation District. N o date. Construction Specification VS-01: 7 Live Fascines. http://www.gcswcd.com/stream/library/pdfdocs/vs-01. pdf. 8
ISU (Iowa State University) . 2006. How to Control Streambank Erosion: Live Fascine . Iowa 9 State University. http://www.ctre.iastate.edu/erosion/manuals/streamb ank/live_fascine.pdf. 10 Mississippi State University, Center for Sustainabl e Design. 1999. Water Related Best 11 Management Practices in the Landscape: Live Fascine . Prepared for the U.S. Department 12 of Agriculture, Natural Resource Conservation Servi ce, Watershed Science Institute. 13 http://abe.msstate.edu/csd/NRCS-BMPs/pdf/streams/ba nk/livefacine.pdf. 14 Ohio DNR. No date. Ohio Stream Management Guide: Li ve Fascines. Ohio Department of 15 Natural Resources. http://www.ohiodnr.com/water/pubs/fs_st/stfs14.pdf. 16
2.2.5.9 Live Staking 17 Description 18 Live staking is used to reestablish streambank vege tation and help stabilize selected slope areas. 19 This form of soil bioengineering involves the plant ing of live cuttings from shrubs or trees along 20 the streambank and is also known as woody cuttings, posts, poles or stubs. Stakings provide 21 long-term streambank stabilization with delayed ini tial onset and are best used as part of a 22 system which includes immediate means of buffering banks from erosive flows (e.g., tree 23 revetments, which can actually accrue sediments), a component to deter undercutting at the 24 bed/bank interface (e.g., riprap or gabions) and a means of reducing the energy of incoming 25 flows at their source. 26
Application and Purpose 27 Live staking is an economical method when local sup plies of woody cuttings are readily 28 available since the implementation of this measure requires minimal labor. When used 29 effectively, live stakes can do the following: 30

• Act to trap soil particles in sediment laden water resulting from the erosion of adjacent 31 land 32

• Slow water velocities, trap sediment, and control e rosion when organized in clustered 33 arrays along the sides of gullies 34

• Repair small earth slips and slumps which are frequ ently wet 35

• Help control shallow mass movement when placed in r ows across slopes 36

• Promote bank stabilization 373/15/20 2

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Chapter 7. Hydromodification 42 Live staking is a preventative measure and should b e employed before severe erosion problems 1 occur. Additionally, to be effective, live stakes s hould be 2

• Planted only on streams with low to moderate flow f luctuations 3

• Established in the original bank soil on moderate s lopes of 4:1(h:v) or less 4

• Planted where appropriate lighting exists 5

• Used jointly with other restoration techniques espe cially on slopes with high erosion rates 6 and incidents of mass wasting 7 When choosing and preparing woody material for live stakes, managers should follow these 8 guidelines: 9

• Live stakes should be cut from fresh, green, health y, dormant parent plants which are 10 adapted to the site conditions whenever possible. C ommonly used woody plants for this 11 measure include willow, poplar, and alder since the y are versatile and have high growth 12 rates with shrubby habits, fibrous root systems, an d high transpiration rates, especially 13 when in leaf. 14

• Live stakes should have a diameter between 0.75 and1.5 inches (2 to 4 cm) and should 15 be long enough to reach below the groundwater table so that a strong root system can 16 quickly develop. At least 1 foot (0.3 m) should be exposed to sunlight. Live woody posts 17 with diameters up to 10 inches (0.25 m) and lengths ranging from 4 to 6 feet (1.2 to 1. 8 8 18 m) can also be used at the discretion of the projec t manager. 19

• Live stakes should be kept covered and moist at all times and should be placed in cold 20 storage if more than a few hours elapse between the cutting and replanting times. 21

• Vegetation selected should be able to withstand the degree of anticipated inundation, 22 provide year round protection, have the capacity to become well established under 23 sometimes adverse soil conditions, and have root, s tem, and branch systems capable of 24 resisting erosive flows. 25

• Specific site requirements and available cutting so urce will determine size. 26

Cost Data 27 The installed cost of Live Stakes typically ranges from $1 to $2 per stake, depending on local 28 labor rates, proximity of harvesting area to site, and other site variables. 29 Design Guidance and additional info 30 Installation guidelines are available from the USDA -FS Soil Bioengineering Guide (USDA-FS 31 2002) and the USDA NRCS Engineering Field Handbook , Chapter 18 (USDA-NRCS 1992). 32

Additional Resources 33 ISU (Iowa State University) . 2006. How to Control Streambank Erosion: Live Stakes . Iowa State 34 University. http://www.ctre.iastate.edu/erosion/manuals/streamb ank/live_stakes.pdf

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Chapter 7. Hydromodification 43 Myers, R.D. 1993. Slope Stabilization and Erosion Control Using Vegetation: A Manual of 1 Practice for Coastal Property Owners. Live Staking

. Publication 93-30. Washington 2 Department of Ecology, Shorelands and Coastal Zone Management Program, Washington 3 Department of Ecology. Olympia , WA . Publication 93

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. 4 http://www.ecy.wa.gov/programs/sea/pubs/93-30/lives taking.html

. 5 Walter, J., D. Hughes, and N.J. Moore. 2005. Streambank Revegetation and Protection: A Guide 6 for Alaska. Revegetation Techniques: Live Staking . Revised Edition. Alaska Department of 7 Fish and Game, Division of Sport Fish. 8 http://www.sf.adfg.state.ak.us/SARR/restoration/tec hniques/livestake.cfm

. 9
2.2.5.10 Log & Rock Check Dams 10 Description 11 Check dams are low structures built across a streamperpendicular to the flow. The most 12 common use for check dams is to decrease the slope and velocity of a stream to control erosion. 13
Application and Purpose 14 The plunge pool below a check dam provides excellen t fish habitat, and the downstream gravel 15 bar often associated with the dam makes an excellen t spawning bed. When used to enhance fish 16 habitat, check dams should be placed far enough apart to insure that the pool below a dam is 17 above the backwater of the next dam downstream. Tha t will reduce the possibility that the habitat 18 pool of the upper dam can fill with deposits. 19 When constructed and spaced properly, check dams ca n simulate the natural pattern of pools and 20 riffles occurring in undisturbed streams while form ing gravel deposits that fish use as spawning 21 grounds. 22 Check dams have also been used to prevent the movem ent of fine sediments into the mainstream 23 channel, to aerate water, and to raise water levels past culvert invert elevations, thereby allowing 24 fish passage. 25 Check dams should be avoided in the following areas : 26

• Channels with bedrock beds or unstable bed substrat es 27

• Channels without well developed, stable banks 28

• Streams with high bedload transport 29

• Streams with naturally well developed pools-riffle sequences 30

• Reaches where the water temperature regime is negat ively impacted when the current is 31 slowed 32

Cost Data 33 Check dams vary widely in cost depending on the des ign, availability and selection of materials, 34 and site conditions. 353/15/20 2

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Chapter 7. Hydromodification 44 Design Guidance and additional info 1 The following document provide design information a nd guidance for check dams. 2 Maryland Department of the Environment Water Manage ment Administration. 2000. Maryland’s 3 Waterway Construction Guidelines. 4 http://www.mde.state.md.us/assets/document/wetlands waterways/mgwc.pdf. 5

2.2.5.11 Marsh Creation and Restoration 6 Description 7 Marsh creation and restoration is a useful vegetati ve technique that can address problems with 8 erosion of shorelines. For shoreline sites that are highly sheltered from the effects of wind, 9 waves, or boat wakes, the fill material is usually stabilized with small structures, similar to 10 groins, which extend out into the water from the la nd. For shorelines with higher levels of wave 11 energy, the newly planted marsh can be protected wi th an offshore installation of stone that is 12 built either in a continuous configuration or in a series of breakwaters. 13
Application and Purpose 14 The exposed stems of marsh plants form a flexible m ass that dissipates wave energy. As wave 15 energy is diminished, the offshore transport and lo ngshore transport of sediment are reduced. 16 Ideally, dense stands of marsh vegetation can creat e a depositional environment, causing 17 accretion of sediments along the intertidal zone ra ther than continued shore erosion. Marsh plants 18 also form a dense mat of roots, which can add stabi lity to the shoreline sediments. The basic 19 approach for marsh creation is to plant a shoreline area in the vicinity of the tide line with 20 appropriate marsh grass species. 21 Efficiency Data 22 Despite rapid growth in river restoration, few proj ects receive the necessary evaluation and 23 reporting to determine their success or failure andto learn from experience. As part of the 24 National River Restoration Science Synthesis, Alexander and Allan (2006) Alexand er and Allan 25 (2007) interviewed 39 project contacts from a database of 1,345 restoration projects in Michigan, 26 Wisconsin, and Ohio to (1) verify project informati on; (2) gather data on project design, 27 implementation, and coordination; (3) assess the ex tent of monitoring; and (4) evaluate success 28 and the factors that can influence it. Projects wer e selected randomly within the four most 29 common project goals from a national database: in-s tream habitat improvement, channel 30 reconfiguration, riparian management, and water-qua lity improvement. About half of the 31 projects were implemented as part of a watershed ma nagement plan and had some advisory 32 group. Monitoring occurred in 79 79 percent of projects but often was minimal and seldo m 33 documented biological improvements. Baseline data f or evaluation often relied on previous data 34 obtained under regional monitoring programs using s tate protocols. Although 89 percent of 35 project contacts reported success, only 11 11 percent of the projects were considered successful 36 because of the response of a specific ecological in dicator, and monitoring data were underused in 37 project assessment. Estimates of ecological success , using three criteria from Palmer and others 38 (2005), indicated that half or fewer of the project s were ecologically successful, markedly below 39 the success level that project contacts self-report ed, and sent a strong signal of the need for well40 designed evaluation programs that can document ecol ogical enhancements. 413/15/20 2

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Chapter 7. Hydromodification 45 2.2.5.12 Revetments 1 Description 2 Revetments are the stabilization of eroding streamb anks and for shoreline protection by using 3 designed structural measures, such as rock riprap, gabions, pre-cast concrete wall units and grid 4 pavers. 5 Application and Purpose 6 The purpose of revetments is to protect exposed or eroded streambanks from the erosive forces 7 of flowing water. They are generally applicable whe re flow velocities exceed 6 feet per second 8 or where vegetative streambank protection is inappr opriate and necessary where excessive flows 9 have created an erosive condition on a streambank. 10 Because each channel is unique, measures for struct ural streambank should be installed 11 according to a design according to specific site co nditions. Develop designs according to the 12 following principles: 13

• Make protective measures compatible with other chan nel modifications planned or being 14 carried out in the channel reaches. 15

• Use the design velocity of the peak discharge of th e 10-year storm or bankfull discharge, 16 whichever is less. Structural measures should be capable of withstanding greater flows 17 without serious damage. 18

• Ensure that the channel bottom is stable or stabili zed by structural means before installing 19 any permanent bank protection. 20

• Streambank protection should begin at a stable loca tion and end at a stable point along 21 the bank. 22

• Changes in alignment should not be done without a c omplete analysis of effects on the 23 rest of the stream system for both environmental an d stability effects. 24

• Provisions should be made to maintain and improve f ish and wildlife habitat. For 25 example, restoring lost vegetation will provide val uable shade, food, and/or cover. 26

• Ensure that all requirements of state law and all p ermit requirements of local, state, and 27 federal agencies are met. 28 Typical materials used for revetments are as follow s: 29 Riprap. Riprap is the most commonly used material to struc turally stabilize a streambank. While 30 riprap will provide the structural stabilization ne cessary, the bank can be enhanced with 31 vegetative material to slow the velocity of water, filter debris, and enhance habitat. 32
Gabions. Gabions are rectangular, stone-filled wire baskets . They are somewhat flexible in 33 armoring channel bottoms and banks. They can withst and significantly higher velocities for the 34 size stone they contain because of the basket struc ture. They also stack vertically to act as a 35 retaining wall for constrained areas. 363/15/20 2

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Chapter 7. Hydromodification 46 Reinforced Concrete. Reinforced concrete can be used to armor eroding s ections of streambank 1 by constructing walls, bulk heads, or bank linings. Provide positive drainage behind these 2 structures to relieve uplift pressures. 3
Grid Pavers. Grid pavers are modular concrete units with or with out void areas can be used to 4 stabilize streambanks. Units with void areas can al low the establishment of vegetation. Such 5 structures can be obtained in a variety of shapes o r they can be formed and poured in place. 6 Maintain design and installation in accordance with manufacturer’s instructions. 7
Modular Pre-Cast Units. Interlocking modular precast units of different siz es, shapes, heights, 8 and depths, have been developed for a wide variety of applications. These units serve in the same 9 manner as gabions. They provide vertical support in tight areas as well as durability. Many types 10 are available with textured surfaces. They also actas gravity retaining walls. They should be 11 designed and installed in accordance with the manuf acturers recommendations. Openings within 12 the units provide drainage and allow vegetation to grow through the blocks. Vegetation roots add 13 additional strength to the bank. 14
The National Management Measures to Control Nonpoint So urces Pollution from 15 Hydromodification document (USEPA published by EPA in 2007 ) provides various examples of 16 types of revetments. 17 Design Guidance and additional info 18 Ohio DNR. No date. Ohio Stream Management Guide: Riprap Revetments . Ohio Department of 19 Natural Resources. http://www.ohiodnr.com/water/pubs/fs_st/stfs16.pdf. 20

2.2.5.13 Rock and Log Vanes 21 Description 22 Rock and log vanes are single-arm structures which are partially embedded in the streambed 23 such that they are submerged even during low flows. 24
Application and Purpose 25 Rock and log vanes induce secondary circulation of the flow thereby promoting the development 26 of scour pools. Vanes can also be paired and positi oned in a channel reach to initiate meander 27 development or migration. They essentially mimic th e effect of a tree partially falling into the 28 stream. They are usually placed along the streamban k where erosion is occurring along the toe of 29 the slope. The purpose of vanes is to reduce erosio n along the streambank by redirecting the 30 stream flow toward the center of the stream. In add ition, they tend to create scour pools on the 31 downstream side. 32 Vanes can be made of rock or log. They grade down f rom the bankfull elevation at the 33 streambank to the channel invert at their terminus in the stream. Vanes generally extend out from 34 the streambank one-third of the bankfull width and are angled upstream from the bank at a 20 to 35 30 degree angle. They should be carefully located a nd installed so as not to produce additional 36 erosion on the upstream side where they meet the ba nk (eddy scour) or allow flows to outflank 37 them, exacerbating existing bank erosion problems. The only difference between the log vane 38 and the rock vane is the material used. The J-hook vane is basically the same as a rock vane with 393/15/20 2

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Chapter 7. Hydromodification 47 the exception that it curls around at the end in th e shape of a “J.” The curved end portion serves 1 to enhance downstream scour pool formation. 2 The following limitations apply to vanes: 3

• Vanes should not be used in unstable streams unless measures have been taken to 4 promote stream stability so that it can retain a co nstant planform and dimension without 5 signs of migration or incision. 6

• Vanes are ineffective in bedrock channels since min imal bed scouring occurs. 7 Conversely, streams with fine sand, silt, or otherw ise unstable substrate should be 8 avoided since significant undercutting can destroy these measures. 9

• Vanes should not be used in stream reaches that exc eed a 3 percent gradient. 10

• Vanes should not be used in streams with large sedi ment or debris loads. 11

• Banks opposite the these structures should be monitored for excessive erosi on. 12

Cost Data 13 Rock and log vanes vary greatly in cost depending o n the design, availability and selection of 14 materials, and site conditions. 15 Design Guidance and additional info 16 The following documents provide design information and guidance for vanes. 17 Stream Restoration: A Natural Channel Design Handbo ok, prepared by the North Carolina 18 Stream Restoration Institute and North Carolina Sea Grant. 19 http://www.bae.ncsu.edu/programs/extension/wqg/srp/ sr_guidebook.pdf 20 The Virginia Stream Restoration & Stabilization Bes t Management Practices Guide, Department 21 of Conservation and Recreation, Division of Soil an d Water Conservation. 2004. 22 http://www.dcr.virginia.gov/soil_and_water/document s/streamguide.pdf 23
2.2.5.14 Rosgen’s Stream Classification Method 24 Description 25 Rosgen’s stream channel stability method provides a sequence of steps for the field practitioner 26 to use in reaching final conclusions and making rec ommendations for management, stream 27 design, or restoration. 28
Application and Purpose 29 Field practitioners use field-measured variables to assess the following: 30

• Stream state or channel condition variables 31

• Vertical stability (degradation/aggradation) 32

• Lateral stability 33

• Channel patterns 343/15/20 2

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Chapter 7. Hydromodification 48 • Stream profile and bed features 1

• Channel dimension factor 2

• Channel scour/deposition (with competence calculati ons of field verified critical 3 dimensionless shear stress and change in bed and bar material size distribution) 4

• Stability ratings adjusted by stream type 5

• Dimensionless ratio sediment rating curves by strea m type and stability ratings 6

• Selection of position in stream type evolutionary s cenario as quantified by morphological 7 variables by stream type to determine state and pot ential of stream reach. 8 Stability assessments are conducted on a reference reach and a departure analysis is performed 9 when compared to an unstable reach of the same stre am type. Changes in the variables 10 controlling river channel form, primarily streamflo w, sediment regime, riparian vegetation, and 11 direct physical modifications can cause stream chan nel instability. Separating the differences 12 between anthropogenic versus geologic processes in channel adjustment is a key to prevention, 13 mitigation, and restoration of disturbed systems. 14 Efficiency Data 15 Restoration activities intended to improve the cond ition of streams and rivers are widespread 16 throughout the country but little information exist s regarding types of activities and their 17 effectiveness. Alexander and Allan (2006) Alexander and Allan (2006) developed a database of 18 1,345 stream restoration projects implemented from the years 1970 to 2004 for the states of 19 Michigan, Ohio, and Wisconsin to analyze regional trends in goals, presence of monitoring, 20 spatial distribution, size, and cost of river resto ration projects. They found that data on individual 21 projects were fragmented across multiple federal, s tate, and county agencies, as well as nonprofit 22 groups and consulting firms. The most common restor ation goals reported for this region were 23 in-stream habitat improvement, bank stabilization, water-quality management, and dam removal. 24 In a subsequent study, the National River Restorati on Science Synthesis (Alexander and Allan 25 2007) ( Alexander and Allan 2007) theyfound that despite rapid growth in river restorati on, few 26 projects receive the necessary evaluation and reporting to determine their success or failure and 27 to learn from experience. In this study, 39 projectcontacts from a database of 1,345 restoration 28 projects were interviewed to (1) verify project inf ormation; (2) gather data on project design, 29 implementation, and coordination; (3) assess the ex tent of monitoring; and (4) evaluate success 30 and the factors that can influence it. Projects wer e selected randomly within the four most 31 common project goals from the national database: in -stream habitat improvement, channel 32 reconfiguration, riparian management, and water-qua lity improvement. 33 About half of the projects were implemented as partof a watershed management plan and had 34 some advisory group. Monitoring occurred in 79 perc ent of projects but often was minimal and 35 seldom documented biological improvements. Baseline data for evaluation often relied on 36 previous data obtained under regional monitoring pr ograms using state protocols. Although 89 37 percent of project contacts reported success, only 11 percent of the projects were considered 38 successful because of the response of a specific ec ological indicator, and monitoring data were 39 underused in project assessment. Estimates of ecolo gical success, using three criteria from 40 Palmer and others (2005), indicated that half or fe wer of the projects were ecologically 413/15/20 2

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Chapter 7. Hydromodification 49 successful, markedly below the success level that p roject contacts self-reported, and sent a strong 1 signal of the need for well-designed evaluation pro grams that can document ecological success. 2 The importance of stream restoration to address the degradation of aquatic ecosystems is not in 3 doubt. However, based on this assessment of stream restoration practices in the upper midwest, 4 many aspects of stream restoration could be improve d. Project planning and implementation 5 should be cognizant of restoration needs and activi ties throughout the watershed to further their 6 understanding of the cumulative and interactive eff ects of dispersed restoration projects. In 7 addition, projects should be implemented with a for mal understanding of the larger landscape8 scale processes influencing the stream ecosystem. 9 Monitoring protocols for similar types of projects and reporting results should be standardized 10 regionally and nationally to allow for meaningful c omparisons of results. Project designs that 11 state success criteria based on the ecological perf ormance of the project rather than project 12 implementation would also aid in comparing the succ ess of similar projects. The most critical 13 need is for monitoring programs that collect pre-pr oject and post-project data for extended 14 periods of time. Granting agencies need to allocate money to monitoring and allow for 15 disbursement of monitoring support during a long pe riod of time (at least 10 years). Such an 16 arrangement would also facilitate the implementatio n of restoration projects at the watershed 17 scale. The present study and a companion study Alexander and Allan (2006) (Alexander and 18 Allan 2006) confirm what has long been speculated. A great dea l of stream restoration is 19 occurring, at considerable expense, and few project s are being monitored to effectively evaluate 20 ecological success. More detailed and standardized reporting restoration project outcomes is a 21 critical need to further the science of ecological stream restoration in the upper midwest region 22 and worldwide. 23 He et al. (2009) He et al

. (2009) applied a depth-averaged two-dimensional model to simulate the 24 effect of large wood structures (LWS) on flow, sedi ment transport, bed change, and fish habitat 25 in a deeply incised sharp bend in the Little Topash aw Creek, North Central Mississippi. 26 Hydrodynamic simulations showed that the flow was r etarded by the large wood matrices along 27 the outer bank and accelerated in the main channel, thus causing deposition along the outer bank 28 and erosion in the main channel, consistent with fi eld observations. Effects on fish habitat were 29 quantified using two approaches. Habitat evaluation s using kinetic energy and circulation metrics 30 indicated that LWS only slightly increased the dive rsity of physical conditions. Weighted usable 31 areas (WUA) for two fish species, blacktail shiner ( Cyprinella venusta ) and largemouth bass 32 (Micropterus salmoides ), were computed using hydrodynamic simulations of three discharges 33 before and after the LWS construction and habitat p reference curves for depth and velocity. The 34 results show that the values of WUA for both fish s pecies were increased after LWS installation 35 at all three discharges. Application of LWS improve d the quantity and quality of fish habitats. 36 Habitat evaluations based on computation of WUA wer e more sensitive to the influence of LWS 37 than metrics based on velocity gradients. 38 The effects of upland disturbance and in-stream res toration on hydrodynamics and ammonium 39 uptake in headwater streams was studied by Roberts et al. (2007) Roberts (2007), who found that 40 the delivery of water, sediments, nutrients, and or ganic matter to stream ecosystems was strongly 41 influenced by the catchment of the stream and can b e altered greatly by upland soil and 42 vegetation disturbance. Upland disturbance did not appear to influence stream hydrodynamics 43 strongly, but it caused significant decreases in in -stream nutrient uptake. In October 2003, coarse 443/15/20 2

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Chapter 7. Hydromodification 50 woody debris (CWD) was added to one-half of the stu dy streams (spanning the disturbance 1 gradient) in an attempt to increase hydrodynamic an d structural complexity, with the goals of 2 enhancing biotic habitat and increasing nutrient up take rates. CWD additions had positive short3 term (within 1 mo) effects on hydrodynamic complexi ty (water velocity decreased and transient 4 storage zone cross-sectional area, relative size of the transient storage zone, fraction of the 5 median travel time attributable to transient storag e over a standardized length of 200 m, and the 6 hydraulic retention factor increased) and nutrient uptake (NH 4 þ uptake rates increased). The 7 results of this study suggest that water quality in streams with intense upland disturbances can be 8 improved by enhancing in-stream biotic nutrient upt ake capacity through measures such as 9 restoring stream CWD. 10 Mulholland et al. (2008) found that on a per area b asis, nitrogen ( N ) removal is important both in 11 stream channels and riparian buffers. Because N rem oval rates are site and time specific, it is 12 difficult to predict the effectiveness of differentrestoration approaches. This study also suggests 13 that clarifying how stream restoration influences N removal will require an evaluation of 14 restoration projects within different landscape con texts that employs the approaches they 15 suggest, both alone and in concert. Approaches shou ld therefore be implemented as adaptive 16 management experiments rather than as solutions to N loading issues, unti l the actual N removal 17 capacity of such projects can be ascertained. Moreo ver, evaluating the ability of current methods 18 to measure the effectiveness of restoration, along with conceptualizing and implementing new 19 methods, is critical to understanding of how restor ation affects N removal. 20 The degradation of inland aquatic habitats caused b y decades of human activities has led to 21 worldwide efforts to rehabilitate freshwater habita ts for fisheries and aquatic resources. Roni et 22 al. (2008) Roni et al

. (2008) reviewed published evaluations of stream rehabilit ation techniques 23 from throughout the world, including studies on roa d improvement, riparian rehabilitation, 24 floodplain connectivity and rehabilitation, in-stre am habitat improvement, nutrient addition, and 25 other, less-common techniques. They summarize curre nt knowledge about the effectiveness of 26 these techniques for improving physical habitat and water quality and increasing fish and biotic 27 production. Their review of 345 papers on effective ness of stream rehabilitation techniques 28 indicates that some techniques, such as reconnectio n of isolated habitats, rehabilitation of 29 floodplains, and placement of in-stream structures, have proven to be effective for improving 30 habitat and increasing local fish abundance under m any circumstances. Techniques for restoring 31 the natural processes that create and maintain habi tats, such as riparian rehabilitation, sediment 32 reduction methods (road improvements), dam removal, and restoration of floods, have also 33 produced encouraging results, but it might take years or decades before a change in fish or other 34 biota is evident, and little or no long-term monito ring of these techniques has been conducted. 35 Their review emphasizes the need for adequate asses sment of watershed processes and factors 36 limiting biotic production, consideration of upstre am or watershed

- scale factors that influence 37 the outcome of reach-scale or localized rehabilitat ion projects, and monitoring and evaluation of 38 adequate temporal and spatial scales. 39 Despite locating 345 studies on effectiveness of stream rehabilitation, firm conclusions about 40 many specific techniques were difficult to make bec ause of the limited information provided on 41 physical habitat, water quality, and biota and because of the short duration and limited scope of 42 most published evaluations (Roni et al. 2008). (Roni et al

. 2008)

. Reconnection of isolated 43 habitats, floodplain rehabilitation, and in-stream habitat improvement have, however, proven 443/15/20 2

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Chapter 7. Hydromodification 51 effective for improving habitat and increasing loca l fish abundance under many circumstances. 1 Techniques such as riparian rehabilitation, road im provements (sediment reduction), dam 2 removal, and restoration of natural flood regimes h ave shown promise for restoring natural 3 processes that create and maintain habitats, but no long-term studies documenting their success 4 have yet been published. Their review demonstrates that the failure of many rehabilitation 5 projects to achieve objectives is attributable to i nadequate assessment of historic conditions and 6 factors limiting biotic production; poor understand ing of watershed-scale processes that 7 influence localized projects; and monitoring at ina ppropriate spatial and temporal scales. They 8 suggest an interim approach to sequencing rehabilit ation projects that partially addresses these 9 needs through protecting high-quality habitats and restoring connectivity and watershed 10 processes before implementing in-stream habitat imp rovement projects. 11 Key research and monitoring priorities include exam ination of most techniques in areas other 12 than the United States and Canada, where most research has occurred. Additional research on in13 stream habitat enhancement structures is needed in other parts of the world, but such techniques 14 have been extensively examined in the western and m idwestern United States and in Canada. 15 Examination of the effectiveness of riparian, road, and floodplain rehabilitation techniques in 16 restoring watershed processes (i.e., delivery of wo od, water, and sediment) and biota is needed in 17 all geographic areas. Finally, few studies have con ducted examinations at a sufficiently broad 18 scale for determining effects of individual or mult iple projects on an entire watershed or fish 19 population. This is clearly one of the most pressin g research needs and is probably attainable 20 with recent technological advances in remote sensin g and fish tagging. 21 Stream restoration, or more properly rehabilitation , is the return of a degraded stream ecosystem 22 to a close approximation of its remaining natural p otential. Many types of practices (dam 23 removal, levee breaching, modified flow control, ve getative methods for streambank erosion 24 control, and such) are useful, but Shields et al. (2003) Shields et al

. (2003) focuses on channel 25 reconstruction. A tension exists between restoring natural fluvial processes and ensuring stability 26 of the completed project. Sedimentation analyses ar e a key aspect of design since many projects 27 fail because of erosion or sedimentation. Existing design approaches range from relatively 28 simple ones based on stream classification and regi onal hydraulic geometry relations to more 29 complex two- and three-dimensional numerical models . Herein an intermediate approach 30 featuring application of hydraulic engineering tool s for assessment of watershed geomorphology, 31 channel forming discharge analysis, and hydraulic a nalysis in the form of one-dimensional flow 32 and sediment transport computations is described. 33 Although the number and scope of stream restoration projects are increasing, designs for these 34 projects are often weak in hydraulic engineering. T his paper represents an attempt to outline 35 acceptable standards for hydraulic design for chann el reconstructions. All stream restoration 36 projects require some level of sedimentation analys is to reduce the risk of undesirable outcomes. 37 More powerful, user-friendly software tools are nee ded for this type of work. Sensitivity analysis 38 and expert advice should be integral parts of such software. More accurate and robust flow 39 resistance and sediment transport relations are nee ded. Ideally, tools for analyzing habitat issues 40 should smoothly interface with those for flow and s ediment transport. Because of the unorthodox 41 nature and relatively high level of uncertainty sur rounding stream restoration projects, 42 involvement by the hydraulic designer should contin ue through the implementation phase, and a 43 monitoring program should be included in project pl ans. 443/15/20 2

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Chapter 7. Hydromodification 52 Streambank erosion is often the dominant source of sediment leaving modified watersheds. Mass 1 failure of high, steep banks is one of the most ser ious forms of streambank erosion. The risk of a 2 given bank experiencing mass failure is a function of bank height, angle, and soil strength, which 3 is governed by soil moisture. Two methods for bank dewatering were tested by Shields et al. 4 (2009) Shields et al

. (2009) in adjacent sections of streambank bordering a dee ply incised channel 5 in northern Mississippi: a low-cost pump system andsubsurface horizontal drains. Pore water 6 pressures (both positive and negative pressures, or matric suction) were continuously monitored 7 for 2 years at the pumped site, at an adjacent untr eated control section, and for 1 year at the site 8 stabilized with horizontal drains. Resulting data w ere used to calculate a time series of the factor 9 of safety using a computer model. Over the course o f two wet seasons, average bank retreats for 10 the control and pumped plots were 0D43 and 0D21 m, respectively. More limited monitoring 11 revealed that the site with passive drains retreate d about 0D23 m. At the pumped site pore water 12 pressure was 3–4 kPa lower than at the control site during the most critical periods. Accordingly, 13 computed factors of safety were above the failure t hreshold at the pumped site, but fell below 14 unity at the control site on 11 occasions over the period of observation. Similarly, the drained site 15 displayed generally lower pore water pressure and h igher safety factors except for two events 16 when drains were evidently overwhelmed with the vol ume of local surface and subsurface flows. 17 These results suggest, but do not prove, that bank dewatering promoted lower rates of bank 18 retreat and higher levels of stability since the th ree sites had slight differences in soils, geometry 19 and boundary conditions. Initial cost of the dewate ring treatments were significantly less than 20 orthodox bank stabilization measures, but operation and maintenance requirements could be 21 greater. 22 Observed bank retreat was much greater during the f irst wet season than during the second, even 23 though more rainfall occurred during the second wetseason (Pezeshki et al

. 2007). During the 24 first wet season, which was colder as well as drier , freeze–thaw action might have primed the 25 bank for subsequent mass failure by opening vertica l cracks extending from the floodplain 26 surface into the upper bank. Sloughing associated w ith freeze–thaw and mass failures during the 27 first year produced material that accumulated at th e bank toes, reducing the bank angles and 28 perhaps increasing stability. For stability modeling modelling , the initial bank profiles were used 29 for the entire 2-year simulation, leading to an und erestimation of stability in the second year. 30 Evidently freeze–thaw processes play a role in bank stability even in the relatively mild climate 31 of northern Mississippi, and these processes are pa rtially addressed by dewatering. The 32 effectiveness of freeze–thaw cycling depends on an adequate moisture supply to form ice 33 crystals and thus dewatering should retard freeze–t haw to some degree. Also, because of the high 34 specific heat capacity of water, changes in soil mo isture affect how rapidly soil temperature 35 changes. 36 Differences in the volume of water discharged by th e drains and pumps as well as the differences 37 among the four pumps suggest that movement of groun dwater through the site was 38 heterogeneous, probably as a result of the lenses o f coarser and finer bed material that compose 39 the bank materials and the presence of macropores (Wilson et al. 2008). ( Wilson et al

. 2007). As 40 noted above, the local topography and a shallow wat erway directed more surface runoff toward 41 the drained site than the other two sites. Differen ces in surface soil were also observed, 42 particularly in regard to dry season pore water pre ssure at a depth of 0D30 m. They ascribe these 43 differences primarily to differences in soils and l ocal hydrology instead of dewatering treatment 44 because pumps and drains likely had little impact o n soil moisture this far above the water table. 453/15/20 2

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Chapter 7. Hydromodification 53 In addition, at 0D30 m both plots responded to near -surface fluxes of rainfall, drainage and 1 evapotranspiration rather than movements of water d eeper in the bank profile. Clearly, precise 2 comparison of the two methods of bank dewatering is not possible because of the site-specific 3 conditions at each plot, but this is typical of fie ld demonstrations as opposed to carefully 4 controlled but less realistic laboratory experiment s. 5 Because shallow soil moisture (0D30 m) was not resp onsive to pumping, and since pumping 6 occurred during the wetter winter and early spring months when vegetation was dormant, 7 impacts of bank dewatering on vegetation were likel y slight, and none were visually observed. 8 Bank vegetation is desirable at most sites for aest hetic, environmental and stability reasons and 9 impacts of dewatering on vegetation should be consi dered when such a project is planned. Site 10 soils, hydrology and geometry will interact with th e local plant community in site-specific ways. 11 However, the main effects of correctly designed ban k dewatering will generally be beneath the 12 root zone, as for their site. 13 The dewatered plots experienced bank retreat rates that were about half as great as the control 14 plot rate. However, definite linkage between dewate ring and bank retreat suppression would 15 require multiple study sites and careful accounting for site differences in soils, groundwater 16 movement, bank geometry and chemistry. Lack of repl ication was a fundamental limitation of 17 this study. Bank retreat rates show great spatial v ariation when measured at smaller scales, and 18 more sites would be required to address this source of variation. For example, Shields et al. 19 (2004) reported results of surveys of 38 cross-sect ions along a 2 km reach of Little Topashaw 20 Creek that encompassed the sites studied herein. Th e standard deviation of bank retreat for a 21 given year was 1D5 to 3D0 times the annual mean. Re treat rates for the plots are comparable if 22 site characteristics are carefully considered. Alth ough the plots were located at different 23 positions along the outside of the creek meander be nd(Figure 2) , removal of failed material from 24 bank toes by fluvial action was not a significant e rosion driver during the study period—in fact, 25 there was some deposition in the toe areas adjacentto the plots as revealed in crosssection 26 surveys summarized by Shields et al. (2004). Higher safety factors observed for the drained site 27 were partially due to more gradual bank slope there , and the lack of pre-treatment data for that 28 site made it impossible to conduct the kind of stat istical tests that were done for the pumped site. 29 Therefore use of passive drains was not shown to ha ve an effect on bank retreat, although there 30 were promising indications that drainage could impr ove bank stability under some conditions. It 31 is notable that the failure events detected by the time series of computed safety fac tor (Figure 4E, 32 Table IV) show lower minima for the drained plot than for the other treatments. These minima 33 suggest that during certain hydrologic conditions t he drains were simply overwhelmed with 34 surface and subsurface flow, greatly increasing por e water pressure at key depths. 35 Performance of the drains could have been improved by modifying drain design parameters 36 (depth and spacing) using better information regard ing soil permeability and hydrologic loading 37 than we had available. Both dewatering treatments were relative ly inexpensive compared with 38 other methods of bank stabilization; total initial costs were $1200 and $370 for the pumped and 39 drained plots, respectively (year 2000 dollars). Ea ch plot stabilized about 30 m of bank at a cost 40 of $40 per meter for the pumped plot and $12 per me ter for the drained plot. This compares with 41 costs of approximately $300/m for stabilization usi ng re-grading and riprap, though there are 42 recurrent costs associated with maintenance for bot h dewatering systems. Bank dewatering can 433/15/20 2

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Chapter 7. Hydromodification 54 be practical to protect critical infrastructure andprovides a potential means of temporarily 1 stabilizing a bank while vegetation is becoming est ablished. 2 The WVCA project manager designed and installed a 1 .5-acre buffer along Links Run. The 3 buffer was designed to enhance wildlife and demonstrated the feasibility of allowing the 4 landowner to plant the trees himself while using th e cost-share rate for larger and better tree 5 stock. Two-hundred linear feet of streambank was pr otected with this plan. Nutrient management 6 planning was a component of this project as well. I n March the finishing touch was put on the 7 first streambank stabilization demonstration projec t completed in 2008 with the establishment of 8 a six acre woody buffer. Over twelve-hundred willow s, dogwoods and other appropriate 9 streamside trees and shrubs were planted at the sit e. BEHI surveys showed that 24 tons of 10 sediment are being eroded from the site post construction. This is contrary to the 793 tons being 11 lost annually before implementation. 12 Lost River load reductions Wildlife Buffer Plan (WB P) vs. implemented 13
Pollutant WBP reductions Estimated reductions % Reductions Nitrogen (lbs/yr) 29,954 1,230 4.11% Phosphorus (lbs/yr) 2,700 4,739 175.54% Sediment (tons/yr) 5,300 769 14.51% Fecal coliform CFUs/yr 2.39E+17 2.14E+14 0.09% 14

15 A second bioengineering streambank stabilization pr oject was completed. In it, 250 feet of 16 eroding streambank was stabilized using bank-slopin g, bio-engineering products and stabilizing 17 toe of slope with rock. The intent of this project was to use low-cost stream restoration 18 techniques versus more costly natural stream restor ation or riprap. After stabilization, 19 streambank exclusion and pasture division fencing w as installed allowing 22 livestock rotation, 20 the estimated fecal reduction is 5.62 x 10^14 cfu/y ear. A nutrient management plan was 21 developed that managed 1,230.3 pounds of N and 4,73 9,128 pounds of P. 22 In addition to the WVCA streambank projects, NRCS h as installed 11,840 feet of stream 23 exclusion fencing. Over 3000 feet of the fencing wa s used to protect 6.3 acres of new woody 243/15/20 2

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Chapter 7. Hydromodification 55 riparian buffers. Outreach is an important componen t of the project, presentations were made to 1 reach 78 people and site tours were given for the d irector of the Chesapeake Bay Program, 2 representatives of Senator Robert Byrd and 23 other agricultural officials. Working with the 3 Baker High School, an Earth Team Volunteers group w as established to support the efforts. 4 These volunteers joined with West VirginiaWV Division of Natural Resources, Baker Run 5 Conservation Society, and USDA NRCS to electroshock in Bear’s Hell Run for biomass and 6 species present. 7
Lost River WBP implementation 8

BMP Units Units planned Units

installed %

Goal Land retirement Acres 500 0.0% Animal waste facility Structures 13 1 7.7% Tree planting Acres 50 0.0% Nutrient management Acres 500 0.0% Off-stream watering w/ fencing Units 10 3 30.0% Off-stream watering w/ fencing and rotational grazi ng Units 20 1 5.0% Riparian buffers Acres 100 28 28.0% Natural stream restoration Linear feet 10,000 1,750 17.5% Totals 11,193 1,783 15.9% 9

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Chapter 7. Hydromodification 56 The Mill Creek watershed headwaters are in Virginia , but most of Mill Creek is in the 1 southeastern part of Berkeley County. It is 14.5 mi les long (one mile of which is in Virginia), 2 and its watershed covers 29.75 square miles. Mill C reek and Torytown Run are on the 303(d) list 3 for biological impairment, with organic enrichment and sedimentation determined to be the 4 biological stressors. These two streams are listed for fecal coliform impairment as well. 5 Therefore, Mill Creek and Torytown Run received TMD L allocations for sediment and fecal 6 coliform. Sylvan Run is listed for biological impai rment only, and the biological stressor is 7 sedimentation. Therefore, Sylvan Run received a sed iment TMDL. Two projects are focusing on 8 Mill Creek, the Conley Natural Stream Design Projec t funded from FY 2006 319 funds and the 9 Mill Creek Project using FY 2009 319 funds. Only th e FY 06 funds were actually available 10 during FY 2009; therefore, only the Conley Project was implemented. 11 Bukaveckas (2007) Bukaveckas ( 2007) studied the interplay between hydrogeomorphic feat ures 12 and ecosystem processes within designed channels. W ater velocity, transient storage, and 13 nutrient uptake were measured in channelized (prere storation) and naturalized (postrestoration) 14 reaches of a 1-km segment of Wilson Creek (Kentucky ) to assess the effects of restoration on 15 mechanisms of nutrient retention. Stream restoratio n decreased flow velocity and reduced the 16 downstream transport of nutrients. Median travel ti me was 50 percent greater in the restored 17 channel because of lower reachscale water velocity and the longer length of the meandering 18 channel. Transient storage and the influence of tra nsient storage on travel time were largely 19 unaffected except in segments where backwater areas were created. First order uptake rate 20 coefficients for N and P were 30- and 3-fold higher (respectively) within the restored channel 21 relative to its channelized state. Changes in uptak e velocities were comparatively small, 22 suggesting that restoration had little effect on bi ochemical demand. Results from this study 23 suggest that channel naturalization enhances nutrie nt uptake by slowing water velocity. 24 Klocker et al. (2009) Klocker et al

. (2009) quantified nitrate uptake in two restored and two 25 unrestored streams in Baltimore, Maryland, using ni trate additions, denitrification enzyme 26 assays, and a 15N isotope tracer addition in one of the urban restored streams, Minebank Run. 27 Restoration included either incorporation of stormw ater ponds below a storm drain and catch 28 basins to attenuate flow or hydrologic reconnection of a stream channel to its floodplain. Stream 29 restoration was conducted for restoring aging sanit ary and bridge infrastructure and introducing 30 some stormwater management in watersheds developed before current regulations. 31 Denitrification potential in sediments was variable across streams, whereas nitrate uptake length 32 appeared to be significantly correlated to surface water velocity, which was low in the restored 33 streams during summer baseflow conditions. 34 Schwartz and Herricks (2007) Schwartz et al

. (2007) evaluated pool-riffle naturalization 35 structures on habitat complexity and the fish commu nity in an urban Illinois stream. A 0.62-km 36 reach of the North Branch of the Chicago River in N orthbrook, Illinois. Initial surveys of channel 37 morphology, habitat and biota identified poor pool- riffle bed structure and fish biodiversity, 38 which became the basis for research and developmentof a pool-riffle structure specifically 39 designed for constrained, low-gradient channels. Habitat and fish surveys were conducted pre40 and post-construction. The project improved mesohab itat structure, and fish abundance, and 41 biomass and diversity were greater for 2 years foll owing construction (2002–2003) compared to 42 3 years before construction (1999–2001). However, t he improved fish metrics were in the low 43 range when compared to rural streams in the same ec oregion, and the fish community consisted 443/15/20 2

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Chapter 7. Hydromodification 57 primarily of tolerant, slow-water species. Absent w ere intolerant and riffle dwelling species, such 1 as insectivorous cyprinids and darters. Assessing p re- and post-project ecological condition and 2 using species information provided a basis for ecol ogically informed design and expanded our 3 understanding of the limitations to restoring urban streams. 4 The pre-design assessment of habitat and fish ident ified an urban channel with limited deep pool 5 habitat consisting mostly of glide-riffle mesohabit at structure, and poor fish community 6 structure. Identification of the single area of hig h fish abundance and biomass at Shermer Road 7 suggested that increasing the number and depth of p ools was a critical design criterion for the 8 project. Pre-project assessments for habitat and bi ota have been shown useful for overall project 9 appraisal (Charbonneau and Resh 1992; Purcell et al . 2002). However, pre-design assessments in 10 these projects relied on qualitative habitat survey s and did not specifically guide the in-channel 11 design analysis supports the view that a broader ex amination of the stream ecosystem and 12 watershed-derived stressors is necessary to advance our restoration science. Important research 13 questions on improving the biological integrity of urban streams remain, such as (1) can critical 14 ecological processes be restored by in-channel, rea ch-scale projects and (2) how can watershed15 scale restoration be achieved by multiple reach-sca le projects. The second question should 16 consider what type of habitat enhancement, how manystructures and where they are placed in 17 the watershed. But more importantly, it must acknow ledge or address the persistent hydrological 18 and ecological stressors. Restoration practitioners and academics alike are interested in better 19 understanding the ecological limitations to restori ng urban watersheds (Palmer et al. 2005; 20 Gillilan et al. 2005), and how to rehabilitate the lost ecological processes (Jannsson et al. 2005). 21 The availability of quality mesohabitat structure w ill be a key element to any restoration 22 initiative, as suggested by the more robust fish co mmunity developed after constructing the 23 Northbrook project. However, improvements in waters hed-scale restoration initiatives that better 24 integrate stormwater programs with in-channel proje cts are seriously needed (Urbonas 2001). 25 Restoration challenges are many in urban streams, w ith streams physically constrained by 26 development and biota impaired by multiple stressor s, but advances in restoration approaches 27 can be achieved by baseline habitat and biota asses sments, new design development integrated 28 with assessments, effective project monitoring and improved watershed management. 29 Kuhnle et al. (2008) Kuhnle (2008) studied the effects of conservation practices, suc h as enrolling 30 erodible lands in the Conservation Reserve Program and in-stream grade stabilization structures 31 in the Goodwin Creek Experimental Watershed in nort h Mississippi. The study found that mean 32 sediments yields would increase from 15 percent to over 200 percent depending on location in 33 the watershed, if in-channel structures were not pr esent. The combined effect of the grade34 control structures and the change of lands because of CRP-enrollment was a reduction in 35 sediment yields by 78 percent near the outlet of th e watershed. 36 Increased delivery of N nitrogen because of urbanization and stream ecosystem degra dation is 37 contributing to eutrophication in coastal regions o f the eastern United States according to 38 Kaushal et al. (2008) who tested whether geomorphic restoration involving hydrologic 39 reconnection of a stream to its floodplain could increase rates of denitrification at the riparian40 zone–stream interface of an urban stream in Baltimo re, Maryland. Rates of denitrification 41 measured using in situ 15N tracer additions were sp atially variable across sites and years and 42 ranged from undetectable to .200 lg N (kg sediment) . Concentrations of nitrate-N in groundwater 43 and stream water in the restored reach were also si gnificantly lower than in the unrestored reach, 443/15/20 2

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Chapter 7. Hydromodification 58 but this might have also been associated with diffe rences in sources and hydrologic flow paths. 1 Riparian areas with low, hydrologically connected streambanks designed to promote flooding 2 and dissipation of erosive force for storm water ma nagement had substantially higher rates of 3 denitrification than restored high nonconnected banks and both unrestored low and high banks. 4 Coupled measurements of hyporheic groundwater flow and in situ denitrification rates indicated 5 that up to 1.16 mg NO3-N could be removed per liter of groundwater flow through one cubic 6 meter of sediment at the riparian-zone–stream inter face over a mean residence time of 4.97 d in 7 the unrestored reach, and estimates of mass removal of nitrate-N in the restored reach were also 8 considerable. Mass removal of nitrate-N appeared to be strongly influenced by hydrologic 9 residence time in unrestored and restored reaches. Results of the study suggest that stream 10 restoration designed to reconnect stream channels w ith floodplains can increase denitrification 11 rates, that there can be substantial variability in the efficacy of stream restoration designs, and 12 that more work is necessary to elucidate which desi gns can be effective in conjunction with 13 watershed strategies to reduce nitrate-N sources to streams. 14

Cost Data 15 The most common restoration activities found by Ale xander and Allan (2006) were the use of 16 sand traps and riprap, and other common activities were related to the improvement of fish 17 habitat. The median cost was $12,957 for projects w ith cost data, and total expenditures since 18 1990 were estimated at $444 million. Over time, the cost of individual projects has increased, 19 whereas the median size has decreased, suggesting t hat restoration resources are being spent on 20 smaller, more localized, and more expensive project s. Only 11 percent of data records indicated 21 that monitoring was performed, and more expensive p rojects were more likely to be monitored. 22 Standardization of monitoring and record keeping an d dissemination of findings are urgently 23 needed to ensure that dollars are well spent and re storation effectiveness is maximized. 24 Implications for practice Practice 25

• Stream restoration in the Midwest is increasing; ye t, lack of project documentation and 26 monitoring have inhibited the learning cycle. 27

• Since the early 1990s, total expenditures on streamrestoration in the upperUpper 28 Midwest region are approximately $444 million. 29

• Project goals have emphasized improvements in in-stream habitat, riparian and bank 30 condition, and water quality. 31

• Standardizing Standardization of monitoring and record keeping and dissemination of 32 findings are urgently needed to ensure that dollars are well spent and restoration 33 effectiveness is maximized. 34
Design Guidance and additional info 35 Rosgen, D. 1996. Applied River Morphology. Wildland Hydrology, Pagosa Springs, CO. 363/15/20 2

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Chapter 7. Hydromodification 59 2.2.5.15 Step Pools 1 Description 2 Step pools are rock grade-control structures constr ucted in the stream channel that recreate 3 natural step-pool channel morphology. 4
Application and Purpose 5 Step-pool channels are characterized by a successio n of channel-spanning steps formed by large, 6 grouped boulders called clasts that separate pools containing finer bed sediments. They are 7 constructed in higher gradient channels where a fix ed-bed elevation is required. Step pools are 8 built in series and allow for stepping down the channel over a series of drops. The steps are 9 constructed of large rock with the pools containing smaller rock material. As flow tumbles over 10 the step, energy is dissipated into the plunge pool

. 11 Step-pools can be used to backwater a culvert, prov iding improved fish passage and can be used 12 to connect two reaches with different elevations. 13 Step-pool morphologies are typically associated wit h well-confined, high-gradient channels with 14 slopes greater than 3 percent, having small width-d epth ratios and bed material dominated by 15 cobbles and boulders. Step pools generally function as grade-control structures and aquatic 16 habitat features by reducing channel gradients and promoting flow diversity. At slopes greater 17 than roughly 6.5 percent, similar morphologic units termed cascades spanning only a portion of 18 the channel width are formed in these channel condi tions. 19 Step pools are not generally considered a habitat e nhancement practice. The enhancement 20 potential is in the form of maintaining fish passag e and expanding the total amount of habitat 21 available for fish. 22

Cost Data 23 Construction costs for step pools are highly variab le, depending on the design, size of the stone, 24 availability of materials, and site constraints. 25 Design Guidance and additional info 26 The following documents provide design information and guidance for vanes. 27 Stream Restoration: A Natural Channel Design Handbo ok, prepared by the North Carolina 28 Stream Restoration Institute and North Carolina Sea Grant. 29 http://www.bae.ncsu.edu/programs/extension/wqg/srp/ sr_guidebook.pdf 30 The Virginia Stream Restoration & Stabilization Bes t Management Practices Guide, Department 31 of Conservation and Recreation, Division of Soil an d Water Conservation 2004. 32 http://www.dcr.virginia.gov/soil_and_water/document s/streamguide.pdf 333/15/20 2

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Chapter 7. Hydromodification 60 2.2.5.16 Streambank Dewatering 1 Description 2 Using groundwater level management adjacent to an e roding streambank to lower static water 3 pressure on bank and reduce erosion potential

. 4
Application and Purpose 5 Streambank dewatering is the practice of actively o r passively reducing the static water level 6 immediately adjacent to a streambank with erosion p otential for the purposes of reducing poor 7 water pressure within the streambank. The reduced p ore pressure improves the shear strength of 8 bank soils. As shear strength is one of several gov erning factors for bank failure, a reduction in 9 bank failure rates and potential is expected. 10 Dewatering systems can take several forms. Specific designs which are discussed in the research 11 literature are vertical groundwater wells managed b y an active pumping system and installing 12 horizontal tile drains, which provide passive drain age for the riparian zone. While other 13 dewatering system designs might be possible, no pub lished information on additional methods 14 are available. The location, depth, capacity, and c onfiguration of the dewatering systems vary 15 depending on local conditions, and no published gui dance on streambank dewatering is 16 available. 17 Using streambank dewatering is not widespread. A nu mber of alternative practices are available 18 that might be more suitable for a particular applic ation. Dewatering systems that rely on 19 pumping systems have an inherent long-term maintena nce and operational cost. For those, 20 reasons streambank dewatering might be most appropr iate for short-term use or in areas where 21 grading and practice installation along the bank ar e not possible (such as because of utility 22 conflicts, access constraints, and the like). In ad dition, it is important to note that streambank 23 dewatering can affect riparian habitat condition an d available groundwater for riparian habitat. 24 Where wetlands are present adjacent to the stream, dewatering could affect the wetland 25 condition. 26

Performance 27 Shields et al. (2009) Shields et al

. ( 2009) reported that streambank dewatering resulted in re duced 28 rates of bank erosion on a deeply incised channel i n northern Mississippi (2009) . Pumped and 29 passive drain systems exhibited bank erosion of 0.2 1 m and 0.23 m, respectively, over a 2-period 30 of two wet seasons, while a streambank without dewa tering exhibited erosion of 0.43 m. While 31 reduced bank erosion was observed where streambank dewatering was used, the researches note 32 that at some individual monitoring stations, bank e rosion exceeded control values. 33

Cost Effectiveness 34 While no published cost information is available, Shields et al. (2009) Sheildet al. (2009) report 35 that initial costs of dewatering systems was signif icantly lower than more orthodox bank 36 stabilization measures, while it was acknowledged t hat long term pumping and maintenance 37 costs were neglected. 383/15/20 2

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Chapter 7. Hydromodification 61 2.2.5.17 Vegetated Gabions 1 Description 2 A gabion is a rectangular basket made of heavily ga lvanized wire mesh filled with small to 3 medium size rock. The gabions are laced together an d installed at the base of a bank to form a 4 structural toe or sidewall. Vegetation can be incor porated by placing live branches between each 5 layer of rock filled baskets. The branches take roo t inside the gabions and in the soil behind the 6 structures. Their roots eventually consolidate the structure and bind it to the slope. 7 Application and Purpose 8 The National Management Measures to Control Nonpoint So urces Pollution from 9 Hydromodification document (USEPA published by EPA in 2007 ) contains a chapter on the 10 practice of vegetated gabions. At the time of this writing no additional information is provided 11 pertaining to this practice. For information on the appropriate use and application for vegetated 12 gabions, see the 2007 guide. 13

Cost Effectiveness 14 Vegetated gabions are comparable to vegetated geogr ids and vegetated reinforced soil slope, 15 ranging from $15 to $40 per square foot. Constructi on costs vary with the structure’s design 16 (materials, depth into the streambed, height and wi dth, and such), site access, time of year, 17 degree and type of associated channel redefinition, and equipment and labor rates. 18

2.2.5.18 Vegetated Geogrids 19 Description 20 Vegetated geogrids are the covering of soil with er osion control fabric (geotextile) on the slope 21 of the bank. The erosion control fabric is secured by tucking it into the slope. Live cuttings are 22 placed between the geogrids, and a root structure i s established to bind the soil within and behind 23 the geogrids. The toe of the bank is stabilized by layers of rock on top of the same geotextile 24 fabric. 25
Application and Purpose 26 The National Management Measures to Control Nonpoint So urces Pollution from 27 Hydromodification document (USEPA published by EPA in 2007 ) contains a chapter on the 28 practice of Vegetated Geogrids. At the time of this writing no additional information is provided 29 pertaining to this practice. For information on the appropriate use and application for vegetated 30 geogrids, see the 2007 guide. 31

Cost Data 32 Vegetated geogrids range in cost from $20 to $40 pe r square foot depending on the design and 33 construction techniques (Sotir and Fischenich 2003)

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Chapter 7. Hydromodification 62 2.2.5.19 Vegetated Reinforced Soil Slope (VRSS) 1 Description 2 The vegetated reinforced soil slope (VRSS) soil sys tem is an earthen structure constructed from 3 living, rootable, live-cut, woody plant material br anches, bare root, tubling or container plant 4 stock, along with rock, geosynthetics, geogrids, an d/or geocomposites. 5 Application and Purpose 6 The National Management Measures to Control Nonpoint So urces Pollution from 7 Hydromodification document (USEPA published by EPA in 2007 ) contains a chapter on the 8 practice of Vegetated Reinforced Soil Slopes. At th e time of this writing, no additional 9 information is provided pertaining to this practice . For information on the appropriate use and 10 application for vegetated reinforced soil slopes, s ee the 2007 guide. 11

Cost Data 12 Vegetated reinforced soil slopes structure costs ty pically range from $15 to $35 per square face 13 foot. These prices do not include design, which can be extensive because of the required 14 geotechnical data collection and analysis. Harvesti ng, transportation, handling, and storage of the 15 live-cut branch materials or rooted plants can sign ificantly influence cost, and are included in the 16 above range. 17 Construction costs also vary with the structure’s d esign (materials, depth into the streambed, 18 height and width, etc.), site access, time of year, degree and type of associated channel 19 redefinition, and equipment and labor rates. Instal lation is relatively complex, as it can require 20 large earth-moving machinery. Installation, excavat ion, and soil replacement costs are usually 21 high. 22

2.2.5.20 Weirs 23 Description 24 This is a technique in which boulders or logs are l aced across the channel and anchored to the 25 channel bank and/or bed to check the water and rais e its level for diversion purposes; they are 26 designed to allow overtopping. 27
Application and Purpose 28 Low profile in-stream structures such as vortex roc k weirs and w-weirs are primarily used to 29 create aquatic habitat in the form of scour pools a nd for grade control on incising streams and 30 rivers. Additionally, they are well-suited for chan neling flow away from unstable banks. Weirs 31 are used to collect and retain gravel for spawning habitat, to deepen existing resting/jumping 32 pools; to create new pools above or below the struc ture, to trap sediment, to aerate the water, and 33 to promote deposition of organic debris. 34 There are several types of weirs, but the two most common types for stream restoration are the 35 W-weir and the rock vortex weir. Both types provide grade control and reduce bank erosion. The 36 weirs accumulate sediment behind the weir arms and create a scour pool downstream of the 37 structure. A rock W-weir is a stone structure compo sed of footer and vane rocks and consists of 383/15/20 2

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Chapter 7. Hydromodification 63 four weir arms arranged in a W fashion across the channel. A rock vortex weir con sists of footer 1 and vane rocks, and the form of the rock vortex wei r is parabolic and spans the channel width. 2 The rock vortex weir accumulates sediment behind th e weir arms and creates a scour pool 3 downstream of the structure. 4 Weirs are typically suited for use in moderate to h igh gradient streams. W-weirs are best used in 5 rivers with bankfull widths greater than 40 feet (1 2 meters). Weirs should be avoided in channels 6 with bedrock beds or unstable bed substrates, and s treams with naturally well-developed, pool7 riffle sequences. 8

Cost Data 9 Construction costs for weirs are highly variable, d epending on width of the channel, size of the 10 stone, availability of materials, and site constrai nts. 11 Design Guidance and additional info 12 The following documents provide design information and guidance for vanes. 13 Stream Restoration: A Natural Channel Design Handbo ok, prepared by the North Carolina 14 Stream Restoration Institute and North Carolina Sea Grant. 15 http://www.bae.ncsu.edu/programs/extension/wqg/srp/ sr_guidebook.pdf 16

2.2.5.21 Wing Deflectors 17 Description 18 Wing deflectors are devices made of a variety of ma terials that project outward into the channel 19 from one or both streambanks but do not extend enti rely across the channel. Wing deflectors are 20 especially effective in wide, shallow, low gradient streams to create pools and cover

. 21
Application and Purpose 22 Wing deflectors are designed to deflect flows away from the bank and create scour pools by 23 constricting the channel and accelerating flow. The structures can be installed in series on 24 alternative streambanks to produce a meandering tha lweg and stream diversity. The most 25 common design is a rock and rock-filled log crib de flector structure. The design bases the size of 26 the structure on anticipated scour. These structure s need to be installed far enough downstream 27 from riffle areas to avoid backwater effects that c ould drown out or damage the riffle. This 28 design should be employed in streams with low physi cal habitat diversity, particularly channels 29 that lack pool habitats. Construction on a sand bed stream can be susceptible to failure and 30 should be constructed with the use a filter layer o r geotextile fabric beneath the wing deflector 31 structure (FISRWG 1998). 32 When two wing deflectors are placed opposite each o ther they serve to narrow or constrict the 33 flow of water. The double wing deflector is more of ten used in urban applications as it forces the 34 water toward the center of the channel and deepens the baseflow channel. Double wing 35 deflectors also create an area of increased velocit y between them, enhancing riffle habitat 36 between and just upstream of the structure. This in creased velocity also creates an area of scour, 37 creating pool habitat downstream of the structure. The construction is the same as a single wing 383/15/20 2

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Chapter 7. Hydromodification 64 deflector except that in some instances, a rock sil l at the stream invert can connect the two 1 structures. 2 Both single and double wing deflectors have signifi cant habitat enhancement potential. These 3 structures enhance habitat through pool formation, the narrowing and deepening of the baseflow 4 channel, and the enhancement of riffle habitat. Def lectors protect the bank in the immediate area 5 and provide desirable changes to the stream flow pa tterns. They are relatively easy to construct, 6 inexpensive, easily modified to suit on-site condit ions, and are adaptable for use with other 7 treatments. They are significantly cheaper to insta ll than dam-type structures. They are effective 8 in sections of streams where the banks are too low or too wide for dams. 9 The following limitations apply to stream deflector s: 10

• Deflectors should not be used in unstable streams w hich do not retain a constant planform 11 or are actively incising at a moderate to high rate

. 12

• Deflectors are ineffective in bedrock channels sinc e minimal bed scouring occurs. 13 Conversely, streams with fine sand, silt, or otherw ise unstable substrate should be 14 avoided since significant undercutting can destroy these measures. 15

• Deflectors should not be used in stream reaches whi ch exceed a 3 percent gradient. 16

• Deflectors should not be used in streams with large sediment or debris loads. 17

• Banks opposite these structures should be monitoredfor excessive erosion. 18
Design Guidance and additional info 19 Additional Resources 20 FISRWG (Federal Interagency Stream Restoration Working Gr oup) . 1998. Stream Corridor 21 Restoration: Principles, Processes, and Practices. Federal Interagency Stream Restoration 22 Working Group. 23 http://www.nrcs.usda.gov/technical/stream_restorati on/PDFFILES/APPENDIX.pdf

. 24 Massachusetts DEP. 2006. Massachusetts Nonpoint Sou rce Pollution Management Manual: 25 Wing Deflectors. Massachusetts Department of Enviro nmental Protection, Boston, MA. 26 http://projects.geosyntec.com/NPSManual/Fact%20Shee ts/Wing%20Deflectors.pdf

. 27 Mississippi State University, Center for Sustainabl e Design. 1999. Water Related Best 28 Management Practices in the Landscape: Single Wing Deflector. Prepared for the U.S. 29 Department of Agriculture, Natural Resource Conserv ation Service, Watershed Science 30 Institute. http://www.abe.msstate.edu/csd/NRCS-BMPs/pdf/stream s/bank/singlewing.pdf

. 31 Mississippi State University, Center for Sustainabl e Design. 1999. Water Related Best 32 Management Practices in the Landscape: Double Wing Deflector. Prepared for the U.S. 33 Department of Agriculture, Natural Resource Conserv ation Service, Watershed Science 34 Institute. http://abe.msstate.edu/csd/NRCS-BMPs/pdf/streams/ba nk/doublewing.pdf

. 35
Ohio DNR (Department of Natural Resources) . No date. Ohio Stream Management Guide: 36 Deflectors . Ohio Department of Natural Resources. 37 http://www.ohiodnr.com/water/pubs/fs_st/stfs19.pdf

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Chapter 7. Hydromodification 65 SMRC (Stormwater Manager’s Resource Center) . No date. Stream Restoration: Flow 1 Deflection/Concentration Practices. The Stormwater Manager’s Resource Center. 2 http://www.stormwatercenter.net/Assorted%20Fact%20S heets/Restoration/flow_deflection 3 .htm

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Chapter 7. Hydromodification 66 

## 3 References Appendix A. Sources of Data 1 Ahearn, D.S., R.W. Sheibley, and R. Dalhlgren. 2005 . Effects of river regulation on water 2 quality in the lower Mokelumne River, California. River Research and Applications 3 21(6):651–670. 4 Alexander, G.G., and J.D. Allan 2006). Stream resto ration in the Upper Midwest, USA. 5 Restoration Ecology 14(4):595–604. 6 Alexander, G.G., and J.D. Allan 2007). Ecological s uccess in stream restoration: Case studies 7 from the midwestern United States. Environmental Management 40(2):245–255. 8 Allen, H., and C. Fischenich. 2000. Coir Geotextile Roll and Wetland Plants for Streamb ank 9 Erosion Control . U.S. Army Corps of Engineers, Ecosystem Managemen t and Restoration 10 Ecosystem Research Program, Vicksburg, MS. 11 Blankenship, K. 2009. Living shoreline project prot ects waterfowl habitat. Bay Journal

. 12 Baltimore, MD, Alliance for the Chesapeake Bay. 19: 1. 13 Booth, D.B., J.R. Karr, S. Schauman, C.P. Konrad, S .A. Morley, M.G. Larson, and S.J. Burges. 14 2004. Reviving urban streams: Land use, hydrology, biology, and human behavior. Journal 15 of the American Water Resources Association 40(5):1351–1364. 16 Born, S.M., K.D. Genskow, T.L. Filbert, N. Hernande z-Mora, M.L. Keefer and K.A. White. 17 1998. Socioeconomic and institutional dimensions of dam removals: the Wisconsin 18 experience. Environ Mgt 22:359–70. 19 Brussock, P.P., A.V. Brown, and J.C. Dixon. 1985. C hannel form and stream ecosystem models. 20 Water Resources Bulletin 21:859–866. 21 Bukaveckas, P.A. 2007. Effects of channel restorati on on water velocity, transient storage, and 22 nutrient uptake in a channelized stream. Environmental Science & Technology 41(5):1570– 23 1576. 24 Bushaw-Newton, K.L., D.D. Hart, J.E. Pizzuto, J.R. Thomson, J. Egan, J.T. Ashley, T.E. 25 Johnson, R.J. Horwitz, M. Keeley, J. Lawrence, D. C harles, C. Gatenby, D.A. Kreeger, T. 26 Nightengale, R.L. Thomas, and D.J. Velinsky. 2002. An integrative approach towards 27 understanding ecological responses to dam removal: The Manatawny Creek Study. Journal 28 of the American Water Resources Association 38(6):1581–1599. 29 Chang, H. H. 2008. Case study of fluvial modeling o f river responses to dam removal. Journal of 30 Hydraulic Engineering-ASCE 134(3):295–302. 31 Charbonneau, R., and V.H. Resh. 1992. Strawberry cr eek on the University of California, 32 Berkeley campus: A case history of urban stream res toration. Aquatic Conservation: 33 Marine and Freshwater Ecosystems 2(4):293–307. 343/15/20 2

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Chapter 7. Hydromodification 67 Chesapeake Bay Program. 2009. Bay Barometer: A Heal th and Restoration Assessment of the 1 Chesapeake Bay and Watershed in 2008. EPA-903-R-09- 001. Chesapeake Bay Program, 2 Annapolis, MD. 3 D’Angelo, D.J., S.V. Gregory, L.R. Ashkenas, and J. L. Meyer. 1997. Physical and biological 4 linkages within a stream geomorphic hierarchy: a mo deling approach. N. Am. Benthol. Soc. 5 16(3):480–502. 6 Doyle, M.W., E.H. Stanley, and J.M. Harbor. 2003. H ydrogeomorphic controls on phosphorus 7 retention in streams. Water Resources Research 39(6). 8 Doyle, M.W., E.H. Stanley, C.H. Orr, A.R. Selle, S. A. Sethi, and J.M. Harbor. 2005. Stream 9 ecosystem response to small dam removal: Lessons fr om the Heartland. Geomorphology 10 71(1–2):227–244. 11 FISRWG (Federal Interagency Stream Restoration Work ing Group). 1998. Stream Corridor 12 Restoration: Principles, Processes, and Practices . GPO Item No. 0120-A; SuDocs No. A 13 57.6/2:EN 3/PT.653. Federal Interagency Stream Rest oration Working Group. 14 Frimpong, E.A., J.G. Lee, and T.M. Sutton. 2006. Co st effectiveness of vegetative filter strips 15 and instream half-logs for ecological restoration. Journal of the American Water Resources 16 Association 42(5):1349–1361. 17 Frissell, C.A., W.J. Liss, C.E. Warren, and M.D. Hu rley. 1986. A hierarchical framework for 18 stream habitat classification: viewing streams in a watershed context. Environmental 19 Management

10:199– 214. 20 Gillilan, S., K. Boyd, T. Hoitsma, and M. Kauffman. 2005. Challenges in developing and 21 implementing ecological standards for geomorphic ri ver restoration projects: a 22 practitioner’s response to Palmer et al. 2005. Journal of Applied Ecology 42(2):223–227. 23 Graf, W.L. 2006. Downstream hydrologic and geomorph ic effects of large dams on American 24 rivers. Geomorphology 79(3–4):336–360. 25 Gray, D.H., and R.B. Sotir. 1996. Biotechnical Soil Bioengineering Slope Stabilizatio n: A 26 Practical Guide for Erosion Control . John Wiley & Sons, New York, NY. 27 He, Z.G., W.M. Wu, F.D. Shields Jr. 2009. Numerical analysis of effects of large wood 28 structures on channel morphology and fish habitat s uitability in a Southern U.S. sandy 29 creek. Ecohydrology 2(3):370–380. 30 Jannsson, R., H. Backx, A.J. Boulton, M. Dixon, D. Dugeon, F.M.R. Hughes, K. Nakamura, 31 E.H. Stanley, and K. Tockner. 2005. Stating mechani sms and refining criteria for 32 ecologically successful river restoration: a commen t on Palmer et al. 2005. Journal of 33 Applied Ecology 42(2):218–222. 34 Johnson, P.A., and E.R. Brown. 2000. Stream assessm ent for multicell culvert use. Journal of 35 Hydraulic Engineering , ASCE, 381–386. 363/15/20 2

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