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Conejohela Flats COLUMBIA AVE West Hempfield Township 462 Columbia Boro

Wrightsville Boro

441 FRANKLIN RD

Hellam Township

Lower Windsor Township

Manor Township

PENN ST (LimitAerialof imagery)

RIVER RD

Susquehanna River

East Prospect

Lancaster County Natural Heritage Inventory Update 2008 Legend LOWER WINDSOR Species of concern core habitat Natural Heritage Area Roads Supporting Landscape PA Turnpike Streams All other roads 425 Riparian Buffer Municipal Boundary Chanceford Township LANCASTER Miles YORK COUNTY 0 0.25 0.5 1 1.5 2 COUNTY Conejohela Flats Conejohela Flats – Exceptional significance

PNHP Rank1 State Last Observed Species of Concern: Quality2 Global State Status1 (y-m-d)

Plants: Scarlet ammannia (Ammannia coccinea) G5 S2 PE 2003-08-15 B Tooth-cup (Rotala ramosior) G5 S3 PR 2003-08-15 B

Animals: Great Egret (Casmerodius albus) G5 S1B PE 1986 F Prothonotary Warbler (Protonotaria citrea) G5 S2S3B - 1989-06-02 B Sensitive species of concern-(A)3 - - - 1991-05-18 E Sensitive species of concern-(B)3 - - - 2003 E Sensitive species of concern-(C)3 - - - 1989-06-02 E Sensitive species of concern-(D)3 - - - 1987 E

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 3 This species is not named at the request of the agency overseeing its protection

Location: This Natural Heritage Area describes the section of the Susquehanna River and the adjacent banks between the Columbia – Wrightsville Bridge down river to Turkey Hill, south of Washington Borough. The water level of this section of the river is impacted by Safe harbor Dam, which forms this slow water area referred to as Lake Clarke, a popular area for recreational boating. o Municipalities: o Manor Township, (Lancaster County) o West Hempfield Township, (Lancaster County) o Columbia Borough, (Lancaster County) o Washington Borough, (Lancaster County) o Chanceford Township, (York County) o Hellam Township, (York County) o Lower Windsor Township, (York County) o Wrightsville Borough, (York County) o USGS Quadrangles: o Columbia East Quadrangle o Columbia West Quadrangle o Red Lion Quadrangle o Safe Harbor Quadrangle o 1990 Lancaster County Natural Areas Inventory reference: o “Rookery Islands (Conejohela Flats)” – (Columbia East Quadrangle) o “Rookery Islands (Conejohela Flats)” – (Safe Harbor Quadrangle)

Description: Conejohela Flats is a combination of small brushy islands and mud flats located in the Susquehanna River just west of Washington Borough. The series of islands and the shoreline are periodically

189 Conejohela Flats disturbed by seasonal flooding and scouring by ice. The mud flats are also exposed when the water level is lowered by the Safe Harbor Dam to generate electricity. This area has been designated an Important Bird Area by the Pennsylvania Audubon Society primarily because the mud flats provide an important habitat for shore birds that is found in few other locations in Pennsylvania. A rookery, (a concentrated breeding area for birds), exists within the island habitat. Many other species of wetland birds and waterfowl also use this area during migration. During one survey, 73 species of wadding birds, ducks and shorebirds were observed. Grassy flats and gravel bars are important for feeding and resting during both spring and fall migration. The adjacent uplands and forested slopes are an important aspect of this Natural Heritage Area, as these terrestrial habitats provide essential nesting and breeding locations for several of the species of concern.

Species of Concern Considerations: Plants: o Scarlet ammannia is a globally secure (G5) though state imperiled (S2) plant that inhabits various damp to wet habitats, especially on the shorelines of rivers, streams, and ponds, and may also be found in human-created disturbances that simulate natural habitats. The core habitat for this species is primarily along the damp edges of the islands, mudflats and shallow water areas. The higher elevations of the islands are not considered part of the primary habitat for this species. Conservation of this habitat type will help this species persist at this location. o Tooth cup is a globally secure (G5), state rare (S3) annual plant that occupies exposed shorelines, stream margins, streambed outcrops, and other damp, open places. The populations of toothcup that occur along streams and rivers can be enhanced by maintaining the natural seasonal fluctuations in the water level of the stream and the natural conditions of its shoreline. The core habitat for this species is primarily along the damp edges of the islands, mudflats and shallow water areas. The higher elevations of the islands are not considered part of the primary habitat for this species. Animals: o Prothonotary Warblers were documented successfully nesting for much of the 1980s. Recent records for this bird’s success at this location are lacking. The islands and the adjacent floodplain forests are the primary habitats 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. Recreational boaters can have a significant negative impact on the breeding success of this species. Harassment of nesting locations can cause adults to abandon the site. A buffer from boating activities needs to be established around nesting locations during breeding season to help prevent inadvertent conflict. o Great Egret was observed successfully nesting at this location in 1986, but has not been documented recently. This area was considered a failed breeding location for this species in 1988 and 1989. Though the species has been regularly observed in the area, only breeding occurrences are considered as core habitat for bird species of concern. Regular breeding season surveys of the area should be conducted with consideration of the potential to disrupt nesting behavior. Recreational boaters can have a significant negative impact on the breeding success of this species. Harassment of nesting locations can cause adults to abandon the site. A buffer from boating activities needs to be established around nesting locations during breeding season to help prevent inadvertent conflict. o A sensitive species of concern (A) utilizes the steep, dry, southwest-facing wooded slopes along the Susquehanna River. The suitable habitat for this species is mapped as occurring from Turkey Hill all the way down to the mouth of the Conestoga River. The core habitat for this species overlaps with the Fry’s Run Slopes Natural Heritage Area. A dead specimen was found between the two rails of the train tracks along the river. The railroad can be a substantial barrier for small animal movement between upland and lowland habitats. Periodic under-track culverts, or other means of mitigating the barrier effect of the tracks, should be integrated into future railroad maintenance plans.

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o Several populations of three additional sensitive species of concern (B, C & D) were documented along this stretch of the river. The core habitat for these sensitive species of concern is both the river and the adjacent upland forest. These sensitive species of concern require abundant food source in the river and its tributaries as well as breeding areas in the adjacent upland forest. This can be achieved by preserving and improving the water quality of the Susquehanna River and by protecting and expanding the natural vegetation buffer along the river and all its tributaries. Recreational boaters can have a significant negative impact on the breeding success of these species. Harassment of nesting locations can cause adults to abandon the site. A buffer from boating activities needs to be established around nesting locations during breeding season to help prevent inadvertent conflict.

Forest Cover / Natural Communities: The plant community types depicted are only 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 describe general land cover types where they are not (*). o This Natural Heritage Area is drawn tightly along the banks of the Susquehanna River, with most of the area in the river itself. The natural communities are primarily associated with the river floodplain, which is dominated by silver maple floodplain forest and river birch-sycamore floodplain scrub. Lower islands have expanses of grassy flats and sand/gravel bars. o The western shore of the river and the adjacent uplands have significant patches of forest cover including several interior forest blocks. o The Lancaster County side of the river is dominated by agriculture, urban and suburban land uses with only a few small parcels of forest cover remaining. The floodplain between the railroad tracks and the river is seasonally flooded and contains remnants of a silver maple floodplain forest. o Terrestrial (upland) communities: o Red oak-mixed hardwood forest o Hemlock-tuliptree-birch forest o Dry oak-heath forest o modified successional forest* o Palustrine (wetland) communities: o River birch-sycamore floodplain scrub o Silver maple floodplain forest

Ownership: o Much of the species of concern core habitat occurs in floodplain habitat that is subject to such intense flooding that it should be considered part of the river. o Most of the islands in the river are owned by Safe Harbor Water Power Corporation, and many contain areas leased for seasonal cabins. Safe Harbor also owns several parcels along the river shoreline. o Lancaster County Conservancy owns a forested parcel just north of Turkey Hill. o The Norfolk Southern Rail Corporation owns a rights-of-way paralleling the shore of the Susquehanna River. o The Lancaster Area Sewer Authority owns several large parcels just south of Washington Borough. o Much of the undeveloped floodplain and upland shoreline is owned by a number of private property owners and maintained in agricultural production.

Habitat Disturbances: o Historic – o The original forest cover of the area had been removed and converted to agricultural uses over the past several centuries, leaving little of the original vegetation in place on the

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Lancaster County side of the river. Portions of the York County side of the river remains in natural forest cover likely due to the steepness of the terrain. Where the topography was flat enough, first agriculture then suburban development replaced the original forest cover. The boroughs of Columbia, Wrightsville & Washington were constructed on the banks of the river including a portion of the floodplain. Additional narrow areas along the river shoreline were developed on both sides of the river, especially Long Level Road in York County. o Aerial photographs from the 1940s show that many of the smaller islands, which were less affected by flooding than the larger ones, were mostly cleared and used for agriculture. o Safe Harbor Dam was built in the early 1930s to create electric power. As the water backed up to create Lake Clarke, shallow water habitats and many smaller islands were permanently flooded. 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 fish (which live in the ocean, but spawn in freshwater) from much of their traditional spawning streams. Catadromous fish such as American eel, which live in fresh water habitats but spawn in the ocean, were also severely affected by dams large and small in the Susquehanna River watershed. Many dams were breached in the late 1800s and the fish migration temporarily resumed. The construction of the series of four large hydroelectric dams on the Susquehanna River between 1904 and 1932 eliminated the anadromous and catadromous fish 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 Holtwood and Safe Harbor dams in the 1990s to reopen the upper Susquehanna River for shad spawning. Effective downstream fish passages for eels have not been developed and eels remain eliminated from their historic range in the Susquehanna watershed. o Railroad tracks were built along the shoreline of the river, effectively severing the river from much of the original floodplain and the adjacent uplands. o Current – o The four hydroelectric dams on the Susquehanna River provide 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 of the islands are heavily populated with leased seasonal cabins. The habitat of the islands is significantly degraded by the density of cabins, their outbuildings, docks and debris. Recent aerial photographs show the islands as flooded. These flooded seasonal residences can contribute significantly to the contamination of the Susquehanna River. o The railroad along the Susquehanna shoreline impedes animal movement from the river to the uplands and visa versa, especially for small animals like reptiles, amphibians and small mammals that may consider the railroad an insurmountable obstacle. o Residential development has increased along the York County side of the river. o Many small towns, cottages and residences have been built along the both shores of the river, disturbing, altering and removing the natural river shore floodplain habitat. o Recreational boaters can have a significant negative impact on the breeding success of nesting birds. Harassment of nesting locations can cause adults to abandon the site. A buffer from boating activities needs to be established around the large islands during breeding season, which host most of the nesting locations, to help prevent inadvertent conflict. Wave action from motorboats can also have an impact on the shallow water habitats in the area. Increased wave action can dislodge small plants from mudflats.

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o Turkey Hill, to the north of the Natural Heritage Area, has been developed as a landfill for Lancaster County. o Garden debris and other refuse dumped into the river floodplain can be a significant source of invasive plant species and general habitat degradation. o Exotic Species – o The river floodplain is naturally susceptible to weedy plant invasion. The railroad rights- of-way and the transition zone between forested and agricultural landscapes are also areas of greatest invasive plant species concentrations. The river’s edge is particularly susceptible to invasion by purple loosestrife and Japanese knotweed, which are common invaders of wetland edges.

o Tree-of-heaven1 (Ailanthus altissima) o Mile-a-minute (Polygonum perfoliatum)

o Multiflora1 rose (Rosa multiflora) o Common mugwort (Artemisia vulgaris)

o Japanese1 honeysuckle (Lonicera japonica)

o Japanese1 knotweed (Polygonum cuspidatum)

o Purple1 loosestrife (Lythrum salicaria) o Japanese hops (Humulus japonicus)

Conservation Actions:

Overall: o Coordinate the protection of this landscape between Lancaster and York Counties. o Prevent fragmentation and incursions into the forested landscape. 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 the eastern shore of the river. Encourage agricultural areas along the banks of the river and its adjacent bluffs to retreat from the river’s edge and to revert to a forested landscape. The forested landscape helps to protect the water quality of the small streams that drain through this Natural Heritage Area into the Susquehanna River and provides refuge and habitat for other forest dependent species. o Avoid building, replacing or expanding dams on the Susquehanna River. o While many sections of tributaries to the Susquehanna River here have adequate vegetated riparian buffers, many sections of streams, as well as the river shoreline itself, need additional restoration measures. Numerous stretches of streams in this area lack vegetated riparian buffers and are nearly or fully unprotected from agricultural runoff. High water quality and appropriate substrate are both critical aspects to sustaining suitable habitat in this section of the river. Establish a 300-meter buffer of native woody vegetation along the Susquehanna River shore where open space exists and a 100-meter vegetated 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 Suppress the establishment and spread of invasive species of plants. o Encourage the regeneration of native trees, shrubs and herbaceous layers. The forest cover of the river slopes should be allowed to achieve and maintain old-growth characteristics.

Within the Core Habitat: o Discourage the establishment of seasonal cottages and year-round residences along the river shoreline and river islands. Limit and reduce the number of seasonal cabins on the shoreline and islands of the river. There are currently too many seasonal cabins on many of the islands, particularly Mud Island, Garden Island and Heises Island. Septic systems for these structures

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are frequently inadequate or nonexistent. Disturbance on shorelines and islands includes loss or impairment of critical habitat due to construction of cabins, access roads, boat docks, lawns and vegetation clearing. Some vegetation removal can be beneficial to the habitat, but an increase in island or shoreline cottages can only result in a decrease in habitat for species adapted to these specific habitat conditions. The floodplain habitat of the river would be improved by the removal of the residences within the floodplain. The island habitat would be improved by the removal of seasonal cabins.

Within the Natural Heritage Area / Supporting Landscape: o Most of the conservation actions for the core habitat also apply to the supporting landscape. o The long term goal for the area should be to restore mature floodplain forests and the associated upland buffer forests along both shores of 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 recruiting 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 Avoid additional fragmenting features such as roads, buildings, & utility rights-of-way especially along the river shoreline and any large forested blocks. Preserve and improve the integrity of the large unfragmented forest blocks on the western shore of the Susquehanna River. These large forested areas provide a significant filter for runoff entering the river from these slopes. The steep, rocky nature of the wooded slopes likely precludes most types of development activity. The flatter hilltops, however, could prove tempting building sites. Avoid activities that would fragment this habitat or create more edge areas, such as road building, which encourage the introduction of invasive plants or edge-adapted species and diminish the habitat available to interior forest dwelling species. o Avoid logging activities on slopes adjacent to the Susquehanna River to allow for the development of old growth conditions. The immediate watershed draining into the river includes some forested areas and agricultural fields. Logging of wooded areas, specifically along steep slopes and riparian borders would be detrimental to the watershed. Nutrients from agricultural fields, failures from septic systems within the watershed, lawn care fertilizers and other sources can accumulate in the river leading to algal blooms and the consequent death of aquatic organisms. The amount of impervious surfaces around the river can allow all types of chemical runoff from roads, building materials etc. to reach and contaminate the river. o The habitat of the shoreline floodplain would be improved by the removal of residences within the floodplain of the river. o Pursue conservation easements and fee simple acquisition on properties along the river shoreline, the adjacent slopes and forested plateaus to help conserve the effectiveness of the Susquehanna River natural corridor. o Potential zoning options for conservation enhancement: o Manor and West Hempfield Townships have zoning ordinances restricting new construction within the 100-year floodplain of all waterways. Strict enforcement of these regulations will help prevent conversion of the floodplain to 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 Strict enforcement of regulations restricting building activity on slopes1 greater than 25% would help prevent the forested slopes from being converted to other uses. o Zoning regulations should discourage further fragmentation of contiguous or interior forest blocks. Parcels currently forested should be zoned to conserve this attribute.

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o Parcels currently in agriculture that are of high quality agricultural soils should be zoned agricultural and considered fully built-out. Poorer quality agricultural soils should be encouraged to regenerate into forest cover. o Growth within the Township should be discouraged to occur within 300 meters of the 100-year floodplain of the river or within 100 meters of the floodplain of its tributaries. o Growth should be encouraged to occur clustered in close proximity to existing infrastructure to avoid unnecessary habitat destruction, particularly along the shoreline of the Susquehanna River. o Potential restoration activities: o Streams through forested areas should be considered high priority for conservation in the habitat. 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. 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. o Ideal forested stream buffers should be 100 meters (~300 feet) in width from the edge of the 100-year floodplain o Intermediate forested stream buffer of 100 feet in width from the edge of the 100-year floodplain o Minimum forested buffer of 35 feet in width from the edge of the 100-year floodplain o Remove invasive species of plants. The river floodplain is naturally susceptible to weedy plant invasion and will require a sustained and targeted approach to invasive management. o Target pioneer populations of invasive plants for immediate and continued removal, particularly tree-of-heaven, non-native bush honeysuckles, Japanese honeysuckle, Japanese hops, multiflora rose 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 are a significant feature of the railroad rights-of-way and river shorelines. However, indiscriminate use of herbicides as rights-of-way defoliants is not acceptable. A smarter, more selective use of chemical controls is required in these areas that contain both invasive species and species of concern. o Invasive species management needs to be coordinated by individuals familiar with the rare species as well as the invasive species present. o Continual invasive species monitoring and control will be necessary.

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