Transportation Land Development Environmental S e r v i c e s October 15, 2012 Dominion Resources C/O: EA Engineering, Science & Technology, Inc. 15 Loveton Circle, Sparks, MD 21152 Attn: Mr. William J. Rue Re: Survey for Sensitive Joint‐vetch [Aeschynomene virginica (L.) B.S.P.] Walkerton Property, King William County, Virginia VHB Project No.: 33625.00 Dear Mr. Rue: The attached document represents VHB’s final report on a sensitive joint‐vetch survey conducted in August 2012 on the above‐referenced property in King William County, Virginia. This work was completed pursuant to environmental studies and permitting for Dominion’s proposed North Anna Power Station Unit 3 project. If you have any questions regarding the information presented in this report, please feel free to call (757‐903‐7310) or email ([email protected]) at your convenience. Sincerely, VANASSE HANGEN BRUSTLIN, INC. By: Douglas A. DeBerry, Ph.D., PWS, PWD Senior Environmental Scientist 351 McLaws Circle Williamsburg, Virginia 23185-6316 757.220.0500 ▪ FAX 757.220.8544 email: [email protected] www.vhb.com Sensitive Joint‐vetch [Aeschynomene virginica (L.) B.S.P.] Survey Report Walkerton Property, King William County, Virginia VHB Project No.: 33625.00 Introduction At the request of EA Engineering, Vanasse Hangen Brustlin, Inc. (VHB) completed a survey for sensitive joint‐vetch [Aeschynomene virginica (L.) B.S.P.] on a small section of shoreline along the Mattaponi River in King William County, Virginia (see Figure 1). The area is known as Walkerton Landing, and the study site lies just east of the Route 629 bridge on the south flank of the river. This survey was conducted on behalf of Dominion Resources in support of environmental studies and permitting for their proposed North Anna Power Station Unit 3 project. The target species is a rare annual plant that grows in fresh to slightly brackish tidal marshes in the Mid‐ Atlantic region. The Walkerton Property contains approximately 500 feet of Mattaponi River shoreline along a portion of the river that is considered freshwater tidal (Silberhorn and Zacherle 1987). Therefore, this site is in an appropriate hydrogeomorphic setting to include potential habitat for sensitive joint‐vetch. The purpose of this investigation was to determine the presence of the federal‐ and state‐listed “threatened” sensitive joint‐vetch within the study area. VHB conducted fieldwork on August 27, 2012. No sensitive joint vetch plants were seen during the survey. Further, results showed that habitat conditions specific to the sensitive joint‐vetch (as described below) are not present on the property. Although freshwater tidal marsh habitat is present, the unique site conditions that are usually found where sensitive joint‐vetch occurs were not found within the study area. The following paragraphs provide a brief profile of the target species, a description of the site, the survey results, and concluding remarks. Species Description Diagnostic Characteristics and Habitat: Sensitive joint‐vetch is a tall annual plant in the Legume family (Fabaceae) bearing pinnately compound leaves and small, yellow flowers with light red venation (Gleason and Cronquist 1991, Weakley 2008). Although plant height is usually in the 0.5 meter to 1 meter range, it can grow up to 2 meters tall in some cases (Fernald 1950, Radford et al. 1968). The legume (pod) is produced in late summer to early autumn and breaks apart into 1‐seeded segments that are dispersed by floatation. The species is native to the Mid‐Atlantic states, and is known from a very restricted range in Virginia (Bailey et al. 2006). Suitable habitat includes slightly brackish to fresh, high diversity tidal marshes along rivers and creeks (Ware 1991, USFWS 1995). Upon dropping, sensitive joint‐vetch seeds either fall to the marsh surface at the location of the parent plant, or float until subtle high points or encumbrances in the marsh are encountered. Such “high” features are typically found along natural levees, bars, and wrack lines at the marsh fringe. The seeds are also likely to germinate in areas recently denuded of vegetation, such as muskrat “eat‐outs” and sediment depositional areas. Recent studies have suggested that sensitive joint‐vetch seeds have very low salinity tolerance, with Walkerton Property Sensitive Joint‐vetch Survey October 15, 2012 Page 2 germination rates decreasing significantly under increasing soil salinity conditions (Baskin et al. 1998, 2005). Methods All components of this study were completed by Douglas A. DeBerry, Ph.D., PWS, PWD of VHB, who is recognized as a sensitive joint‐vetch survey contact by the U. S. Fish and Wildlife Service. The late August site visit represents a time of year when the target species is in flower or fruit and is readily identifiable (Ware 1991, Belden and Van Alstine 2003). Prior to visiting the site, VHB reviewed aerial photography provided by EA Engineering, as well as other offsite reference materials such as topographic mapping, soil surveys, and National Wetland Inventory maps. Offsite review indicated potential for some small fringe marsh habitat toward the eastern side of the study area. During the site visit, all vegetated portions of the study area were accessed on foot. Notes were made regarding habitat conditions relevant to the sensitive joint‐vetch habitat criteria described above (see “Species Description”). In areas where marsh species were present, detailed searches were conducted on transects of approximately 10‐foot spacing to ensure overlapping visual ranges of adjacent transects. Representative photographs were taken to document field conditions during the study (see Attachments). [Note: Although wetlands are present west of the Route 629 bridge, no project impacts are expected to occur from the bridge westward. Therefore, this sensitive joint‐vetch survey focused on the east side of the bridge in the study area shown on the attached map]. Results Based on the results of this study, no sensitive joint‐vetch individuals were found on the Walkerton Property reviewed. In the context of the target habitat description provided above, the river shoreline in the western half of the study area is lacking in suitable marsh substrate for sensitive joint‐vetch colonization. Though some fringe wetlands are present on narrow benches at or above mean sea level, these areas are almost completely overreached by a moderate to closed canopy of shoreline‐inhabiting trees such as American sycamore (Platanus occidentalis), green ash (Fraxinus pennsylvanica), red maple (Acer rubrum), and hackberry (Celtis occidentalis). Understory species along the toe of shoreline include sneezeweed (Helenium autumnale), switchgrass (Panicum virgatum), Virginia wild rye (Elymus virginicus), and small white aster (Symphyotrichum lateriflorum var. lateriflorum). Some exotic and invasive species are also present along this section of the shoreline, including Japanese honeysuckle (Lonicera japonica), Japanese hop clover (Kummerowia striata), and Chinese privet (Ligustrum sinense). In general, the western section of the project area is lacking in suitable habitat for sensitive joint‐vetch due to shading from the prevailing tree canopy over most of the shoreline, as well as a lack of suitable marsh substrate throughout. In the eastern half of the study area, a freshwater tidal marsh occupies a small segment of the shoreline, extending out into the river approximately 50 feet. Locally dominant species in this habitat include smooth beggarticks (Bidens laevis), cardinal flower (Lobelia cardinalis), rice cut grass (Leersia oryzoides), Walter’s millet (Echinochloa walteri), halberdleaf tearthumb (Polygonum arifolium), arrowleaf tearthumb (P. sagittatum), arrow arum (Peltandra virginica), pickerelweed (Pontederia cordata), arrowhead (Sagittaria latifolia), swamp rosemallow (Hibiscus moscheutos), dotted smartweed (Polygonum punctatum), marsh dewflower (Murdannia keisak), strawcolored flatsedge (Cyperus Walkerton Property Sensitive Joint‐vetch Survey October 15, 2012 Page 3 strigosus), and tidemarsh amaranth (Amaranthus cannabinus). Though the emergent wetland fringe is a freshwater tidal marsh, the eastern half of the project area does not appear to contain suitable germination sites for sensitive joint‐vetch due to: 1) extended inundation times – the marsh does not appear to have any “high spots” or areas where sensitive joint‐vetch would be likely to colonize; 2) poor substrate conditions – portions of the substrate along the shoreline in this area are underlain by coarse gravel (see attached photographs); and, 3) high levels of vegetative competition from dominant species throughout. Conclusion Sensitive joint‐vetch was not observed on the Walkerton Property during this review. Although freshwater tidal wetlands are present on the property, a combination of factors likely render the project area unsuitable for sensitive joint‐vetch given the current scientific understanding of the habitat specificity in this species. Walkerton Property Sensitive Joint‐vetch Survey October 15, 2012 Page 4 References Cited: Bailey, D. E., J. E. Perry, and D. A. DeBerry. 2006. Aeschynomene virginica (Fabaceae) habitat in a tidal marsh, James City County, Virginia. Banisteria 27:3‐9. Baskin, J.M., R.W. Tyndall, M. Chaffins, & C.C. Baskin. 1998. Effect of salinity on germination and viability of nondormant seeds of the federal‐threatened species Aeschynomene virginica (Fabaceae). Journal of the Torrey Botanical Society 125:246‐248. Baskin, J.M., C.C., Baskin, & R.W. Tyndall. 2005.