RES 98-41 EELGRASS MONITORING AT CITY'S WATERFRONT PARKRESOLUTION 98-41
A RESOLUTION OF THE CITY OF BAINBRIDGE ISLAND,
WASHINGTON, APPROVING A MEMORANDUM OF
AGREEMENT BETWEEN THE CITY AND THE WASHINGTON
STATE DEPARTMENT OF TRANSPORTATION CONCERNING
THE PLANTING, MAINTENANCE, AND MONITORING OF
EELGRASS AT THE CITY'S WATERFRONT PARK.
WHEREAS, The Washington State Department of Transportation CWSDOT") has been
directed by the U.S. Environmental Protection Agency CEPA") to develop a plan that mitigates
for aquatic habitat loss resulting from cleanup of metals contamination at the north shore area of
the Eagle Harbor Superfund Site; and
WHEREAS, one component of the total mitigation plan is the proposed planting of 0.6
acres of eelgrass in the shallow subtidal area adjacent to the City' s Waterfront Park, and
WHEREAS, the City Council, on May 7, 1998, by Resolution 98-23, approved the
Waterfront Park Master Plan which includes provisions for expansion of the City' s public dock
facility;
WHEREAS, representatives of the City of the Bainbridge Island ("the City") have met
with representatives of WSDOT, EPA, Batelle Marine Sciences Laboratory and the City's
Harbor Management Advisory Committee to discuss the potential impacts to the City' s planned
expansion of the public dock resulting from planting of eelgrass in front of Waterfront Park:
now, therefore,
THE CITY COUNCIL OF THE CITY OF BAINBRIDGE ISLAND, WASHINGTON,
DOES RESOLVE AS FOLLOWS:
Section 1. The City Council finds that the 1992 Record of Decision issued by the EPA
and amended in 1995 which permitted on-site disposal and capping of contaminated soils at the
WSDOT ferry system maintenance facility was appropriate and necessary to contain and control
metals contamination in the vicinity of the noah shore of Eagle Harbor.
Section 2. The City Council finds that the WSDOT planting of 0.6 acres of eelgrass in
the shallow subtidal area adjacent to the City's Waterfront Park as proposed mitigation for loss
of aquatic habitat resulting from the cleanup remedy is appropriate and beneficial to the City.
Section 3. The City Council finds that, because of their structure and productivity,
eelgrass meadows are critical to the life history of aquatic resources in Eagle Harbor. Herring
spawn on the eelgrass leaves; Dungeness crab mate in the meadows and young crab utilize the
meadows for food and refuge; juvenile salmon feed extensively on small animals produced in the
meadows; and many clam species reach their greatest abundance in eelgrass.
Section 4. The City Council finds that, as proposed, the eelgrass planting will not
materially interfere with the City' s adopted plan to expand the public dock at Waterfront Park.
Section 5. The City Council approves and authorizes the Mayor to sign the following
Memorandum of Agreement with Washington State Department of Transportation:
a) The WSDOT agrees to plant, maintain, and monitor approximately 0.6 acres of
eelgrass as follows:
The eelgrass restoration site lies immediately west of the near shore fill in Eagle
Harbor on subtidal lands leased by the City from the Washington State Department of
Natural Resources, and covers approximately 0.6 acres (2,500 square meters). The new
site will provide optimal conditions for eelgrass growth within the vicinity of the near
shore fill..
Eelgrass will be planted into cap material as well as into native sediment at the
site. Planting will involve demarcating the site, collecting of plants from the donor sites,
holding plants in cooled containers, bundling plants for planting, planting plants at the
site, and quality assurance of the planting.
Monitoring will take place quarterly, with qualitative observations made in the
autumn, winter, spring and quantitative measurements made in the late summer.
b) WSDOT agrees to provide warning signs for two years to keep the public away from
the eelgrass planting area and prevent disturbance while the eelgrass is being
established.
c)
WSDOT agrees to provide and install interpretive signs on the City' s public dock and
the Waterfront Park shoreline. The signs will educate the public on the remediation
work and explain the beneficial effects of eelgrass.
d) The City agrees not to use the designated planting area for any other use.
PASSED by the City Council this 3rd day of September, 1998.
APPROVED by the Mayor this 3ra day of Septe~mber, 1998
D GHT SUTTON, May~r
A TTES T/AUTHENTI C ATE:
~KASPER, City Clerk
FILED WITH CITY CLERK:
PASSED BY THE CITY COUNCIL:
RESOLUTION NO.
HABITAT MITIGATION FOR WEST EAGLE HARBOR NEARSHORE FILL
EELGRASS (Zostera marina L.) MITIGATION PLAN SPECIFICATIONS
Ronald M. Thom and Liam D. Antrim
Battelle Marine Sciences Laboratory
6 April 1998
BACKGROUND
Washington State Department of Transportation (WDOT) has been working with the U.S.
Environmental Protection Agency (EPA) and others to complete habitat mitigation for nearshore
fill placed in West Eagle Harbor. The original habitat mitigation plan specifications (Thom
1997) were completed before the suitability of the proposed eelgrass transplant site had been
carefully assessed. In 1997-1998, site-specific studies were conducted at the proposed eelgrass
transplant site that included field planting experiments, water quality measurements, and
laboratory assays of sediment quality using eelgrass (Thom et al. 1998). The studies showed that
eelgrass will likely survive at the site, but modification of the site geometry and planting scheme
were needed to better maximize the probability of success and feasibility for conducting the
transplanting. In addition, data on eelgrass density was gathered by EPA Region 10
(unpublished data from Dr. Bruce Duncan) from two meadows within Eagle Harbor. These data
are useful in calibrating the performance criteria for the transplanted site. The present document
contains the specifications for eelgrass mitigation associated with the nearshore fill and includes
site description, goal, performance criteria, site survey, planting methods, monitoring, and
contingency plans. The mitigation addressed in these specifications involves transplanting
eelgrass onto a small delta adjacent to the location of the nearshore fill in Eagle Harbor,
Washington.
SITE DESCRIPTION
The transplant site is located within a gently-sloping, shallow subtidal area immediately west of
the nearshore fill area in Eagle Harbor (Figure 1). The transplant site is irregular in shape to
cOnfOrm to depths where eelgrass was proven to survive during site-specific studies. The site is
approximately 2500 m2 or 0.6 acres in area, between elevations of-2.0 ft and -5 ft MLLW. Dive
surveys of the plot found that the bottom sediments are comprised of silt and mud throughout,
except for the coarse sand and gravel used for the cap material.
GOAL
The goal of the present effort is to establish an eelgrass ecosystem at the site through natural
colonization facilitated by initial intensive eelgrass transplantation.
Habitat Mitigation for West Eagle Harbor Nearshore Fill Final - April 6, 1998 page 1
PERFORMANCE CRITERIA
This site was initially identified as an area of moderate probability of success of establishing an
eelgrass meadow through transplanting. Performance criteria established for the transplanted
meadow were based upon data from site-specific studies (Thom et al. 1998), reference eelgrass
meadows in and near Eagle Harbor (U.S. Environmental Protection Agency, Region 10,
unpublished), experimental studies identifying the maximum expected survival of transplant
units (approximately 80%; Battelle Marine Sciences Laboratory, Sequim, WA, unpublished), and
long-term monitoring of eelgrass transplants in the Pacific Northwest including Grays Harbor
(Thom 1995), Coos Bay (Donald Heinle, CH2M Hill, personal communication), Lincoln Park
(Antrim and Thom 1995), West Point (Allison Reak, Parametrix, personal communication, and
LaConner (Wyllie-Echeverria et al. 1994). The criteria of mean shoot density and percentage
eelgrass cover are formalized in the matrix in Figure 2. The matrix identifies three stages of
development of the ecosystem following transplantation: early (initial), intermediate, and late
(fully developed). The predicted time frame for reaching each of these stages is given also.
These performance criteria were modified from those in the original habitat mitigation plan
(Thom I997). The basic changes were: (1) initial mean shoot density will be between 1 and 5
shoots/m2 (instead of 0-10 shoots/m2), intermediate shoot density will predictability be 6-19
shoots/m2 (instead of 11-30 shoots/m2), and optimal shoot density will be >20 shoots/m2 (instead
of >30 shoots/m2); (2) plant cover is revised to the three categories of 0-5%, 6-50%, and >50%,
instead of 0-I0%, 11-70%, and 71-100%. These changes reflect the fact that, based on site-
specific studies, the site is predicted to have at maximum a bed of relatively low density and
cover under full development.
SITE SURVEY AND SITE-SPECIFIC STUDIES
For site-specific studies, a survey of the entire plot was made for the purpose of identifying areas
that may be inappropriate for transplanting, potential hazards to the transplanting effort, or
aspects of the site that may affect the eventual establishment of the meadow (Thom et al. 1998).
Trial transplants survived well in plots at -2 ft and -4.5 ft mean lower low water (MLLW) but not
at -1 ft MLLW. Growth and survival were greatest at the deeper sites. Turbidity, low salinity,
waterfowl grazing, or other disturbances may have been responsible for poor success at the
shallow depth. Therefore, the transplant plot was configured to maximize use of deeper areas
and avoid use of shallow areas. Recreational boat moorings are found at or near the deeper
boundary of the site and may damage eelgrass. Shading from a dock limits the area suitable for
planting on the west side of the site.
PLANTING METHODS
The preliminary site investigation revealed that the site contained very soft sediment with a
surface detritus layer that is very easily suspended by divers. The site quickly can become very
turbid, making planting evenly at specific spacing not feasible by divers. Therefore,
transplanting methods need to be appropriate for these difficult conditions.
Marking the Transplant Plot. The transplant site will be marked at its perimeter at 5- to 10-m
intervals with plastic stakes and cinder blocks. The exact location of the plot comers will be
mapped by measurement from and triangulation to fixed shore features. In addition, the position
Habitat Mitigation for West Eagle Harbor Nearshore Fill Final - April 6, 1998 page 2
of corners will be located to within 1 m using a global positioning system (GPS) with differential
correction so that they can be relocated in subsequent years.
Planting Units and Donor Stock. Planting units will consist of "bare root" bundles of 2-4
eelgrass shoots each. Bundles will be assembled using biodegradable ties and anchors. The
planting units will be handled extremely carefully and maintained moist or submerged in cool
ambient seawater as much as possible to avoid drying. Individuals experienced in this task
should prepare the units, and this should be directly overseen by an eelgrass expert who has
demonstrated and published documentation of successful eelgrass transplantation projects in the
Pacific Northwest.
A donor site acceptable to Washington Department of Natural Resources and EPA has been
identified. Eelgrass for transplanting in Eagle Harbor will be collected immediately adjacent to
and south of the ferry terminal in Clinton, Washington. Construction in 1998 and 1999 for
extension of the existing pier at Clinton will shade this donor site which has already served as the
donor site for eelgrass transplanting completed at Clinton in 1996 and 1997.
Planting, Spacing and Timing. A single bundle should be placed in shallow hole, and the hole
backfilled assuring that the rhizome and anchor are below the surface of the sediment. The
above ground (green) portion of the shoot should not be buried. These units will be planted using
a 2x2m frame plot (4 m2) for a guide in order to meet initial planting densities of 4 shoots/m2
over the entire site. Planting will be done in approximately 150 plots distributed over the site.
Plots will cover approximately 30% of the site. Planting will occur between April and
September 1998, with the majority of the effort completed by the end of May 1998.
MONITORING
Methods. Diver surveys conducted for preliminary site surveys found no eelgrass at the site.
Consequently, video transects were not completed to define baseline conditions. Diver-based
survey techniques also will be used for post-transplant monitoring. For qualitative assessments,
divers will relocate transplant plots, observe for survival and new growth in transplant bundles,
and make observations on physical or biological disturbances that may have affected the
eelgrass. Divers will record these notes, as well as take general photographs and video footage,
if water clarity allows, of the transplant plots and other important features noted relative to the
transplants (e.g., crab and sea star disturbances, macroalgae cover, boat and moorage
disturbances).
For quantitative assessments, average shoot density over the site will be measured by counting
all shoots within 50 randomly selected 4-m2 quadrats. In areas of high density, each 4-m2
quadrat may be subsampled with counts made on two 0.25- or 1.0-m~ quadrats. Percent cover
also will be estimated within quadrats as 0-5%, 6-50%, and >50%. If transplant bundles are
discernable, the number of individual shoots per bundle will be counted. Shoot length will be
measured in randomly selected plants from each quadrat. Observations on epiphyte growth, new
shoot growth, macroalgae cover, and potential disturbances will also be recorded.
Schedule. Monitoring of the transplant area will take place quarterly, with qualitative
observations made in autumn, winter, and spring following the initial transplanting. The initial
monitoring of the plot will be conducted 75-90 days following transplanting and will be used to
Habitat Mitigation for West Eagle Harbor Nearshore Fill Final - April 6, 1998 page 3
assess initial survival of the units. Quantitative measurements will be made in the summer
(June-August) 1999 and annually thereafter during summer for five years. The annual surveys
will be used to assess the long-term performance of the system as compared with the
performance criteria.
Reference and Donor Site Monitoring. Eelgrass density shall be recorded in either 1.0 or 0.25m2
quadrats at minimum of 30 random points within a reference meadow near the transplant site.
Reference site sampling shall be carried out within a week of monitoring at the transplant site.
Because it is anticipated that new construction scheduled for 1998-1999 at Clinton will shade
and eliminate eelgrass at the donor site, no monitoring of donor eelgrass beds will be required.
Reporting. The methods, results, conclusions and recommendations from the monitoring
program will be submitted in a brief report (i.e., <10 pages) to the project manager within 60
days of completing the field studies. The raw data and maps will be included in the report.
CONTINGENCY PLANS
The lack of any existing eelgrass at the transplant site coupled with variable eelgrass
transplanting success (e.g., Thom 1990) and trial transplants at the site suggest that there is
moderate uncertainty associated with the present transplant project. Under these types of
circumstances in aquatic restoration, the National Research Council (1992) has strongly
recommended an adaptive management approach to maximize the probability of success of the
project. The matrix in Figure 2 is intended to be used in an adaptive management program for
this project (Thom and Wellman 1997).
The predicted development through time of the system proceeds from the lower left box to the
upper right box (Figure 2). Annual assessments based on monitoring data will be used to
identify where the system is located in the matrix. The phrases in the matrix boxes are potential
reasons for the system being at that particular condition. If the system should deviate from either
the predicted time frame of development or the trajectory (i.e., other than diagonal from lower
left to upper right), potential reasons will be examined. Other information available from site
monitoring (e.g., sediment movement, storms, high macroalgae abundance, other disturbances)
will aid this analysis. It should be noted that if the first transplanting does not survive, there is
an agreement to replant at the site. If the second planting is not successful, then other
contingencies will be initiated.
Alternative solutions will be developed through evaluation of monitoring results and use of the
performance matrix. The most appropriate alternative solution will then be implemented.
Alternatives that will be examined include (a) no-action (if it is expected that more time is
needed for the system to develop as predicted), (b) supplemental transplanting to enhance the
rate of colonization, (c) modification of substrata types to enhance colonization, (d) source
control to reduce either sedimentation or inorganic nutrient supply to the site, and (e) abandoning
this site for another site more likely to result in successful mitigation through eelgrass
transplantation.
Habitat Mitigation for West Eagle Harbor Nearshore Fill Final - April 6, 1998 page 4
VARIANCES
Any variations from the specifications as described above must be approved by the WDOT
project manager prior to implementation.
SCHEDULE
The schedule of actions is shown in Table 1. The pre-planting survey has been completed and
documented in a report (Thom et al. 1998). Planting will occur between April and September
1998, with the majority of the effort completed by the end of May 1998. Monitoring will take
place quarterly, with qualitative observations made in autumn, winter, and spring, followed by
quantitative measurements made in summer 1999. Subsequent quantitative monitoring is
planned for summer months for a total five years after transplanting is completed.
REFERENCES
Antrim, L.D. and R.M. Thom. 1995. Lincoln Park Shoreline Erosion Control Project:
Monitoring for eelgrass, eelgrass transplant plots, Bull kelp, and surface substrate, 1995.
Prepared for U.S. Army Corps of Engineers, Seattle District. Pacific Northwest National
Laboratory, Battelle Marine Sciences Laboratory, Sequim, WA. PNL-10857.
National Research Council. 1992. Restoration of aquatic ecosystems. National Academic
Press, Washington, D.C.
Thom, R.M. and K.F. Wellman. 1997. Aquatic restoration monitoring: guidance for planning,
implementing and management of monitoring programs. Prepared for Institute for Water
Resources, U.S. Army Corps of Engineers. IWR-96-R-23. Pacific Northwest National
Laboratory, Richland, WA.
Thom, R.M., A.B. Borde, L.D. Antrim, W.W. Gardiner, A. Reak, and W.J. Taylor. 1998.
Eelgrass restoration at Eagle Harbor-Phase 1: Site and Sediment Evaluation for Eelgrass
Meadow Restoration. Prepared for Washington State Department of Transportation. Battelle
Marine Sciences Laboratory, Sequim, WA.
Thom, R.M. 1990. A review of eelgrass (Zostera marina L.) transplanting in the Pacific
Northwest. The Northwest Environmental Journal 6:121-137.
Thom, R.M. 1995. Year five eelgrass (Zostera marina L.) transplant monitoring in Grays
Harbor, Washington. Letter report to Seattle District, U.S. Army Corps of Engineers. Pacific
Noahwest National Laboratory, Richland, WA.
Thom, RM. 1997. Eelgrass (Zostera marina L.) mitigation plan specifications. Habitat
Mitigation for West Eagle Harbor Nearshore Fill. Unpublished report submitted to Hart
Crowser, Inc. Battelle Marine Sciences Laboratory, Sequim, WA
Habitat Mitigation for West Eagle Harbor Nearshore Fill Final - April 6, 1998 page 5
Wyllie-Echeverria, S., J.R. Cordell, J. Haddad and M.J. Hershman. 1994. Biological monitoring
of vegetation characteristics and epibenthic organisms from transplanted and reference eelgrass
patches at LaConner, Skagit County, Washington. 1990-1994. SMA 94-2, University of
Washington, Seattle.
Habitat Mitigation for West Eagle Harbor Nearshore Fill Final - April 6, 1998 page 6
N, .
0 60 120
Scale in feet
_,
City Park . a;s,~,,,ay, /
·
·
, . ,
: "· !';'" "'~"' ' "" ~ 'hfin Cap Boundry ~iii;i ii
· . . ,, ' ,
. .
·
." ' °" /'° .,
..
,
Area = 0,6 acre~s~- ~ - _ _ _ ..... - ./ '-,.~
Area = 26174 ~q. ft , '\
Area ' 2432 sq. m ~ ~ \
\
,
\
Figure 1. Site map showing the eelgrass transplant site in Eagle Harbor
Habitat Mitigation for West Eagle Harbor Nearshore Fill Final - April 6, 1998 page 7
*very large plants developed,
dlstrlbution not dumped
,potential disturbance indicated
jlarge plants developed,
distribution not dumped
*potential disturbance indicated
· early in development (1-12 mo.)
· high disturbancddlsruptlon ,
indicated
· smaller plants developed,
distribution not dumped
· potential disturbance Indicated
*Intermediate $ e of
development (1 months)
*moderate urbance/dlsruptlon
,density and cover fully developed
(36-60 months)
'stab!lty maximlzing
'serf-maintaining
,resilient to typical disturbances
'somewhat patchy development
*moderate disturbanceldlsruption
Indicated
· very patchy development, *extremely patchy, pockets of
pockets of dense eelgrass very dense eelgrass
· moderate disturbance/disruption *moderate disturbance/disruption
Indicated indicated
1 - 5 6 - 19 z20
AVERAGE SHOOT DENSITY
(no./sq. m)
Figure 2.
Matrix of performance and adaptive management of the meadow. The upper right
hand box indicates the final predicted performance of the meadow in terms of mean
density and percent cover. Phrases in the boxes indicate the state of the meadow and
the potential general reasons for this condition. These phrases are inteneded to guide
decisions on what to do if the meadow is not meeting the predicted performance
criteria.
Habitat Mitigation for West Eagle Harbor Nearshere Fill Final - Apdl 6, 1998 page 8
Table 1. Schedule for eelgrass mitigation in Eagle Harbor
ACTION
Pre-planting Survey
Mark Plots
Planting
Monitoring
Reporting
SCHEDULE
Completed January 1998
April-May 1998
April-September 1998
Initial quantitative in autumn, winter, and spring
following transplanting
Quantitative in summer (June-August), for five
years after planting is complete
Within 60 days after initial monitoring
Within 60 days after annual monitoring
Habitat Mitigation for West Eagle Harbor Nearshore Fill Final - April 6, 1998 page 9
~j
/ /
/ /
/ /
/ /
./ /
, /
/
/ /
/ /
/ / ·
/
oj
i