20160804 Ver 1 _Revised Mitigation Plan _20161114

Burdette, Jennifer a
From: Burdette, Jennifer a
Sent: Monday, November 14, 2016 3:44 PM
To: 'Hughes, Emily B SAW'
Cc: Higgins, Karen; Coburn, Chad
Subject: RE: Eagle Island Revised Mitigation Proposal
Emily,
As we discussed via telephone today, the Division believes that the revised mitigation proposal complies with
the mitigation requirement of the 401 water quality certification. Please provide a statement of availability
from the mitigation provider to restart the certification process.
Thanks,
Jennifer
Jennifer Burdette
401/Buffer Coordinator
Division of Water Resources - 401 & Buffer Permitting Branch Department of Environmental Quality
919 807 6364 office
[e-mail]
1617 Mail Service Center
Raleigh, NC 27699-1617
(Physical Address: 512 N. Salisbury St, Raleigh, NC 27604 - 9th Flr Archdale Bldg - Room 942F)
Email correspondence to and from this address is subject to the North Carolina Public Records Law and may be
disclosed to third parties.
-----Original Message -----
From: Hughes, Emily B SAW[mailto:Emily. [e-mail]]
Sent: Thursday, October 27, 2016 8:22 AM
To: Burdette, Jennifer a <[e-mail]>
Cc: Higgins, Karen <[e-mail]>; Coburn, Chad <[e-mail]>
Subject: Eagle Island Revised Mitigation Proposal
Jennifer,
Please see attached letter requesting approval for the revised mitigation proposal to offset impacts associated
with the Eagle Island toe berm construction. Deadline for your response is November 10, 2016. 1 will also be
soon providing you with an updated Pre -construction Notification Form to reflect these changes and the
additional information requested from the State on our Draft EA.

If you have any questions please let me know.
Thanks,
Emily

DEPARTMENT OF THE ARMY
t WILMINGTON DISTRICT, CORPS OF ENGINEERS
69 DARLINGTON AVENUE
WILMINGTON, NORTH CAROLINA 28403-1343
C
O tober 26, 2016
Planning and Environmental Branch
Ms. Jennifer Burdette
Division of Water Resources, 401 & Buffer Permitting Branch
Department of Environmental Quality
1617 Mail Service Center
Raleigh, NC 27699-1617
Dear Ms. Burdette:
This letter is in response to agency comments received on the Eagle Island Improvements Dike
Raise to 50 Feet (NAVD88) Draft Environmental Assessment (EA), pertaining to the mitigation
proposed for the required toe berm impacts. The overall consensus was that purchase of 3.04 acres of
coastal wetland credits from the Wilson Bay (Sturgeon City) Mitigation Site provided insufficient
mitigation and was out of the project's Hydrologic Unit Code (HUC). Project details were revisited
and the following revised proposal is being recommended.
Based on the discovery of a detailed vegetation analysis that was completed in 2015,
jurisdictional impacts have been decreased from 39 acres to 35.45 acres. The vegetation mapping
effort conducted in 2015 categorized the areas within the toe berm impacts into five classes:
"Native", "Majority Phrag", "Mix - Native/Phrag", "Tree/Shrub", and "Water" (Figure 1). As shown
on the attached map, the majority of impacts are Phragmites-dominated wetlands (34.79 ac). Areas
identified in green as tree/shrub were ground-truthed and determined to be uplands. Native, mixed
and open water impacts were combined to equal 0.66 ac., and together, jurisdictional impacts total
35.45 acres.
A site visit with the NC Division of Coastal Management on September 16, 2016 confirmed the
mapping. Open water areas were identified as being isolated and of little or no importance to
fisheries habitat. The Mean High Water Line (211 contour) was added to the map to identify impact
areas affected by daily tides during normal water levels (2.85 acres total).
Comments on the Draft EA from federal and state agencies regarding the quality of wetlands in
the impact area requested additional information to support the basis for considering Phragmites
ausiralis of "low" quality. Consequently, the North Carolina Wetland Assessment Method (NC
WAM) was conducted in two locations where toe berm impacts would occur: Site 1 on the north end
of Cell 3, and Site 2 on the southwest side of Cell 1, adjacent to the Brunswick River. A third
location adjacent to the Cape Fear River was identified, however, dense Phragmites prevented access
to natural ground, which is required to accurately apply the NC WAM. .
The NC WAM assesses wetlands by their identified wetland type and applies 22 metrics that rate
the quality of the site's Hydrology, Water Quality, and Habitat. Observations at Site 1 conclude that
the assessment area is saturated, however, it is not subject to tidal influence. Stands of Phragmites

-2 -
approximately 10-12 feet tall crowd out other native vegetation. Results from NC WAM based on
Hydrology, Water Quality, and Habitat were achieved and the overall rating for Site 1 is
"MEDIUM". Observations at Site 2 conclude that the area is saturated, however, it is undetermined
if infiequent flooding from tides occurs. Again, the Phragmites made it difficult to observe beyond 4-
5 feet within the assessment area, and lower areas closer to the river could not be accessed. Despite
the monoculture of Phragmiles, the overall result from NC WAM based on Hydrology, Water
Quality, and Habitat is "HIGH" (Hydrology and water Quality rate "HIGH", whereas Habitat rates
"LOW").
On the contrary, research on Phragmites australis revealed that Phragmites could have an impact
on hydrology as well, and negatively affect fisheries habitat. According to Ozbay (2014), "increased
levels of biomass result in an altered soil chemistry, a shift in the availability of primary production,
and elevated marsh surface, smoothed topography (i.e. the loss of rivulets), restricted flow to the
marsh interior, an increase in shade and litter cover, and lowered or altered pathways for nutrient
availability, especially nitrogen, for marsh nekton." Weinstein (1999) noted that Phragmites
"influences hydrology and hydroperiod through its effects on drainage density, and other geomorphic
features", "demonstrated generally greater tidal attenuation", and results in "reduction in biodiversity
of macrophytes with concomitant reduction in animal diversity." In.a 2000 study, Able and Hagan
found "that the larvae and small juveniles use the Spartina-dominated marsh surface frequently and
in large numbers, while they are seldom found in Phragmites-dominated marshes."
The Corps is proposing to mitigate for the 35.45 acres of toe berth impacts by purchasing credits
from the Lower Cape Fear Umbrella Mitigation Bank (Sneeden Tract). The Sneeden Tract is in the
project's HUC, located directly adjacent to the Cape Fear River, 5 miles upstream of Eagle Island
(Figure 2). This site has tidal freshwater marsh incorporated into its credits; as such, it is considered
in-kind to the toe berm wetland impacts on Eagle Island. For this reason and reasons stated above, we
are proposing to mitigate for impacts at a ratio of 1:1 (purchase of 35.5 mitigation credits) and
strongly believe this would result in a no net loss of wetlands.
We would appreciate your written response regarding our revised mitigation plan within two
weeks of the date on this Ietter (by November 10). If you have any questions or would like
additional information on the NC WAM assessments or the Sneeden Tract, please contact Emily
Hughes at [phone] or [e-mail].
Sincerely,
Elden Gatwood
Chief, Planning and Environmental Branch
Encls

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