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Home , Freshwater marsh, Mudflat, Tidal marsh, Wetland

Darby Creek Mouth Delaware County, PA Ü Natural Heritage Inventory

Legend Core (focus NHI site) Core Habitat (other NHI sites) Interior Forest Supporting Forested habitat 100 meter Riparian Buffer OpenSpace & Recreation 0 0.25 0.5 1 100 foot Riparian buffer Public Park Kilometers Township Boundary Homeowner's Association 0 0.25 0.5 1 Miles County Boundary Privately Eased Land

Darby Creek Mouth Mudflat – Exceptional significance

PNDI Rank2 Legal Status2 Last Species of Concern: Taxa1 Global State State (Proposed) Seen Quality2 Waterhemp ragweed (Amaranthus cannabinus) P G5 S3 PR (PR) 2009 C Eastern baccharis () P G5 S3 PR (PR) 2007 D beggar-ticks (Bidens bidentoides) P G3G4 S1 PT (PE) 2009 D Beggar-ticks (Bidens laevis) P G5 S1 N (PE) 2009 BC Wrights spike rush (Eleocharis obtusa var. peasei) P G5 S1 PE (PE) 1994 B Little-spike spike-rush (Eleocharis parvula) P G5 S1 PE (PE) 1994 B Multiflowered -plantain (Heteranthera multiflora) P G4 S1 PE (PE) 1994 B Bugleweed (Lycopus rubellus) P G5 S1 PE (PE) 2009 D Shrubby camphor-weed (Pluchea odorata) P G5 S1 TU (PE) 2009 E Long-lobed arrow-head (Sagittaria calycina var. spongiosa) P G5 S1 PE (PE) 2009 AB Subulate arrowhead (Sagittaria subulata) P G4 S3 PR (PR) 2001 BC bulrush (Schoenoplectus fluviatilis) P G5 S3 PR (PR) 2001 A Indian wild rice (Zizania aquatica) P G5 S3 PR (PR) 2009 D Sensitive species of concern3 ------2000 E

1 A = ; B = ; C = Community; F = ; L = Lepidopteran; O = Odonate; P = ; M = ; R= , U = Unionoid (Mussel) 2 Please refer to Appendix III for an explanation of PNHP ranks and legal status 3 This species is not named by request of the jurisdictional agency overseeing its protection

Location: The tidally influenced area at the confluence of Darby Creek and the Delaware River south of Interstate 95. o Municipalities: o Ridley Township o Tinicum Township o USGS Quadrangles: o Bridgeport Quadrangle o Watersheds: o Darby Creek o Delaware River o 1992 Delaware County Natural Areas Inventory reference: o “SP587”, “SP534” (Bridgeport Quadrangle) o 1998 Delaware County Natural Areas Inventory Update reference: o “SP603, SP605, SP606, SP607, SP608, SP609, SP610” – Darby Creek Mouth Mudflat”- (Bridgeport Quadrangle)

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Description: This site consists of remnant tidal and riverbank in a highly modified portion of the Delaware River shoreline where Darby Creek meets the Delaware River opposite Little Tinicum . The mostly walled or rubble armored shoreline is dominated by a series of yacht clubs and small-boat marinas, but also includes some relatively undeveloped shoreline. Some of the piers do not appear to have been used in the recent past and are giving way to early successional . Along the river shoreline, native species of and animals compete with introduced species for the limited space and resources available for their use. Tidal mudflats are beginning to form in shallow areas at the base of the shoreline retaining walls and between marinas. The vegetation consists of tidal dominated by spatterdock and bulrushes, and adjacent areas of shallow dominated by tape-grass ( americana). The species composition is similar to that found across the on the mudflat and on the north side of Little Tinicum Island.

Species of Concern Considerations: The numerous plant species of concern found on the tidally influenced river shoreline can be grouped according their occurrence in relation to the high and low line. o Intertidal occurs at the upper edge of tidal inundation. Waterhemp ragweed, eastern baccharis, swamp beggar-ticks, beggar-ticks, bugleweed, shrubby camphor-weed, river bulrush, and Indian wild rice occur in this zone. o Intertidal freshwater mudflat is submerged during high tide and only exposed during low tide. Most plants are relatively short and often form clumps, and includes the plant species of concern little-spike spike-rush, Wrights spike rush, multiflowered mud-plantain, subulate arrowhead, and long-lobed arrow-head grow with leafy emergent vegetation such as spatterdock (), pickerelweed (Pontederia cordata), arrowheads (Sagittaria graminea, S. rigida), arrow arum (Peltandra virginica) and scattered patches of waterweed (Elodea nuttallii). o The tidal marsh also supports a sensitive species of concern, which is not named at the request of the jurisdictional agency overseeing their protection. This species depends on the continued cleanup and restoration of the marsh and aquatic habitat to survive.

Forest Cover / Natural Communities: The plant community types depicted are approximations delineated from 2005 aerial photography interpretation and were followed up with minimal selective ground-truthing. Community types follow “Terrestrial & Palustrine Plant Communities of Pennsylvania” (Fike 1999) where appropriate, and otherwise describe general land cover types (*). o Palustrine () communities: o Intertidal freshwater mudflat* o Intertidal freshwater marsh*

Ownership: o A small part of the shoreline is publicly owned as Governor Printz State Park, while the remainder is held in several relatively large private parcels. A large undeveloped portion right at the mouth of Darby Creek is owned by the Delaware County Industrial Development Authority. The reduced number of landowners can be helpful towards implementation of consistent conservation action of this piece of the landscape.

Habitat Disturbances: o Historic: o Most of the area between the I-95 freeway and the Delaware River has been greatly modified from the extensive system of tidal that used to dominate the shoreline. The tidally influenced shoreline of the Delaware River historically hosted expansive freshwater tidal marshes, especially at the mouths of the tributary creeks. Over the past several centuries and especially this past one, the marshes have been diked, ditched, drained, filled and converted to dry areas of commerce and residence. Most of this area is still within the of the

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river and is likely to be subject to future flooding from increasingly unpredictable weather patterns and an anticipated rise in level. o lines and roadways were built parallel to, and through the former marshes. o Industrial plants and a -fired electric generating plant were built on the banks of the river. o : o Much of the area remains as it was at the time of the 1937 aerial photos, with a series of small marinas lining the river , though upland development has filled most of the formerly sparsely developed area. Rapid development has occurred outside of and on the periphery of the core habitat area, fragmenting the landscape with additional buildings, roads and infrastructure and increasing the amount of and edge habitat in the immediate watershed. o In 2004 the oil tanker Athos-I hit an abandoned and uncharted anchor, ruptured its hull, and spilled 30,000 gallons of oil into the Delaware River. o The impact of wave action from passing boat traffic along this section of the river is buffered by Little Tinicum Island, which is likely the reason for its popularity as a small boat marina. o runoff from the highly developed surrounding communities flows into the creek system with little opportunity to be slowed or filtered. This results in increased downstream flooding and erosion and is a potentially significant non-point source of pollution. Runoff from these sources has significantly higher levels of , nutrients, pesticides, herbicides and other than runoff filtered through natural vegetation. o Exotic Species – This disturbed strip of vegetation is frequently dominated by invasive non- native trees such as tree-of-heaven, princess tree, Norway maple, Siberian elm, white poplar and white mulberry. Invasive shrubs and vines frequently dominate the understory including Japanese honeysuckle, porcelain berry, Asiatic bittersweet, multiflora rose, bush honeysuckles, common privet, barberry, paper mulberry and autumn olive to name a few.

Conservation Actions: o Future long range goals for this section of the river should be to simultaneously enhance the native of the riverfront as well as provide public access and park space opportunities. Since much of the Delaware River shoreline in Delaware County is currently transitioning from past industrial and shipping activity, the county is presented with an excellent opportunity to recreate a continuous greenway corridor along this stretch of the river. This linear area currently lends itself well to the reestablishment of a ribbon of native vegetation that will help provide habitat for native plants and animals while filtering and trapping runoff from the urban and suburban areas before it enters the river. In addition, the linear corridor can function as a portion of a public greenway along the length of the Delaware riverfront. Such a public amenity would greatly improve the quality of life for all residents and visitors to the area. o Future developments should be set back from the river shoreline to accommodate a 100-meter wide vegetated riparian buffer between the river’s edge and development activity. o The shoreline habitat can be improved by removing portions of the armored bulkheads and reconnecting the river to a portion of its natural floodplain. o Restore and protect the natural of the river and it tributaries. This may require that road crossings involve bridge systems that would preserve the wide sluggish associated with marshes and slow flowing waterways. o The undeveloped habitat on the north side of the mouth of the Darby Creek is owned by the Delaware County Industrial Development Authority. This parcel is currently well suited to ecological restoration activities. This parcel was undeveloped in 1937 air photos except for a few small-boat launch areas. Restoration activities could restore both tidal marsh and upland forest to this area. o Replant the riparian area in native trees and shrubs to enhance its ecological value. o Remove of plants. Control options for invasive plants range from mechanical to chemical. High priority for invasive species control at this site should be targeted towards Delaware County Natural Heritage Inventory 2011 – Darby Creek Mouth Mudflat /169

removing small populations of newly established invasive plants in the most weed-free areas of the Natural Heritage Area. Invasive species control efforts should try to maintain weed-free areas first, and then concentrate on removing invasive species in lightly infested areas, continually pushing back the line of invasion. Invasive species removal should be conducted in coordination with native species replacement to avoid denuding the understory vegetation. This needs to be a continual and sustained process of monitoring and control efforts.

Rocky Gleason (PNHP) Photo Source: Tidal mudflat vegetation is beginning to colonize the shallow waters at the base of retaining walls and between developed marinas in this section of the river shoreline.

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