Maryland Department of Natural Resources - Dyke Marsh Alternatives
18 June 2012
To: Brent Steury, National Park Service
From: Greg Golden, Director, Environmental Review Unit, Maryland Department of Natural Resources
Subject: Dyke Marsh Wetland Restoration and Long Term Management Plan/ Environmental Impact Statement, Alternative Concept Newsletter, Potomac River, Virginia
The Department of Natural Resources (the Department) received through concerned citizens an internet link at: http://parkplanning.nps.gov/document.cfm? parkID=186&projectID=20293&documentID=47011 (accessed 18
May 2012) regarding the Dyke Marsh Wetlands Restoration and Long Term Management Plan / Environmental Impact Statement (EIS) Alternative Concept Newsletter (the Plan) prepared by the National Park Service (NPS). This plan presented four restoration Concepts for the Dyke Marsh Wildlife Preserve (Dyke Marsh), a tidal wetlands marsh located in Virginia waters of the Potomac River that has significantly eroded. While the project site is in Virginia waters, the site is in close proximity to Maryland waters. Due to the migratory and interstate nature of aquatic resource populations in this area and also the interstate characteristics of recreational user groups on the Potomac River, the Department has strong interests in this project and would like to continue direct interagency coordination with Federal, State, and local agencies, to help optimize the project’s regional, ecosystem-based aspects of protection and restoration of natural resource elements.
Based on the importance of aquatic habitat elements and features discussed further below, the Department prefers Concept B, which avoids the placement of fill material in the localized deep water habitat areas located outside of
the main river channel and in close proximity to marsh and shallow water areas. We acknowledge that carefully considered and selected areas of additional fill may be required to establish and stabilize tidal guts, pools and low marsh within the created marsh area, as detailed planning is conducted. The distinctiveness and value of the localized deep water habitat in this area are significant, as are the natural interface features between marsh, shallow water, and deep water areas. Concept B, with expected additional design details and adjustments, appears to offer by far the best opportunity to balance these aquatic resource elements.
The EIS evaluates four Concept alternatives. It is our understanding that due to Congressional mandate, Concept A – “No Action”, is an unlikely feasible option for this site, as the existing marsh is eroding and degrading and no restoration elements are involved in Concept A. Concept A serves as a point of comparison for the other options.
Concept B appears to balance marsh creation with shallow and deep water habitat. Concept C includes extensive shallow water conversion to marsh and the placement of fill in deep water habitat. Concept D, in addition to the placement of extensive fill in open water habitat, directly transforms open water areas a djacent to Belle Haven Marina. The exact effect and potential impact of Concept D on the Marina and its users cannot be fully determined
from the Plan at this time, but we have concern for potential impact to Marina utility and function for public access, as we are aware that many (interstate) recreational users of the River access at this location. Recreational 2 access to the Potomac River in this area (to include nearby Maryland and District of Columbia) is somewhat limited and constrained, in relation to its high recreational value.
The Department fully supports restoring lost wetlands within Dyke Marsh and acknowledges the need to minimize erosion and stabilize and replenish the marsh to restore and enhance Dyke Marsh’s natural ecological processes.
Present erosion rates within Dyke Marsh are significant and need to be rectified. The historical mining of sand and gravel at Dyke Marsh had a negative impact on the wetlands, but also resulted in several deep water channels (4.6 – 7.6 m at high tide) that are highly beneficial to fishes. It is a reasonable probability that prior to colonization by Europeans and subsequent wetland, floodplain, and waterway filling; shoreline hardening; and increases in erosion
and sedimentation, shallow and deep water habitat complexes outside the main channel would have been abundant throughout the tidal Potomac River. This is no longer the case for extensive reaches of the River and its tributaries within the Washington Metropolitan area. Dyke Marsh’s deep water habitat provides a unique spawning environment for nest building fishes (largemouth bass) and possibly anadromous fishes, and prime nursery areas for anadromous fishes, while the adjacent vegetated area outside the main channel offer large predators optimal feeding habitat and overwintering refugia for fishes1. Dyke Marsh encompasses a productive, tidal marsh and open water complex that offers extensive recreational opportunities for boating, fishing, sightseeing and birding.
The deep water channels within Dyke Marsh may also be important migratory corridors for some species, such as Atlantic and shortnose sturgeon. The deep-water habitat within Dyke Marsh offers fish and other biota a refuge from high river flows. We would recommend a spatial analysis of deep-water habitat adjacent to the main channel
be performed to further assess the regional importance of the habitat elements in Dyke Marsh within the tidal Potomac River area.
The Potomac River supports numerous fish species that prefer structure for feeding, refugia and/or spawning. One aspect that we could not find addressed in the Plan information to date is an evaluation of the aquatic resources within Dyke Marsh. U.S. Fish and Wildlife Service (USFWS) fisheries data collected by from 2001-2004 within Dyke Marsh focused on rare, threatened or endangered (RTE) fish species such as Atlantic and shortnose sturgeon
and they concluded that their surveys did not collect RTE fish species during those years. We recommend that the Federal agencies continuing work on these two species (National Marine Fisheries Service and USFWS) be asked for written comments for the project study, updated to 2012, and made available for other review agencies to consider. Specifically, it would be important to know whether more recent survey results exist, and also to what degree potential habitat for these species factors into Federal review at this site. In other parts of the Bay and its tributaries, potential habitat has played a significant role in project review for large projects. In addition, the Department recommends pre- and post-restoration fishery surveys for the broad range of aquatic species which may be present seasonally or year round, to ensure that restoration of Dyke Marsh has not negatively impacted either the abundance or condition of aquatic species.
The Belle Haven Marina is located on NPS property and offers boaters access to the mainstem river at a convenient location and access to this marina should remain open to the public. Available public boat ramps are limited in the tidal fresh areas of the Potomac River near Dyke Marsh. The launch at Belle Haven undoubtedly serves as an important access point for Maryland, Virginia, and D.C. residents. This launch site also offers kayakers and canoeist a protected area to launch during most weather conditions. Potential future elimination of
the Belle Haven Ramp, or significant change in the character of nearby navigable waters, will reduce or impact access to the mainstem Potomac River for anglers and may increase congestion at other boat ramps. Recreational boaters and anglers have also contacted the Department concerning boating regulations within Dyke Marsh. We 1 (http://www.gameandfishmag.com/2011/07/01/tactics-for-rigging-and-catching-moving-water-catfish/ and http://www.washingtontimes.com/news/2012/may/2/gene-muellers-fishing-report-635374152/?page=all). 3 are concerned about the lack of information on the website concerning the No Wake Zone, limited boating parties, personal watercraft exclusion, and seasonal, gas motor restrictions (noise reduction) rules due to RTE marsh species within the NPS boundary. Although we fully support protecting RTE species, NPS rules and regulations should be clearly posted at multiple locations including the NPS website and the park boundary, particularly on the waterside of Dyke Marsh for boaters not using the Belle Haven Ramp. This would aid the Department’s need too better serve its stakeholders operating in these interstate areas of the Potomac River.
After careful evaluation and review, the Department’s preference for Concept B acknowledges that additional fill may be required to optimize in a balanced manner the wetland values and stability of the area, as well as to establish tidal guts. However, the placement of fill in the deep water areas within Dyke Marsh should be avoided to maintain an important habitat feature and minimize potential fisheries impacts. We strongly recommend interagency discussions led by the NPS to analyze and comment on quantifiable estimates of impacts by Concept, including the full scope of living and natural resources, and we advocate reaching interagency concurrence on the final proposed extent of the fill.
The consideration of Concept B with additional adjustments to the wetland creation aspects during continued planning, but designed to still result in far less open water fill than Concept C, could be considered as a “hybrid” approach. This approach would replenish and stabilize the shoreline, thereby preventing wetland loss, and would
include construction of the promontory structure. This hybrid option should prevent wetland loss due to winds and storms and supports wetland creation, resulting in increased available habitat for marsh birds, vegetation, and insects while minimizing habitat loss to aquatic life and maintains boat access via Belle Haven Marina. Potential post restoration benefits for Dyke Marsh also include increased primary production, nutrient cycling and improved water quality. In general, Dyke Marsh restoration should include the following:
1. Continued public access,
2. Incorporation of numerous tidal guts including pools and deeper marsh channels to maximize the water/marsh interspersion to provide microhabitat to intertidal species and wildlife species,
3. Maintenance or improvement of hydrology and water quality,
4. Preservation of shoreline habitat and if hardened shoreline structures are used, these should be limited and non-contiguous,
5. Incorporation of native, vegetative plantings,
6. Incorporation natural material when feasible which are aesthetically appealing, and
7. Long-term post-restoration monitoring.
We recommend a quantitative analysis of the submerged aquatic vegetation (SAV) distribution in the project area and quantification of any unavoidable SAV impacts. The NPS should also provide options to mitigate any unavoidable impacts to SAV. If interagency coordination determines that there are remaining gaps in information regarding potential for additional rare, threatened or endangered species on site, especially aquatic species, we
would recommend consideration of additional study, as coordinated with the lead agencies for the protection of those species (State or Federal). Lastly, we would recommend a thorough investigation of the pipeline area referenced in the Plan materials to ensure any structural modifications proposed for Dyke Marsh will not impact this structure.
We also acknowledge and concur with the research by the University of Maryland, Center for Environmental Science (UMCES) into the causes for sediment deposition and erosion and vegetation alterations and its possible impact to resources2. We also are concerned with the effects of sea level rise on the Dyke Marsh community, also stated the UMCES research. We also fully support the future research by UMES to model the impacts of http://www.umces.edu/al/project/dyke-marsh-restoration
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restoration on the biota in the marsh and their suggestion to increase the elevation of the marsh due to sea-level rise.
In closing, the Department recommends that potential impacts be evaluated using both an environmental assessment approach (quantifying gain or loss of habitats) and an economics approach (assessment of recreation and eco-tourism gains or losses); both approaches result in prediction and quantification of impacts and these should be clearly presented to the public and the agencies. Dyke Marsh is a unique resource because of its proximity to Washington, DC, public access to the Potomac River afforded by the boat ramp and the interstateoriented
ecological and recreational value resulting from the diversity of upland, marsh and riverine habitats.
Thank you for the opportunity to comment on the referenced document. As a summary, after careful evaluation and review of the background research and data within Dyke Marsh, the Department prefers Concept B but acknowledges that additional fill may be required to establish tidal guts; fill locations should not include deep water areas within Dyke Marsh because of its potential habitat distinctiveness, and the potential resulting fisheries
impacts. We would also recommend interagency discussions led by the NPS resulting in inclusive and comprehensive analysis with quantifiable estimates of impacts by Concept and interagency agreement to determine the extent of the fill. If you have any questions concerning these comments or need a contact person for the Department, please contact Bob Sadzinski of my staff at 410-260-8312, or bsadzinski@dnr.state.md.us.