Conewago Falls SAWMILL

Londonderry Township BECKER RD DAUPHIN TURNPIKE RD COUNTY Conewago Creek

Conoy Township LANCASTER 441 FALMOUTH RD COUNTY

KEENER RD

Snitz Creek BAIR RD

Newberry AMOSITE RD Township YORK COUNTY

York Haven 382 Boro

RIVER RD

Lancaster County Natural Heritage Inventory 2 Update 2008 nd

Legend NEWBERRY Species of concern core habitat Natural Heritage Area Roads East Manchester Supporting Landscape PA Turnpike Township Streams All other roads Riparian Buffer Municipal Boundary

Miles 0 0.25 0.5 1 Conewago Falls Conewago Falls – High significance

PNHP Rank1 Last State 2 Species of Concern: 1 Observed Quality Global State Status (y-m-d)

Plants: Aster-like boltonia (Boltonia asteroides) G5 S1 PE 2001-08-21 D Sedge (Carex shortiana) G5 S3 N 2001-06-18 CD Flat-stemmed spike-rush (Eleocharis G4 S1 PE 1991-09-09 C compressa) Waterpod (Ellisia nyctelea) G5 S2 PT 1996-05-06 B

Animals: Elktoe mussel (Alasmidonta marginata) G4 S4 - 2002-08-31 E Triangle floater mussel (Alasmidonta G4 S3S4 - 1999-08-06 E undulata) Yellow lampmussel (Lampsilis cariosa) G3G4 S3S4 - 2006-08-19 E Bronze copper ( hyllus) G5 SU - 1995-09-03 E Prothonotary warbler (Protonotaria citrea) G5 S2S3B - 2006-07 E Sensitive species of concern 3 - - - 2002 E

Exemplary Natural Communities Riverside Outcrop Community GNR S1S2 - 1992-07-07 CD

1 Please refer to Appendix IV for an explanation of PNHP ranks and legal status 2 Please refer to Appendix V for an explanation of quality ranks 3This species is not named at the request of the agency overseeing its protection

Location: This Natural Heritage Area encompasses the section of the Susquehanna River from the Safe Harbor Dam down river to Bainbridge. The focus is on the area of shallow water below the dam referred to as Conewago Falls and the eastern shore of the river. o Municipalities: o Conoy Township, (Lancaster County) o Londonderry Township, (Dauphin County) o Newberry Township, (York County) o York Haven Borough, (York County) o USGS Quadrangles: o Middletown Quadrangle o York Haven Quadrangle o 1990 Lancaster Natural Areas Inventory reference: o “Conewago Falls: NC511” (Middletown Quadrangle) o “Conewago Falls: SP509, NC513” (York Haven Quadrangle)

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Description: The Susquehanna River cuts though a diabase bedrock intrusion forming a low falls or rapids area with highly sculpted outcrops referred to as “potholes”. Seasonally fluctuating river levels alternately flood, scour and expose the bedrock boulders. Deposits of soil have filled cracks, crevices and depressions to provide a distinctive habitat for several species of plants uncommon to Pennsylvania. A wooded public walking trail is maintained by Conoy Township along the old canal towpath. The floodplain forest north of Bainbridge includes wetland habitats. The habitats of the river shoreline and floodplain would be compatible for an expanded passive recreation park system.

Species of Concern Considerations: Plants: o Aster-like Boltonia is adapted to the area of the river that is subject to periodic flooding, but usually remains well above the water line. This area includes the bedrock outcrops where plants colonize the cracks and crevices of the ice-scoured and flood-prone river shoreline. The species appears well-adapted to the seasonal fluctuations in water levels, especially the lower water levels of summer and fall when the plant is flowering and fruiting. The viability of populations of aster-like boltonia and its habitat depends on maintaining the natural hydrology and natural condition of the shoreline and islands of the lower Susquehanna River. Invasive species represent a threat to this species and its habitat. o Carex shortiana grows in wet meadows, bottomlands, swamps, or in moist woods, especially on calcareous (limestone) substrates. Creating buffers around wetlands, controlling invasive species, and protecting wetland hydrology will help to maintain occurrences of Short’s sedge. o Flat-stemmed spike-rush thrives in a sandy, silty or muddy substrate in shallow water at the edges of the islands and along the river shoreline. The viability of the known populations of this species will require maintaining the natural hydrology of the rivers, with the seasonal fluctuations and scouring, as well as retaining the natural conditions of the shorelines, riverbed outcrops, and islands. o Waterpod is a spring annual plant that grows on damp, shady stream banks with rich alluvial soils and sometimes in disturbed ground. The rich shady stream banks that ellisia depends upon are highly influenced by flooding events. Alteration of the natural flood cycle, dam building, increased erosion, and clearing of floodplain forests all affect the quality of suitable habitat. Populations are also threatened by loss of habitat from development and displacement by invasive plants. Protection of Ellisia will require maintenance of known populations and preservation of rich, shaded stream bank communities. This may include sustaining appropriate hydrology, removal of invasive plants, and establishment of buffers that can moderate the effects of scouring events and run-off. Management of the known sites requires long term monitoring of populations. : o Three freshwater mussel species of concern, elktoe, triangle floater and yellow lampmussel, along with four additional species of mussels were documented in this section of the Susquehanna River during surveys conducted by local naturalist, Larry Coble. Historically, the dwarf wedge mussel, a federally endangered species, was also documented as occurring in the Susquehanna River near this location. Mussels are filter feeders and are strongly impacted by poor water quality and unsuitable creek bed substrate. Mussels exist as a parasite on certain fish species in their early life stage, and decreased populations of the host fish can negatively affect mussel populations. Dams that impede fish migration also restrict the habitat available to mussels. All streams, creeks and tributaries to the Susquehanna River should have wide forested/vegetated buffers in order to help ensure proper water quality for freshwater mussel habitat. Impediments to fish movement such as dams and improper stream crossings should be corrected to improve available habitat for mussels and their fish hosts. o The principal habitat of the bronze copper butterfly is found in wet meadows and marshes especially along river floodplains. The primary food source of the caterpillars of this species are plants in the buckwheat family () such as peach-leaved dock (Rumex altissimus). Conservation and expansion of this type of habitat in the area will help ensure continued 216 Conewago Falls

breeding success for this species. Mowing of floodplain and riverbank areas should be discouraged, or selective and infrequent to help promote growth of host plants supporting this butterfly species of concern. o Prothonotary Warblers breed at several locations in this forested floodplain, which is intermediate habitat between the aquatic river habitat and the upland terrestrial habitat. The forested floodplain and associated wetlands along the Susquehanna River is the primary habitat for this species at this location. Because this bird nests in tree cavities, dead trees along the river shore and adjacent wetlands should be left standing to provide nesting habitat. o The river is habitat for a sensitive species of concern documented over several years at this location. Maintain and improve water quality and movement above dams for fish migration to improve the habitat for this species of concern. Exemplary Natural Communities: o Riverside Outcrop Community - This sparsely vegetated community is found on outcrops of circumneutral or calcareous rock along rivershores. Substrates are usually dolomite, limestone, or slate. Most are flooded annually at high water; this helps to maintain open conditions and also provides silt that accumulates in the rock crevices. The annual disturbance pattern of flooding and ice-scour restricts the vegetation to tough crevice-rooting herbs and low shrubs. Total vegetation cover is often less than 20%. Floristic composition can vary considerably (NatureServe, 2007)

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 The floodplain of the river is dominated by a silver maple-floodplain forest while the wooded uplands of the diabase bedrock are dominated by a tuliptree-beech-maple forest. o Terrestrial (upland) communities: o Tuliptree-beech-maple forest o Dry oak-mixed hardwood forest o modified successional forest* o shrubland* (mostly along powerline clearings) o Palustrine (wetland) communities: o Silver maple floodplain forest o Red maple-black gum palustrine forest o Red maple-elm-willow floodplain swamp o River birch-sycamore floodplain scrub o Red maple-mixed shrub palustrine woodland o Bluejoint-reed canary grass marsh o Cattail marsh o wet meadow*

Ownership: o The Commonwealth of Pennsylvania owns key portions of the river bedrock outcrops at this location. A river access boat ramp is maintained by the PA Fish & Boat Commission. o Conoy Township owns a narrow strip along the old canal towpath, which is maintained as a public walking trail. o PPL Corporation owns several larger parcels north of Bainbridge, including some wetland habitat, which it maintains as a nature preserve. o Norfolk Southern Railroad maintains an active rail line along the banks of the Susquehanna River. o Most of the remaining private property along the river floodplain and adjacent uplands is held in larger parcels. Future ownership fragmentation or parcel subdivision may impede conservation action. 217 Conewago Falls

Habitat Disturbances: o Historic – o Much of the original vegetation of the level expanses of land adjacent to the Susquehanna River had been cleared for agricultural production over several centuries. Large patches of forest remained where soil, slope, wetness or bedrock conditions prevented their conversion to agricultural uses. o Water quality of the river was severely degraded by direct pollution from sewage, industry, mining, agriculture and was exacerbated by the removal of most of the forest canopy within the upstream watershed at the turn of the century. o The York Haven Dam was constructed across the river contributing to limited migration potential for anadromous and catadromous fishes, which spend part of their lives in salt water and part of their lives in fresh water. Runoff from agricultural fields and erosion from all types of earth disturbances including coal mining has resulted in sediments being deposited behind the dam. Over time, the dam will be completely filled in with sediment from runoff. o The construction of many smaller dams on the Susquehanna River and its tributaries in the early 1800s severely reduced the American shad and other anadromous and catadromous fish from much of their traditional spawning streams. Many dams were breached in the late 1800s and the shad migration temporarily resumed. The construction of the series of four large hydroelectric dams on the Susquehanna River between 1904 and 1932 eliminated the American shad from the upper reaches of the Susquehanna almost to the close of the century. Fish trap and transport programs implemented during the 1970s moved fish upriver by trucks in an effort to bolster shad populations. Improved fish ladders were constructed on the Conowingo, Holtwood, Safe Harbor and York Haven dams in the 1990s to reopen the upper Susquehanna River for shad spawning. o With the elimination of anadromous and catadromous fishes from much of their historic range in the Susquehanna watershed, several species of freshwater mussels, which depend on suitable fish hosts for a portion of their lifecycle, also experienced declines. The total range of fish hosts for several mussel species is clearly understood, but recent studies indicate that the American eel may have been an important host for several mussel species. Since the eel is eliminated from much of the Susquehanna River, this may have led to considerable declines in mussel populations. o The railroad was built along the Susquehanna River. o Two milldams historically occurred along Snitz Creek. Milldams frequently trapped many tons of sediment behind them, altering the topography of the natural floodplain in the process. When the dams were breached, the streams frequently cut a deep channel through the accumulation of sediment. Portions of the creek remain trapped in these deep narrow channels. o Current – o The railroad along the Susquehanna shoreline impedes movement from the river to the uplands and visa versa, especially for small animals like turtles and salamanders that may consider the railroad an insurmountable obstacle. o The four hydroelectric dams on the Susquehanna River present the major obstacle to anadromous and catadromous fish migration. Recently installed fish ladders have improved the condition for anadromous fishes, but catadromous fishes continue to be excluded from the Susquehanna River watershed. o Several additional utility corridors were recently cut through the otherwise forested blocks on both shores of the river. o Residential development has replaced agricultural landuse in many areas and also is beginning to encroach on previously unfragmented forested areas. o Exotic Species – The natural disturbance of an active floodplain creates ideal conditions for many invasive species of plants, which are typically adapted to open, disturbed conditions. The 218 Conewago Falls

narrow linear canal towpath park is exceptionally infested with a number of aggressive invasive plants. Control efforts should be directed toward eradicating small populations of pioneer species, before they get established in the area. See fact sheets on invasive species for specific control options. Invasive plants to target for removal to improve the riparian habitat include: o Norway Maple (Acer platanoides) o Tree-of-heaven (Ailanthus altissima) o Common mugwort (Artemisia vulgaris) o Japanese & European barberry (Berberis thunbergii, Berberis vulgaris) o Asiatic bittersweet (Celastrus orbiculatus) o English ivy (Hedera helix) o Japanese honeysuckle (Lonicera japonica) o Bush honeysuckles (Lonicera morrowii, Lonicera maackii) o Common privet (Ligustrum vulgare, Ligustrum obtusifolium) o Purple loosestrife (Lythrum salicaria) o Japanese stilt grass (Microstegium vimineum) o Princess tree (Paulownia tomentosa) o Japanese knotweed (Polygonum cuspidatum) o Mile-a-minute (Polygonum perfoliatum) o Callery “Bradford” pear (Pyrus calleryana and its cultivars) o Jetbead (Rhodotypos scandens) o Multiflora rose (Rosa multiflora) o Wineberry (Rubus phoenicolasius)

Conservation Actions:

Overall: o Coordinate the protection of this landscape between Lancaster, Dauphin and York Counties. o Protect and expand the natural vegetation along both shores of the river floodplain and adjacent upland. Consider expansion of a wide strip of native vegetation as a terrestrial habitat corridor along both shores of the river. o Avoid building, replacing or expanding dams on the Susquehanna River. o Riparian corridors of all stream tributaries to this section of the Susquehanna River and the river shoreline itself need additional restoration measures. Several stretches of streams in this area lack vegetated riparian buffers and are nearly or fully unprotected from agricultural and urban runoff. o High water quality and appropriate substrate are both critical aspects to sustaining suitable habitat in this section of the river. Establish at least 100 meter (328 ft) buffer of woody vegetation along the river shore and 100 foot buffer along all segments of tributary streams to help protect the water quality of the river by reducing erosion, sedimentation, and pollution. Additionally, best management practices (BMPs) that focus on limiting nutrient and soil loss into surface and groundwater should be applied to surrounding agricultural lands. This would help maintain and improve water quality in the river. o Preserve the integrity of the adjacent unfragmented forested areas. Subdivision and fragmentation of large forested areas severely degrades its suitability to interior forest dependent species, such as many species of neotropical migrant songbirds. Most lands with diabase bedrock in this area had avoided past conversion to agricultural uses. Future development projects and subdivision should be discouraged within these habitats.

Within the Core Habitat: o Acquire larger parcels within the 100-year and secondary floodplains of the Susquehanna River. These areas would be compatible with a passive recreation park. Emphasis should be on promoting a viable floodplain natural community rather than construction of active park facilities and infrastructure. Mowing of the area should be minimized or eliminated 219 Conewago Falls

with special emphasis on protecting and expanding floodplain forest areas with native vegetation and restoration and protection of the natural condition of the shoreline. o Seek conservation easements on larger parcels within 300 meters of the river floodplain. o Stormwater runoff from agricultural fields, residences, industry and roadways should be considered a potential source of significant contamination for the river. Runoff from these sources have significantly higher levels of sediment, nutrients, pesticides, herbicides and other pollutants than runoff filtered through a natural habitat. Stormwater management measures such as the creation of detention basins or vegetated swales should be implemented to intercept runoff at its source and at road crossings or other breaks in the vegetated buffer. o Provide periodic culverts or other crossing opportunities for small animals to traverse the railroad tracks from river to uplands and visa versa. Care must be taken not to inadvertently drain the wetlands north of Bainbridge due to culvert construction.

Within the Supporting Landscape: The supporting landscape was drawn around the 100 meter riparian buffer of all tributaries leading to this stretch of the Susquehanna River. It also includes a 300 meter buffer from the 100-year floodplain of the Susquehanna River itself. Activities and land use patterns in these areas can have a significant impact on the water quality of the river and the habitats of the species of concern. o The long term goal for the area should be to restore mature floodplain forests and the associated upland buffer forests along the river. Expand the native vegetation along the river corridor to include land within 300 meters of the river’s banks. Reforestation efforts should be designed to mimic the adjacent natural community type by planting a similar composition of native trees and shrubs of varying age classes. Reforestation is a labor intensive effort that requires long term monitoring and maintenance to avoid infestation by invasive species of plants. o Riparian buffers of stream tributaries to this section of the Susquehanna River and the river shoreline itself have substantial forest/natural vegetation cover. With moderate effort to extend these attributes to the recommended width, these riparian buffers could become very good examples of restored/conserved riparian habitat corridors for this portion of the county. o Conoy Township has a zoning ordinance restricting new construction within the 100-year floodplain of all waterways. Strict enforcement of this regulation will help prevent conversion of the floodplain to many unsuitable uses and help protect most of the species of concern core habitat. o Floodplain regulations should be updated to prohibit agricultural activities within the 100-year floodplain as well. Chemical, nutrient and sediment runoff into waterways from agricultural sources can be significantly reduced by returning seasonally flooded areas to natural habitats. o Potential restoration activities: o Two milldams occurred on Snitz Creek. An analysis of the legacy sediments these dams trapped and the feasibility to restore the original topography should be conducted prior to replanting efforts. o Streams through forested areas should be considered high priority for conservation. The forested riparian corridor helps to regulate the temperature of the stream and creates streamside conditions that contribute to improved water quality and aquatic habitat. Streams through non-forested areas should be reforested with native trees and shrubs appropriate to the habitat. o Careful determination is needed to avoid planting trees in floodplains that contain herbaceous wetland habitats. These habitats should be maintained in their current open condition, with tree plantings to occur at the periphery of natural wetland openings.

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o Take into account the presence of legacy sediments at historic milldam locations and appropriately restore the historic floodplain as feasible. o Priorities for restoration of historic floodplain topography should be where the end result would be a functioning wetland habitat. o An ideal forested stream buffer should be at least 100 meters in width from the upper edge of the 100-year floodplain. o An intermediate forested stream buffer should be at least 100 feet in width from the upper edge of the 100-year floodplain. o A minimum forested buffer should be at least 35 feet in width from the upper edge of the 100-year floodplain. o Remove invasive species of plants. The river floodplain and areas of past agricultural activity are naturally susceptible to weedy plant invasion and will require a sustained and targeted approach to invasive management. Aggressive invasive species along the floodplain can have a significant impact on the available habitat for native species, which can occupy much the same habitat as purple loosestrife and Japanese knotweed. Control of invasive species along the river floodplain will require extensive and continual effort. Focus non-chemical control efforts on selected areas surrounding species of concern. o Target pioneer populations of invasive plants for immediate and continued removal, particularly tree-of-heaven, non-native bush honeysuckles, Japanese honeysuckle, multiflora rose, jetbead, Asiatic bittersweet and common privet. It is much easier and more effective to keep a place invasive-free than to try and repair a heavily infested habitat. o Invasive species management needs to be coordinated by individuals familiar with native species as well as the invasive species present. o Continual invasive species monitoring and control will be necessary. o Remove and monitor illegal dumps. Litter removal along the shore of the river will need to be conducted on a periodic and continual basis due to the seasonal flooding regimen of the river.

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