Section 319
               NONPOINT SOORGE PROGRAM SOGGESS STORY
 Stakeholders Cooperate to Stabilize River and Restore Habitat
\A/3t6rbody ImprOVGd   Extensive sand and gravel extractions during a major
                                interstate highway construction project in the late 1970s led
 to channel instability and habitat problems in an eight-mile segment of New Hampshire's
 Pemigewasset River. As a result, the New Hampshire Department of Environmental
 Services (NHDES) classified this segment of the river as impaired by a non-pollutant in
 the 2004 Clean Water Act (CWA) section 305(b) report. In 2003 stakeholders launched a
 geomorphology-based project that restored the stream channel and improved habitat.
 Therefore, NHDES will not classify this river segment as impaired for aquatic life use by
 flow regime alterations in the state's 2012 CWA section 305(b) report.
 Problem
 The Pemigewasset River (Figure 1) originates in
 central New Hampshire's Franconia Notch State
 Park and flows south through the White Mountains
 until it merges with the Winnipesaukee River. In
 the late 1970s, sand and gravel were excavated
 from the river's active floodplain and used in
 constructing Interstate 93 near Woodstock, New
 Hampshire. The extraction created a 30-acre pit
 area and a large pond with depths up to 30 feet.
 The removal of floodplain materials  caused the
 river to jump its bank (a process known as an avul-
 sion) during a period of heavy rain when the river
 flow accessed the damaged floodplain. The river's
 new course flowed through unconsolidated materi-
 als and the pond.

 After the avulsion, this reach of the Pemigewasset
 River became excessively wide and shallow. It
 continued to have channel instability issues, includ-
 ing continuous bank erosion, channel widening,
 formation of multiple channels and degradation
 of the cold-water  fishery. The integrity and habitat
 of the pond were  also compromised as high river
 flows continued filling it with sediment. Surveys of
 channel dimensions at six cross sections indicated
 that the channel characteristics were such that the
 river could not effectively transport the watershed's
 flow and sediment volumes. Therefore, the reach
 was assessed as  non-supporting of aquatic life
 use due to streambank destabilization, and NHDES
 classified this segment of the Pemigewasset River
 as impaired by a non-pollutant (Category 4C) in the
 2004 CWA section 305(b) report.
Figure 1. A porous rock weir helps to stabilize the restored
section of the Pemigewasset River.
Project Highlights
In 2003 the Pemigewasset Chapter of Trout
Unlimited received a $14,038 CWA section 319
grant and began restoration planning. In 2006 the
Chapter received a second CWA section 319 grant
of $315,000 to finalize the construction  design,
obtain permits and complete the restoration on a
2,200-foot reach of the Pemigewasset River. The
geomorphology-based project reconnected the
river to its original channel, reduced the impacts
associated with floodplain land loss, enhanced
the in-stream and off-river fisheries and waterfowl
habitat, and restored the impacted river reach to a
stable condition.

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                    Project partners corrected
                    the channel's alignment,
                    elevations, and dimensions
                    by using large boulders to
                    construct more than a mile of
                    cross-vanes and rock vanes,
                    adding targeted streambank
                    toe protection, and creating
                    more than 900 linear feet
                    of floodplain stabilization
                    structures (Figure 2). Project
                    partners planted more than
                    150 mature willow clumps and
                    more than 50 trees ranging
                    from one to five inches in
                    diameter. They also planted
                    wetland grasses, plants and
bushes in the new riparian areas. Project partners
created in-stream habitat by shaping the chan-
nel and adding features such as pools, glides and
riffles. These features not only provided immediate
habitat benefits but also support diverse recre-
ational opportunities that had been absent from this
reach since the avulsion occurred. Anglers, boaters
and swimmers now enjoy Whitewater, swimming
holes and improved fishing opportunities along this
restored reach of river.
Figure 2. Construction
contractors and the project's
fluvial geomorphologist used
heavy equipment to construct
in-stream features.
Results
Members of Trout Unlimited, with technical assis-
tance from the project's consulting team, monitor
channel cross-section dimensions (cross-sectional
area, bankfull width, and bankfull depth) as the
prime indices of channel stability. To assess the
stability of the restored stream reach to determine
whether it supports the designated  use for aquatic
life, DBS reviewed geomorphic survey data collect-
ed in 2011. Analysis confirms that, despite signifi-
cant destruction of transplanted riparian vegetation
by beavers and record flood flows experienced
in the fall of 2011, the geomorphic indices in the
project area continue to remain within acceptable
ranges and are considered stable (Figure 3). The
stream reach now provides physical conditions
supportive of the aquatic life designated use. On
the basis of these data,  NHDES will  not classify the
river segment as impaired for aquatic life use by
flow regime alterations in the state's 2012 CWA sec-
tion 305(b) report. Pemigewasset River assessment
unit NHRIV700010203-01 remains on the CWA sec-
tion 303(d) list of impaired waters due to aluminum,
pH and mercury.
                                                                     Pemigewasset River Restoration Project-Supplemental Report
                                                                                 XS14-XSAreavs NH Reg. Hyd.Geom. Curves-provisional
                                                                                XSArea(sqft)
                                                                                LN [Predicted]
                                                                                67%UpperCI(+lSE)
                                                                                67% Lower CI(-ISE)
95%UpperCI(+2SE)

95%LowerCI(-2SE)
XS14
                                                                                      2.50   3.00   3.50   4.00   4.50
                                                                                       LN [Drainage Area (sq.mi.)]
                                                                 Figure 3. A regional hydrologic geometry curve shows how
                                                                 pre-project (2004) and post-project (2011) stream channel
                                                                 measurements for cross section 14 (black squares) compare to
                                                                 predicted stable channel condition dimensions (includes area
                                                                 between the upper and  lower confidence intervals). Data show
                                                                 that the restored  segment falls within the upper confidence
                                                                 interval, indicating that it maintains stable channel dimensions.
                                                                 Similar graphs were analyzed for multiple cross sections and
                                                                 stability indicator metrics.
                                                                 Partners and Funding
                                                                 Numerous partners cooperated on the project,
                                                                 including Trout Unlimited, New Hampshire Fish
                                                                 and Game Department, Horizons Engineering, the
                                                                 Chase family, NHDES and the U.S.  Environmental
                                                                 Protection Agency (EPA). EPA CWA section 319
                                                                 funds provided $14,038 for the initial study and
                                                                 $315,000 to administer, plan, document and imple-
                                                                 ment the restoration. Trout Unlimited provided proj-
                                                                 ect coordination in close cooperation with NHDES
                                                                 staff. Additional grant funding was provided by The
                                                                 New Hampshire Conservation Committee ($47,500)
                                                                 and the Davis Conservation Foundation ($10,000).
                                                                 The New Hampshire Fish and Game Department
                                                                 contributed $52,000, as well as additional techni-
                                                                 cal support, and an abutting landowner donated
                                                                 $260,000 worth of materials such as gravel, cobble,
                                                                 wetland grasses, bushes and trees.
UJ
O
     U.S. Environmental Protection Agency
     Office of Water
     Washington, DC

     EPA841-F-12-00100
     September 2012
                                                                 For additional information contact:
                                                                 Barbara McMillan
                                                                 Watershed Outreach Coordinator
                                                                 New Hampshire Department of Environmental Services
                                                                 603-271-7889 • Barbara.mcmillan@des.nh.gov

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