19970616 Ver 1_Year 5 Monitoring Report_20071018

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RACEY MITIGATION SITE ON LAXON CREEK,
WATAUGA COUNTY
Year 5 Monitoring Report
Period Covered: July 31, 2005 - June 27, 2006
Prepared for the
North Carolina Ecosystem Enhancement Program
North Carolina Wildlife Resources Commission
Division of Inland Fisheries
Watershed Enhancement Group
Raleigh
2007
This report summarizes the 2006 monitoring data collected from 1,160 linear feet of stream
channel on Laxon Creek at the Racey stream mitigation site in Watauga County (Figure 1), and
compares it with four previous years of monitoring data. Mickey and Scott (2001) described pre-
construction survey methods, site conditions, and project objectives. The purpose of the project
was to improve aquatic habitat, reestablish riparian area vegetation, and establish stream channel
stability. This monitoring report is submitted as partial fulfillment of the off-site stream
mitigation requirements of the North Carolina Department of Transportation (NCDOT) for the
R-0529 US 421 road improvement project in Watauga County. For that project, a total of 14,814
linear feet of stream mitigation were required by the United States Army Corps of Engineers
(USACE) Section 404 permit and 7,407 linear feet of mitigation were required by the North
Carolina Division of Water Quality (NCDWQ) Section 401 water quality certification.
From 2000 to 2005 all reports associated with this mitigation site were prepared for the
NCDOT stream mitigation program. In 2005, responsibility for this site was transferred from
NCDOT to the North Carolina Ecosystem Enhancement Program (EEP). This document was
prepared using guidelines developed by the North Carolina Wildlife Resources Commission.
This was done to maintain consistency with earlier reports and to facilitate the comparison of the
2006 data with previous years' data.
Monitoring
The 2006 monitoring survey data were collected on May 17 and 18. These data are
compared with as-built data and the previous years monitoring data (Mickey and Scott 2001;
Mickey and Hining 2003; Mickey and Wasseen 2006). The 2006 monitoring survey included a
longitudinal profile, channel cross-section dimension measurements, pebble counts, and woody
plant stem counts (planted trees/live stakes). A photographic chronology of the site was
maintained at three locations: stations 1+88, 7+33, and 8+40 (Appendices 1-3). Photographs are
taken looking upstream.
Bankfull Events
Bankfull flow events were documented through review of the United States Geological
Survey's South Fork New River flow gage (gage number 03161000) near Jefferson, North
Carolina, by photographs and by personal observations of bankfull stage pins placed on site.
Bankfull at the Racey site corresponded to approximately 1,800 cubic feet per second at the gage
station. However, due to the localization of many rain events, some bankfull events could only
be confirmed by direct observation (visiting the site after a rain event or through contact with the
landowner). Since completion of the project there have been 14 bankfull or greater events at the
site (Table 1).
Longitudinal Profile
Prior longitudinal profile survey data indicated little change in the channel thalweg (Figure
2). Visual observations prior to the 2006 longitudinal profile survey revealed the channel had
changed little from previous surveys; therefore a decision was made to collect longitudinal
profile data only from station 0+0 to 4+00; approximately one-third the project length (Figure 2).
The remaining portion of the channel was to be surveyed if the data showed a significant change
in the channel thalweg. There was no appreciable change in the profile of this section between
2001 (as-built) and 2002; however, in 2003 beavers constructed dams at stations 1+58, 3+58,
6+53, and 8+58. These dams were subsequently washed out during the flood events associated
with a series of hurricanes in 2004. The 2006 data reveals minor changes in stream bed elevation
at stations 0+48 to 1+58 and 2+64 to 3+40 that can be attributed to sediment being deposited
behind the beaver dams. It should be noted that the 2001 and 2002 longitudinal profile surveys
ended at station 9+23 because little construction activity occurred between this point and the
confluence of the South Fork New River. Comparison of the 2006 data with previous years
indicates that the minor changes in the longitudinal profile are the result of normal storm events
and not the result of stream enhancement activities.
Cross-sections
Four cross-sections were surveyed in 2006 and compared with previous cross-section
measurements (Figure 3; Mickey and Scott 2001; Mickey and Hining 2003; Mickey and
Wasseen 2006). Cross-sectional dimensions showed some adjustment following the 2004
hurricanes when compared with the previous years monitoring survey data (Figure 3). This
included minor adjustments in thalweg depths and minor lateral movement of the channel. Most
of the cross-sections exhibited minor build up of the streambanks due to deposition of soil
materials (silt, sand, small gravel) during high flow storm events.
CROSS-SECTION 1+88 - run (Figure 3.1): This cross-section is located just above a root
wad. There has been little change in the cross-section from 2001 through 2006. The thalweg
deepened and the channel widened slightly following the three September 2004 hurricanes; in
spite of this the banks are stable and well vegetated.
CROSS-SECTION 2+08 - pool (Figure 3.2): This cross-section is located over the middle
of a pool just below a rock weir and has changed little over time. The thalweg has remained
stable compared with the 2005 data, but has deepened when compared to the as-built through
2004 measurements. Although the channel widened slightly following the three September 2004
hurricanes, the banks are stable and well vegetated.
CROSS-SECTION 7+13 - step pool (Figure3.3): This cross-section is located between two
rock weirs. The thalweg has deepened since the 2001 as-built survey was completed. The
streambanks are stable and well vegetated. While the banks are stable, the steep right bank
should be monitored for potential bank erosion problems. Overall this cross-section is stable.
CROSS-SECTION 8+40 - run (Figure 3.4): The thalweg has deepened since the as-built
survey was completed. Both streambanks are aggrading as the vegetation continues to grow and
trap sediment (silt, sand, and small gravel). The stream channel at this cross-section has
remained stable throughout the five years of monitoring.
Immediately below cross-section 8+40 the left bank has migrated slightly and a central bar
has developed creating a separate channel along the right bank. These channel adjustments are
the direct result of beaver activity during 2003-2004. While both banks are well vegetated and
stable, there is the potential risk of bank erosion developing along the right bank should the
central bar continue to grow. This location should be monitored for bank erosion problems.
Substrate
Pebble count data were collected from a riffle at cross-section 1+88 (Figure 4). Pavement
analysis trends remained consistent from 2003 to 2005. In 2006 there was a slight downward
trend for all particle sizes except for the D84. Since 2001 the D50 cumulative distribution has
ranged in size from medium gravel (9.5 mm) to very course gravel (39.0 mm) to course gravel
(23.0 mm) (Figure 4). Fluctuations in particle size are normal and can be attributed to sampling
bias, flood events, and sediment being transported from disturbed land higher in the watershed.
These changes are not significant enough to show any trends or negative impacts.
Riparian Improvements
Since construction was completed on November 3, 2000, all disturbed banks have become
well vegetated (Appendices 1-3). A total of 412 stems comprised of live stakes and bare-rooted
plants were planted within 0.67 acres of disturbed streambanks in 2001 and 2002 (Table 2). A
total of 179 stems were counted in 2006 (43% survival) (Table 2). The density of stems in the
disturbed areas planted is 267/acre (179 stems/0.67 acres), which is above the 260 stems/acre
required for woody species planted at mitigation sites through year five of monitoring (USACE
2003). It should be noted that the stem counts and survival calculations did not include seven
black cherry Prunus serotina, 14 white pine Pinus strobes, and 18 black walnut Juglans nigra
planted by the landowner in 2001.
Site Repairs
A major flood event occurring on November 19, 2003 resulted in some minor damage to the
rock crossvane at station 3+57 (Appendix 4). Damage to the structure occurred after a ford
crossing was replaced with a bridge by the landowner in 2002 (construction of a bridge at this
location was permitted in the conservation easement). Flood waters crested the bridge and
lateral movement of flood waters was constricted by the bridge abutments. This constriction
resulted in the flood waters creating an upward current under the crossvane boulders, causing the
structure to fail. Under normal flood conditions water would have flowed over the structure,
holding it in place. This structure, along with some minor bank damage immediately
downstream from the site, was repaired on February 25, 2004. These repairs have been the only
ones required at this site since construction was completed on November 3, 2000 (Mickey and
Scott 2001).
Summary
It has been almost six years since construction at the Racey site was completed. During this
period there have been 14 bankfull or greater events resulting in only minor damage at the site.
The streambank improvements and repairs have remained stable with no failures noted. In-
4
stream structures are functioning as designed. The riparian vegetation is thriving and continues
to build and stabilize the streambanks.
Recommendations
The steep right bank at cross-section 7+13 and the central bar below cross-section 8+40
should be monitored annually for bank erosion problems. The interpretation of the five years of
monitoring data, the fact that there have been no major failures to the structures or streambanks,
and the continuing growth of the dense riparian vegetation suggests that the stream reach at the
Racey site is stable, and needs no further detailed monitoring. It is our recommendation that this
site be considered stabilized and released from further monitoring. Furthermore, we recommend
NCDOT be awarded 1,160 mitigation credits (1:1 ratio) for this site as approved by NCDWQ
(NCDWQ letter to the NCWRC dated November 6, 2000).
Acknowledgements
J. Mickey, Jr., J. Wasseen, II and S. Hining of the Elkin watershed enhancement team
collected and analyzed the field data; J. Wasseen, II and J. Mickey, Jr. prepared this report. J.
Borawa improved the report with his thorough review and thoughtful suggestions.
References
Mickey, J. H. and S. Scott. 2001. As-built report for the Racey mitigation site, Laxon Creek,
Watauga County. North Carolina Wildlife Resources Commission, Raleigh.
Mickey, J. H. and S. Hining. 2003. Carp mitigation site, unnamed tributary to Laxon Creek,
Watauga County. Period covered: April 2, 2002 - April 15, 2003. North Carolina
Wildlife Resources Commission, Raleigh.
Mickey, J. H. and J. Wasseen, II. 2006. Carp mitigation site, unnamed tributary to Laxon Creek,
Watauga County. Period covered: June 3, 2004 - September 27, 2005. North Carolina
Wildlife Resources Commission, Raleigh.
USACE (U.S. Army Corps of Engineers), Wilmington District, U. S. Environmental Protection
Agency, North Carolina Wildlife Resources Commission, and the North Carolina
Division of Water Quality. 2003. Stream Mitigation guidelines. Wilmington, North
Carolina.
F[GUPE 1.-Location of Racey mitigation site, Laxon Creek, Watauga County.
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FIGURE 3.-Four cross-sectional dimension comparisons, Racey mitigation site, Laxon
Creek, Watauga County 2001-2006.
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Z. 100 ..,. _ _.?
98
w 96
94
0 10 20 30 40 50 60 70
Width (ft)
-2001 As-Built -?- 2002 Monitoring - 2003 Monitoring - 2004 Monitoring
2005 Monitoring 2006 Monitoring
FIGURE 3.1.-Cross-section 1+88, run.

FIGURE 3.-Continued.
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100
0 98
96
w 94
92
0 10 20 30 40 50 60 70
Width (ft)
2001 As-Buih -+- 2002 Monitoring - 2003 Monitoring -¦- 2004 Monitoring
2005 Monitoring 2006 Monitoring
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FIGURE 3.2.-Cross-section 2+08, pool.
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FIGURE 3.-Continued.
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0 94
> 92
w 90
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0 10 20 30 40 50 60 70
Width (ft)
t 2001 As-Built -+- 2002 Monitoring -•- 2003 Monitoring - 2004 Monitoring
2005 Monitoring - 2006 Monitoring
FIGURE 3.3.-Cross-section 7+13, step pool.
FIGURE 3.-Continued.
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0 10 20 30 40 50 60
Width (ft)
-+- 2001 As-Built -+- 2002 Monitoring - 2003Monitoring
- 2004 Monitoring 2005 Monitoring -- 2006 Monitoring
FIGURE 3.4.-Cross-section 8+40, run.
10
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FIGURE 4.-Pebble count data comparisons, Racey mitigation site, Laxon Creek, Watauga
County, 2001-2006.
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Silt/Clay Sand Gravel Cobble Boulder
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2005 Monitoring cumulative % - 2006 Monitoring cumulative %
Size class Parti cle size (m m) in year s ampled
index 2001 2002 2003 2004 2005 2006
D16 1.2 0.4 4.3 3.6 8.2 2.1
D35 6.4 12.0 16.0 19.0 24.0 13.0
D50 9.5 19.0 39.0 38.0 39.0 23.0
D84 91.0 190.0 110.0 84.0 80.0 81.0
Dg5 200.0 390.0 160.0 120.0 140.0 130.0
12
TABLE 1.-Monitoring of inner berm and bankfull events at Racey mitigation site based on
data from the United States Geological Survey South Fork New River gage (gage number
03161000) near Jefferson, Ashe County, North Carolina and from on-site observations.
Date Gage height (ft) Flows (cfs) Comments
2/22-23/03 5.0 2,250 Bankfull event (gage quit working)
3/16/03 4.4 1,725 Inner berm event
4/10/03 5.4 2,819 Bankfull event
4/18/03 5.6 3,200 Bankfull event
6/7/03 4.1 1,820 Inner berm event
6/17/03 4.7 2,000 Bankfull event
8/9/03 4.2 1,450 Inner berm event
8/10/03 4.1 1,400 Inner berm event
11/19/03a 5.4 1,880 Bankfull event
2/7/04 4.8 2,080 Bankfull event
9/2/04 11.7 14,700 Bankfull event (hurricane)
9/13/04 8.6 7,550 Bankfull event (hurricane)
9/28/04 6.3 3,820 Bankfull event (hurricane)
7/8/05 4.6 2,000 Bankfull event (tropical storm)
10/7/05 4.0 1,410 Inner berm event (tropical storm)
11/29/05 6.5 4,130 Bankfull event
1/18/06 5.2 2,460 Bankfull event
2/5/06 4.4 1,690 Inner berm event
4/22/06 4.3 1,610 Inner berm event
6/25/06 6.8 4,470 Bankfull event (tropical storm)
6/27/06 5.7 3,130 Bankfull event (tropical storm)
Chis event produced rainfall in excess of six inches at the Racey site that resulted in major,
localized flooding (see Appendix 4).
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Appendix 1: Photographic log of the Racey mitigation site looking upstream at cross-
section 1+88, Laxon Creek, Watauga County, October 2000-July 2005.
May 29, 2001.
November 3, 2000 after construction.
October 30, 2000 before construction.
August 14, 2003.
July 9, 2002.
June 30, 2004.
15
APPENDIX 1: Continued.
July 21, 2005.
April 24, 2006
16
APPENDIX 2: Photographic log of the Racey mitigation site looking upstream at cross-
section 7+13, Watauga County, October 2000-July 2005.
October 30, 2000 before construction.
November 3, 2000 after construction.
June 1, 2001.
July 9, 2002.
May 14, 2003.
June 7, 2004.
17
APPENDIX 2: Continued.
July 21, 2005.
April 24, 2006.
18
APPENDIX 3: Photographic log of the Racey mitigation site looking upstream at cross-section
8+40, Watauga County, October 2000-July 2005.
November 2, 2000 after construction.
October 30, 2000 before construction.
May 29, 2001.
July 30, 2002.
July 14, 2003.
June 7, 2004.
19
APPENDIX 3: Continued.
July 21, 2005.
May 18, 2006.
20
APPENDIX 4. Overview photograph showing the location of the bridge at longitudinal
profile station 3+57 during the November 19, 2003 flood event on Laxon Creek, Watauga
County. The rock crossvane at this location was damaged during the flood and had to be
repaired. Photograph courtesy of Dr. Jana Carp.
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