Addressing the Impact of Road-Stream Crossing Structures on the Movement of Aquatic Organisms

Transcription

1 Scott Jackson University of Massachusetts Amherst Addressing the Impact of Road-Stream Crossing Structures on the Movement of Aquatic Organisms

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3 Dams

4 Sub-standard Culverts

5 Excessive Velocities

6 Inlet Drop

7 Outlet Drop (Perching)

8 Insufficient Water Depth

9 Flow Contraction

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11 Micrographia Radu Guiasu Scott Jackson Scott Jackson Micrographia 1999 Joyce Gross Robert Jenkins & Noel Burkhead Barry Wicklow Kenneth Catania

12 Micrographia Micrographia Alan Richmond 1999 Joyce Gross Robert Jenkins & Noel Burkhead Barry Wicklow

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16 Openness

17 721 sq.mi. Source: MA Riverways Program

18 Source: MA Riverways Program

19 Source: MA Riverways Program

20 Source: MA Riverways Program

21 Source: MA Riverways Program

22 River and Stream Continuity Partnership University of Massachusetts Amherst MA Riverways Program The Nature Conservancy River & Stream Continuity Project

23 Objectives of the River/Stream Continuity Project Technical guidance and standards for river/stream crossings Rapid assessment methodology to inventory and evaluate culverts and other stream crossing structures System for prioritizing crossing structures for upgrade or replacement

24 Standards for River & Stream Crossings Two Levels General Optimum

25 General Standards Where: Goals: Fish bearing streams and rivers Fish passage River/stream continuity Some wildlife passage

26 Bridge span preferred General Standards If a culvert then embedded > 2 foot; > 1 foot and 25% for corrugated round culverts Natural bottom substrate within culvert (matching upstream and downstream substrates) Spans channel (1.2 x bankful width) Designed to provide water depths and velocities at a variety of flows that are comparable to those found in upstream and downstream natural stream segments (e.g. low flow channel) Openness ratio > 0.25 (calculated in meters)

27 MA Programmatic General Permit (PGP) New permanent crossings shall conform with the General Standards contained in the March 1, 2006 Massachusetts River and Stream Crossing Standards

28 NWP General Condition 4 Aquatic Life Movements. No activity may substantially disrupt the necessary life-cycle movements of those species of aquatic life indigenous to the waterbody, including those species that normally migrate through the area, unless the activity s primary purpose is to impound water. Culverts placed in streams must be installed to maintain low flow conditions.

29 Bridge

30 Open-bottom Box

31 Open-Bottom Arch

32 Stream Simulation Culvert

33 Stream Simulation Bed Channel cross-section Shoulder (or bankline if continuous) Bankfull Width Height Channel margins Initial low flow channel 1 ~ 5 Rock Band 10 ft low flow channel

34 Steps Culvert Step boulders simulate natural steps Alluvial bed material mix Profile View Natural steps Bank boulders Plan View

35 Ecosystem Restoration Via Crossing Upgrades Systematic evaluation of river and stream crossings Evaluation of habitat quality and landscape considerations Establish priorities for upgrades Careful design and construction Permitting

36 Highest Quality High Quality General

37 Assessment Field Forms

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40 MA Crossing Structures Scoring System Flow Contraction Y N Inlet Drop Primary Score < 80 = < 6 (5) None (10) Outlet Drop 6 < 6 (5) None (10) Tailwater Armoring Inappropriate or none (0) Substrate Contrasting (5) Comparable (10) Inappropriate or none (0) Substrate Contrasting (5) Comparable (10) Extensive Not Extensive (5) None (10) Secondary Score Physical Barriers Permanent Temporary (5) None (10) Span Scour Pool Large (0) Small (5) None (10) 5 Constricts Channel Active Channel 6 Bankful Channel Channel & Banks Embedded Not Embedded (0) Partially (3) Fully <1 (7) Fully >1 (10) Water Depth Openness Ratio < > 0.75 Openness Ratio < > 0.75 Not Comparable (0) Comparable (10) Water Velocity Height Height Not Comparable (0) Comparable (10) 8 < 6 ft > 6 ft 9 9 < 6 ft > 6 ft 10

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43 Severe barrier Moderate barrier Minor barrier Meets General Stds Meets Optimal Stds

44 Important Considerations for Culvert Replacement/Upgrades Stream channel adjustments and structure stability Upstream head cutting Loss or degradation of upstream wetlands Loss of flood control in developed watersheds

45 Long profile with notes of possible changes in the life of the project. Scour pool and tailout Road crossing Potential slope failures and aggradation Backwater deposition Range of possible future profiles Alluvial scour depth of existing channel Bedrock probed Exposed bedrock limits incision and scour Temporary debris jams

46 Scour Pool vs. Incised Channel Original Channel Grade Outlet Scour Incised Channel Original Channel Grade Incised Channel Grade Nick point-evaluate losses

47 Headcut issues Bed material Wynoochee trib Culvert replaced

48 Confined Unconfined

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