STREAM RESTORATION PURPOSE, PRACTICE, AND METHODS. By Marcus Rubenstein, CPESC

Transcription

1 STREAM RESTORATION PURPOSE, PRACTICE, AND METHODS By Marcus Rubenstein, CPESC

2 WHAT IS STREAM RESTORATION? The return of a stream s lost natural functions, usually resulting from watershed alterations, such as development and agricultural practices.

3 THE DRIVING FORCE CLEAN WATER ACT (CWA) Objective: to restore and maintain the chemical, biological, and physical integrity of the nation s waters

4 WHEN IS STREAM RESTORATION PROMPTED? Under the CWA, there are two major programs that promote improved stream health and stream restoration. SECTION 404 SECTION NPDES Provides for the use of compensatory mitigation to offset unavoidable impacts to aquatic resources. MITIGATION Prompts MS4 permitted communities to perform watershed improvements, i.e. stream restoration as part of a larger strategy to implement total maximum daily loads (TMDLs). RESTORATION

5 SECTION 404 Issues permits for unavoidable impacts to streams, wetlands, lakes, and other aquatic recourses. MITIGATION: Avoidance Minimization Compensation COMPENSATORY MITIGATION: Mitigation Bank In-Lieu Fee Custom Mitigation Site

6 SECTION NPDES The National Pollutant Discharge Elimination System (NPDES) permit program controls water pollution by regulating point sources that discharge pollutants into waters of the United States. An MS4 is a conveyance or system of conveyances that is: Owned by a state, city, town, village, or other public entity that discharges to waters of the U.S.; Designed or used to collect or convey stormwater (including storm drains, pipes, ditches, etc.). Conditions of MS4 Discharge Permits include the implementation of water quality and watershed protection elements, including the restoration of ecologically sensitive areas that provide water quality benefits and serve critical watershed functions. These areas may include, but are not limited to; riparian corridors, headwater streams, floodplains and wetlands.

7 OTHER STREAM RESTORATION EFFORTS? Section 319(h) Grants (CWA) Section 206 Grants (USACE) Academia Private Citizens

8 WHAT DO WE ALREADY KNOW ABOUT STREAMS (in the context of Stream Restoration)? The WORK of a stream is to move water and to move sediment.

9 WHAT DO WE ALREADY KNOW ABOUT STREAMS (in the context of Stream Restoration)? Streams seek a state of Dynamic Equilibrium Natural Stream Channel Stability is achieved when a stream has a stable cross-sectional dimension, horizontal alignment [pattern], and vertical alignment [profile]. Cross-Section Pattern Profile

10 WHAT DO WE ALREADY KNOW ABOUT STREAMS (in the context of Stream Restoration)? Dynamic Equilibrium is a function of the work of a stream and is associated with a channel and a flood prone area. Bankfull Discharges forms the main channel. Stream channels meander in a predictable manner.

11 So Sediment > Flow Flow > Sediment Aggredation Degradation A good place to start when choosing a restoration site.

12 Natural Stream Design The Rosgen Method System of Stream Classification 1. Broad Morphological Characterization 11 Valley Types 8 Stream Types

13 Natural Stream Design The Rosgen Method System of Stream Classification 2. Description of Stream Type 94 Stream Variations Streambank Erosion Potential Influence of Riparian Vegetation Recovery Potential

14 Stream Restoration Methodology Natural Stream Design The Rosgen Method System of Stream Classification 3. Stream Condition Assesses the causes and the extent of instability in the stream and its watershed. Departure Analysis. Comparison to reference channel. 4. Field Verification Sediment transport Bank erosion rates Aggradation/degradation Evaluates restoration efforts and repair effectiveness by stream type.

15 Stream Restoration Methodology Priority 1 Restoration/Relocation involves excavation of a stable Rosgen Class C or E stream channel, on previous floodplain, to replace an entrenched Rosgen Class G or F stream channel. Priority 2 Restoration involves establishment of a stable Rosgen Class C or E stream channel and floodplain, at the current or higher (but not original) channel elevation, to replace an entrenched Rosgen Class G or F stream channel. Priority 3 Restoration involves converting to a new stream type without an active floodplain but containing a floodprone area (example, Rosgen Class G to B stream, or Rosgen Class F to Bc). Priority 4 Restoration involves stabilization of an incised stream channel in place using instream structures and bioengineering. Typical instream structures include crossvanes, J-hook vanes, other rock vanes, single and double wing deflectors, and root wads that divert the thalwag from the streambank and/or absorb water energy. Bioengineering techniques include fascines, branch packing, brush mattresses, live cribwalls, tree revetments, or coir fiber logs, supplemented with use of erosion control matting and live staking for long term stability.

16 Stream Restoration Activities Understand your stream and what it needs Developed watersheds with straitened / incised channels recovery Developing watersheds with increased runoff degradation Construct a channel that will accommodate current and future processes Bed load movement Restoring riffles and pools Reducing bank stress Providing a floodplain Reducing flooding Improving water quality If you don t understand your problem, hire someone who does!

17 Stream Restoration and Water Quality Reconnect the stream to its floodplain: Flood attenuation Expanded flood prone area Infiltration (saturated soils) Re-engage floodplain wetlands (chemical processes) Slow velocity

18 Stream Restoration and Water Quality Offline Water Quality BMP s are an important component in urban settings. i.e. Stormwater Wetlands, Bioretention, Sand Filters etc Increased and diverse riparian species in buffer. Increased habitat in stream. University of Maryland study conducted an assessment of nitrogen level impacts on stream restoration sites: Reconnected restored streams. Double nitrogen removal rates vs. un-restored, disconnected reaches. 40% less nitrogen in ground water. Significantly less nitrogen levels in the stream. This assessment is relevant to the benefits of restoration as our nation s infrastructure gets repaired.

19 Know you Project Footprint. Planning and Permitting Understand the legal and permitting requirements. NW27 NPDES LDA Floodplains Cultural Resources Endangered Species Contamination Know construction needs beyond just working in the stream. Access Staging Stockpiles Crossings and drainage E&SC Easements

20 WHITE CREEK MITIGATION BANK CASE STUDY 80-Acres - Monroe County Forests 40-acres Pasture 28-acres Fallow Field 4-acres Farm Pond 3-acres Wetlands 5-acres White Creek and 5 tributaries Upper Ocmulgee Watershed ( ) 1.8 square mile watershed Degraded from livestock activities Proximity to Atlanta

21 WHITE CREEK MITIGATION BANK CASE STUDY Baseline studies taken in 2005 Soils Hydrology Geomorphology of White Creek and 6 tributaries fish / macro / water quality Riparian vegetation Riparian wildlife Reference stream data Long Branch (Trib of Ocmulgee River) Similar watershed size Valley types Stream types

22 WHITE CREEK MITIGATION BANK CASE STUDY Approved as a commercial mitigation bank in early Construction from May - August, ½ Mile on White Creek (P1, P2, RR) feet of other tributaries (P1, P2, RR). G and F Channel C and E Channel. Seven years of monitoring and reporting (Success Criteria).

23 WHITE CREEK MITIGATION BANK CASE STUDY P1

24 WHITE CREEK MITIGATION BANK CASE STUDY P1

25 WHITE CREEK MITIGATION BANK CASE STUDY P2

26 WHITE CREEK MITIGATION BANK CASE STUDY P1

27 WHITE CREEK MITIGATION BANK CASE STUDY P1

28 WHITE CREEK MITIGATION BANK CASE STUDY PUBLISHED ARTICLE BANKING ON NATURAL FIBERS LAND AND WATER MAGAZINE JAN/FEB 2007

29 CITY OF DECATUR GREENSPACE ENHANCEMENT CASE STUDY Middle Chattahoochee River Basin ( ) Glen Creek South Fork Peachtree Creek (TMDL Fishing) 120-acre watershed Degraded from Urban Runoff and Invasive Species Highly Urban Setting Draining Portions of Downtown Decatur The watershed is entirely built-out, with contributing drainage from single-family lots, commercial facilities, and portions of downtown. This creates a flashy hydrograph that leads to high shear stress for a short duration during the typical Atlanta thunderstorm.

30 CITY OF DECATUR GREENSPACE ENHANCEMENT CASE STUDY OBJECTIVES Greenspace Enhancement with Stream and Riparian Woodland Restoration. Removal of Invasive Species. Section 404 Mitigation. Wildlife Habitat Corridor. Stormwater Management. Potential for NPDES Compliance. Project adjacent to completed 319 (h) funded City project.

31 CITY OF DECATUR GREENSPACE ENHANCEMENT CASE STUDY Baseline Studies Taken in 2008 and 2009 Soils Hydrology Geomorphology of Glen Creek Fish / Macro / Water Quality Riparian Vegetation Riparian Wildlife

32 CITY OF DECATUR GREENSPACE ENHANCEMENT CASE STUDY PERMITS and CONDITIONS Nationwide Permit 42/27 Phase 1 Cultural Resource Study Stream Buffer Variance Stormwater Quality Enhancement Mitigation / Restoration Plan 980-Ft. Stream/Riparian Restoration Monitoring and Success City of Decatur Stream Buffer Variance OTHER POTENTIAL BENEFITS ACHIEVED Fecal Coliform TMDL in SFPC Biota (Fish/Macro) TMDL in SFPC NPDES MS4 Stormwater/Restoration CIP MNGWPD Compliance Decatur Open Space Development Ord. Decatur Post-Dev. SW Management Ord. Decatur Floodplain Management Ord. Decatur Stream Buffer Protection Ord.

33 CITY OF DECATUR GREENSPACE ENHANCEMENT CASE STUDY Stream and Riparian Woodland Restoration

34 CITY OF DECATUR GREENSPACE ENHANCEMENT CASE STUDY Adjacenet to Glenlake Park (h) funded project

35 Questions?