This section is meant to apply scientific principles to studies of The Sparkill Creek to gauge the current environmental conditions. It is also meant to be used as a tool for determining the optimal way to restore the creek. The 2003 New York State Department of Environmental Conservation (NYSDEC) Biological Assessment became the most informative study of The Sparkill Creek to date. The study was lead by Robert Bove and Margaret Novak who are two of the most experienced and qualified environmental professionals in The State of New York. For these reasons, their report will be the main reference of this section on Environmental Science.
Bioassessments
A useful method of gauging the health of an aquatic environment is by collecting samples of macroinvertebrates. The mayfly (Ephemeroptera), stonefly (Plecoptera), and caddisfly (Trichoptera) are popular macroinvertebrate bioindicators. They are aquatic organisms that are generally intolerant of water pollution, their absence is typically indicative of contamination. All three of these species quantify EPT Richness. The stonefly Eccoptura Xanthenes is rare to southeasten New York, yet a Columbia University scientist found it to be present in the Clausland Mountain area of the creek indicating good water conditions.The 2003 NYSDEC Biological Assessment indicated the presence of all three EPT species at the Blauvelt sampling location. A sensitive caddisfly that was found in abundance at the Blauvelt sampling location was found to be absent downstream at the Orangeburg sampling location. Interestingly, stoneflies did not appear in any more of the downstream samples beyond Blauvelt. Furthermore, mayflies were absent in the Sparkill Gap. This data suggests that the water is being adversely impacted beyond the Blauvelt sampling location, and is being further impacted downstream. At the Sparkill sampling location, elevated quantities of Black Fly larvae were discovered. According to the EPA, this is an indicator of too many nutrients such as nitrogen and phosphorus in the water.
As the wastewater treatment plant occasionally releases untreated sewage into The Sparkill Creek, one would expect the downstream ecology to be altered by the exposure to organic waste. This was validated by the 2003 NYSDEC Biological Assessment. Sewage-tolerant worms and midges were found to be plentiful in the Tappan sampling location. This data suggests that organic waste has had an impact on the aquatic environment two miles downstream from the plant. Additional sampling is warranted in between the plant and the Tappan sampling location to determine if a relationship exists.
Evidence of Bioaccumulation
In 1998, the Stream Biomonitoring Unit of the NYSDEC found that elevated levels of pesticides, metals and Polycyclic Aromatic Hydrocarbons (PAH's) existed in Caddisfly tissue. PAH's and selenium were confirmed the following year in samples from both Sparkill and Tappan. In 2002, The NYSDEC's Rotating Integrative Basin Studies (RIBS) team collected samples from the creek. What is both interesting and indicative from the 2002 RIBS assessment is the contrast between the assessments of Tappan and Sparkill. Tappan was assessed as having "organic waste and nutrient enrichment impacts" while Sparkill had "toxic impacts." This is due to the fact that copper, lead, selenium and titanium were found in the invertebrates in Sparkill. These metals have the potential to enter into the food chain, including the birds of the Piermont Marsh.
Nutrient Enrichment
Nutrient enrichment is the second leading cause of impairment of lakes and streams and there no question that it is occurring in The Sparkill Creek. Nutrient enrichment of a waterbody from phosphorus and nitrogen often results with the overgrowth of benthic algae in shallow, faster currents and an over-abundance of phytoplankton and macrophytes in the slow current areas of rivers and streams (Wang, 2006). After these plants die off, the aerobic bacteria that break them down flourish causing the levels of dissolved oxygen to drop. Sampling in 2002 found nitrate and phosphorus levels above natural conditions, which confirmed data gathered ten years prior. In the 2003 NYSDEC Biological Assessment, filamentous algae was absent in the Blauvelt and Orangeburg sampling locations yet it was present in the Tappan and Piermont locations. This data provides further evidence that nutrient enrichment is taking place and increasing downstream.
“Algae covers 100% of the substrate (in the Sparkill Gap)…algae growth in the Sparkill appears to be chronic rather than episodic. It would appear that phosphorus and nitrates are providing nutrients that aid the proliferation of algae in the Sparkill. While the source of these substances is unknown, they frequently originate from urban runoff and sewage effluent.” –Nolan, 2002
The overgrowth of algae on the substrate of the Sparkill Creek is something that has been documented for quite some time now. In 1993, Stevens and Schmidt noted heavy growth of algae and bacteria occurring on the substrate surfaces. This was reaffirmed in 2002, 2003 and again in 2009. In the summer of 2008, a member of The Sparkill Creek Project reported seeing evidence of algal blooms in the Ferdon Mill Pond. This member also reported seeing bright green algae on substrate in the Ferdon Mill Pond the following winter.
Erosion & Siltation
In 1999, a study on the flooding in the Sparkill watershed was performed by the independent engineering firm Goodkind and O'Dea Inc. They confirmed that erosion and sedimentation was taking place and attributed it to the development of the watershed. The 2003 NYSDEC Biological Assessment would note that as The Sparkill Creek flows from Blauvelt to Sparkill, the percentage of gravel and rubble (0.2cm-25.4cm) steadily decreases. At the same time the percentage of silt and sand (0.004mm-2.0mm) steadily increases. This is indicative of the erosion that has taken place. The overdevelopment of The Sparkill Creek watershed has caused an influx in the quantities of dissolved and suspended solids in the water, which leads to increased turbidity and total solids. The effects of this include a reduced concentration of dissolved oxygen, habitat loss and the loss of plant and animal life. High turbidity can have a negative impact on submerged aquatic vegetation and benthic organisms by obstructing sunlight and smothering eggs and larvae. In addition, the water levels rise as the creek fills with an increasing amount of sediment which provokes flooding and further erosion. In 2009, the founder of the Sparkill Creek Project noted evidence of erosion occurring in every town. It is believed that during periods of high flow and accelerated currents, silt, sediments and biomass become suspended and settle in wider and slower flowing areas of the creek like the Ferdon Mill Pond. The periods of high flow have drastically altered the width and the depth of the creek. As a result of several floods, the width of the creek has increased causing the depth of water to decrease as sediment is displaced from the banks to the creek bed. During a March 2009 study of fish in the creek, it was found that the larger species of fish prefer the areas of the creek that are several feet in depth. Erosion and siltation throughout the creek have made such areas few and far between.
A good relationship between a stream and it's floodplain is important to maintain stability and function. When this relationship is disturbed, a stream enters a destructive process that greatly alters many of it's natural characteristics. In the case of The Sparkill Creek, the development of the watershed caused an increase in stream power. This caused a deepening of the creek bed also known as channel incision, which is clearly visible between Northvale and Piermont. Although channel incision is a natural phenomenon, when it occurs frequently and excessively due to man-made alterations to the watershed it can be very damaging to aquatic life. By lowering the elevation of the creek bed, the access to the floodplain during times of high flow becomes limited This causes the stream banks to erode further and makes them become oversteepened and unstable. This leads to the failure of the stream banks which widens the diameter of the stream and deposits alluvium onto the bed. The elevation of the water drops more as this alluvium is washed downstream and the interaction with the floodplain decreased further. This is what has occurred with parts of The Sparkill Creek and is seen clearly in wetland areas because that is where the creek had evolved to overflow. Most of the silt deposited in the Ferdon Mill Pond is believed to have once been part of the stream banks.
Erosion and siltation in the creek have been associated with areas where it is visibly taking place. It is believed that there is also a significant amount of siltation occurring in The Piermont Marsh where it has yet to be studied and may not be so visible. During periods of low tide, it is apparent that the deposition of sediments is altering the shape of the channels within the marsh. The degree to which this is occurring and the effects on the fauna are unknown at the time and warrant additional investigations.
Water Chemistry
The 2003 sampling showed fairly constant temperature levels and Ph levels throughout The Sparkill Creek. There was a spike in conductivity of 100% between the Blauvelt and Orangeburg sampling locations. Organic ions such as phenols, oil, alcohol and sugar, can decrease conductivity while phosphate and nitrate content can increase conductivity (EPA,1997). Specifically, conductivity is an indirect measure of the presence of dissolved solids such as chloride, nitrate, sulfate, phosphate, sodium, magnesium, calcium, and iron, and can be used as an indicator of water pollution (USGS, 2007) . The data from the 2003 sampling suggests that as the creek flows through residential Blauvelt and Orangeburg, it begins to collect runoff that likely contains fertilizers. Beyond that point, conductivity remained little changed. Conductivity between 150 and 500µS/cm is considered a good mixed-fisheries range (EPA, 1997). Conductivity outside this range could indicate that the water is not suitable for certain species of fish or macroinvertebrates (EPA,1997). The conductivity of The Sparkill Creek was found to be 362µS/cm at the the Blauvelt sampling location which would suggest an optimal level of conductivity for fish. Downstream the conductivity ranged from 737µS/cm to 815µS/cm suggesting that is difficult for certain species of fish and macroinvertebrates to survive there.
Dissolved oxygen (DO) is oxygen gas (O2) that is dissolved in water. The DOlevel is a function of water turbulence, diffusion, and plant respiration. The levels of dissolved oxygen were highest in Blauvelt and lowest in Sparkill. Despite the lower amounts of DO downstream, the overall range of 7.6 mg/l to 8.8 mg/l is considered suitable for freshwater fish. DO goes up in the winter and in the late winter of 2002, the DO level in Sparkill was found to be 10.6 mg/l. This is reassuring considering the number of factors acting on the Sparkill Creek that influence a lower DO level. The data suggests that despite the level of nutrient enrichment, erosion, and organic pollution, the DO level is still suitable to support aquatic life. The data also suggest that if the DO level is around 7.6 mg/l to 8.8 mg/l in the current summer conditions, there is the potential to see a much higher range of DO once the proper action is take. DO levels higher than the current are more likely to support the development of fish larvae.
The separate 2002 study concluded that "The pH, alkalinity, water temperature, and dissolved oxygen readings all were within the parameters for a healthy stream." Conductivity and turbidity were found to be at slightly elevated levels. All of water chemistry data is directly correlated with the results of the bioassessments. This further supports the NYSDEC’s conclusion that water quality decreases linearly downstream.
Pollution from Watershed
The watershed of The Sparkill Creek begins in a forested area with only a minor amount of development. Only two roads and one residential development exist within the Clausland Mountain section of the watershed. There are a very minimal amount of anthropocentric influences acting on the creek in Clausland Mountain. As the creek enters Blauvelt and Orangeburg, it receives direct runoff from the adjacent residential properties. This half mile stretch is one of the suspected sources of nutrient enrichment. As the creek flows through commercial and industrial areas for the next two miles, it is likely receiving pollutants directly from Route 303 runoff and from drainage pipes. These pollutants are believed to be hydrocarbons associated with automobiles. This area is also likely to receive litter from the high vehicle traffic along Route 303. When the wastewater treatment plant dumps untreated sewage into the creek it is certain that nutrients and bacteria are introduced, and is likely additional pollutants do as well. As the creek enters Tappan, runoff from the adjacent residential properties are likely introducing additional nutrients. The exposure to the commercial area of Tappan and Northvale is limited, yet possibly detrimental to the health of the creek. It is likely that hydrocarbons and possibly solvents are entering the creek at this point. Beyond this point the creek is fed by two tributaries that run through golf courses. These tributaries have a high probability of collecting herbicides, pesticides and fertilizers considering the size of the golf courses and the condition of the grass that is needed for recreational and aesthetic value. As the creek heads northeast to The Hudson river, it runs adjacent to residential Sparkill and residential Piermont where additional nutrient loading is likely.
Chloride contamination from the runoff of the streets may be unintentional, but it is widespread. The 1993 study by Hudsonia documented chloride contamination in the creek. When salt is applied to snow and ice, the saline water that results gets into the creek. Freshwater organisms are called such because they need freshwater to live. When massive amounts of salt enters the creek as it does, it makes it difficult for freshwater organisms to survive. Chloride contamination has been the subject of many environmental studies. Even if a road is salted at a distance from the surface water, it has the potential to find the groundwater which will later find the creek. The good news is that should the saline water make it into the sewer rather than the creek, even if it were untreated, it would be discharged into the saline Hudson River and end up in The Atlantic Ocean.
After obtaining a copy of the analytical results of the 2007 sampling of the Ferdon Mill Pond silt, it became apparent that the contamination is not severe by any means. In fact, the analytical results of the six samples that were collected were only found to have minimal amounts of Semi-Volatile Organic Compounds. These compounds and the concentrations in which they were detected are typical of urban fill and do not necessarily represent an impacted medium. The lack of metals and other contaminants of concern suggest that the actual impacts to the sediments in the creek bed are limited in the Ferdon Mill Pond. Considering that this area acts as a filter for the creek because of the low velocity and high algae content, it is suggestive that the impacts to the sediment in the entire creek are limited. The sampling of sediment upstream is necessary to confirm this claim.
Fish
The dams that were constructed in Piemont in the 18th century drastically altered the ecology of The Sparkill Creek. The larger dam prevents fish from The Atlantic Ocean and The Hudson River from spawning beyond that point. This was damaging to the predators of the upper Sparkill Creek ecosystem that may have otherwise consumed such eggs, larvae and fish. An interesting aspect of the larger dam though is that today, it likely prevents invasive species that exist in The Atlantic Ocean and The Hudson River from entering the upper creek area. The Chinese Mitten Crab is an invasive species that was the subject of a 2008 study by the NYSDEC. Chinese Mitten Crabs are the only freshwater crabs in North America, and they can be found at the first barrier of a freshwater tributary (NYSDEC, 2008). Sure enough, the NYSDEC found 24 molts of the crab at the bottom of Sparkill Creek dam in Piermont. This reinforces the idea that the dam may be preventing further alteration to the Sparkill Creek ecosystem. This is reassuring because it allows allows the restoration of The Sparkill Creek to become more manageable as the source in Clausland and the dam in Piermont limit the area where foreign species can be introduced. Despite this, a myriad of problems exist for the species of fish found in The Sparkill Creek. Their limited food sources may be contaminated with metals and their water likely contains other pollutants. Previous studies found a low diversity of fish, non-native fish and fish accustomed to stress. Dr. Rosko, an ecologist and professional on the Sparkill Creek discovered only 16 species of fish out of the 4,278 that were caught and identified in the creek in 1998. Of these 16 species, about half were resident indigenous while the rest were non-resident fish. Seven sunfish were found to be infected with a parasite during this study which may be related to weakened immunity due to environmental stressors.
The fish in the Sparkill Creek from the dam on upstream are all generalists. They are fish that are able to adapt to a wide variety of changes and stressors. White Suckers and Tesselated Darters are most common throughout the creek. Pumkinseed Sunfish, Blacknose Dace, and Mummichog were also found to be common. The lack of fish diversity and the presence of generalists, are the result of erosion, nutrient enrichment, contamination and the drastic habitat alteration occurring in the last two centuries. River Herring have been spotted close to the mouth of the creek, and their populations are currently in danger. There may be other rare fish that can be found between the mouth of the creek to the first dam, although additional data will need to be collected to verify this. Water chemistry variables such as pH, alkalinity, water temperature, and DO did not suggest that they were limiting factors. Although this is true, the DO levels may not still not be adequate to support certain larvae. Conductivity and turbidity were found to be outside of the acceptable parameters for supporting certain aquatic life. Furthermore, the 1998 study by Mr. Rosko found that a direct result of the sedimentation is the smothering of fish eggs. Nutrient enrichment is also believed to be an attributing factor in limiting the fish. As it causes the overgrowth of certain plants, sources of vital food may become limited and difficult to access. Despite the lack of diversity, there most certainly is a fish population in The Sparkill Creek.
Invasive Species
There are several invasive species that are destroying biodiversity not only along The Sparkill Creek, but throughout the County, the State and the country as well. The Mile a Minute Weed is an invasive plants that is mentioned in the Environmental Issues Section. It grows at a very high rate and has the ability to completely cover native tree and plant species. It can be found along the bank of The Sparkill Creek and may contribute to some of the erosion issues by damaging the plants with extensive root systems.
In the wetland areas along the creek, phragmites are the main invader. Purple Loosestrife and Flowering Rush are also common in local wetland areas. Although they give a marsh a "natural" appearance, they are actually extremely harmful. They all have the ability to dry wetland areas out, block sunlight, block migration and ruin habitats. They take over the habitats of native plants, and have the ability to interrupt all aspects of the ecosystem. As they destroy the food sources, a domino effect is scene throughout the food web. These three plants are the primary wetland invaders in New York. They are all very weak and fast growing with incredibly rapid reproductive capabilities. Ways to eradicate these invasive species are extremely limited and require well thought out strategies will long term maintenace plans.
Flooding
Although flooding is a natural phenomenon and floodplains line the creek, what occurs with The Sparkill Creek is most certainly not natural. This "supercharged" creek is highly reactive to rain due to a variety of factors. Over the years the watershed has gone from covered in trees to covered in pavement and buildings. Instead of leaves breaking the fall of rain droplets, rain now pummels lawns, gardens and dirt causing channels to form and sediments to migrate. It collects in gutters and runs toward sewers creating the ability for a lot of excess water to form in a very short amount of time. When the vegetation is lost, then the amount of water used by plants, the amount of surface area for water, the amounts of evaporation and evapotranspiration are all lessened. This substantially increases the volume of water that flows toward the creek. Furthermore, when impervious surfaces like parking lots drain directly into the creek, the time that it takes from the point the rainwater falls into the watershed to enter the creek is rapidly decreased, which fuels the high velocity of flow. Several man-made tributaries of The Sparkill Creek undoubtedly fuel flooding by displacing water from areas that would normally be flooded and directing the water into the Sparkill Creek. Metal culverts and cement drainage features frequently seen throughout the watershed make for the rapid displacement of water and those living adjacent to the creek bear the brunt of problems during times of high precipitation. Flooding in the lower Sparkill Creek area is not only agitated by the fact that there are tidal influences there, but also because it has the lowest surface elevation in the region.
Before a small storm After a small storm
Overall Water Quality
It would be expected that as the watershed of The Sparkill Creek goes from a forested area to highly developed area, the quality of the water would decline accordingly. The majority of the unnatural influences on the creek commence as the water exits the parkland. The 2003 NYSDEC Biological Assessment would verify this as it concluded that "water quality declined linearly downstream." The water flowing off of Clausland Mountain was concluded as being "good." while the water in Sparkill was "poor." This supports the idea that water coming off of Clausland Mountain is suitable for supporting a variety of aquatic life and that the impacts occur as the creek enters the developed areas of Orangetown. The overall water quality of The Sparkill Creek is difficult to assess due to the high degree of variation from the source to the mouth. As previous reports have stated, this is a moderately impacted body of water that has been damaged by anthropocentric influences.
Conclusion
Based on this environmental review it appears that with the proper nutrient enrichment controls and erosion controls, there is the potential for aquatic life to greatly improve and become more diverse. There also appears to be a tremendous potential for the overall recovery of The Sparkill Creek with respect to water quality. The overgrowth of algae can only be limited by the citizens and the municipality who introduce the nutrients into the creek. The restoration of aquatic life will support bird life both inland and in The Piermont Marsh. The potential for improved recreational activities certainly exists with such improvements.
Environmental Studies
2008 - Riverkeeper continues a long term sampling program in The Sparkill Creek. Results revealed elevated levels of Enterococcus, a sewage indicating bacterium. These levels are unacceptable for swimming by EPA standards and may cause health risk upon exposure. http://www.riverkeeper.org/special/swimmableriver/site.php?id=26-SC1
2007 - The Rockland County Drainage Agency sampled silt from The Ferdon Mill Pond section of The Sparkill Creek in Piermont, pollutants known as Unburnt Hydrocarbsons (UHC's) were found to be present. UHC's are associated with soot from automobile exhaust.
2004 - The New York Department of Environmental Conservation does a biological assessment on The Sparkill Creek. It found that there was a light to moderate impact, and water quality declined linearly downstream. Nutrient enrichment and organic waste from urban runoff was damaging fauna. Metals, PAH’s & Pesticides were found in invertebrates. http://www.nysl.nysed.gov/scandoclinks/ocm54759984.htm
The New York Department of Environmental Conservation also did a Water Classification study on The Sparkill Creek Drainage Basin. It found that the waters shall be suitable for fish, shellfish, and wildlife propagation and survival. http://www.dec.ny.gov/regs/4558.html#16954
2002 - The Hudson Basin River Watch performed a Modified Rapid Bioassessment. They concluded that the water quality was moderately impacted and that pollutants were entering the water system and adversely affecting its biological integrity. This was effecting its ability to sustain a healthy balanced population of native aquatic biota. http://www.hudsonbasin.org/Bioreports/Sparkill_02.pdf
1998 - John Rosko, an ecology professor at Saint Thomas Aquinas College, conducted a study on the fish populations in The Sparkill Creek with his students. They found that the elevated quantities of sediments from erosion were smothering fish eggs. They also found a low diversity of fish species and the presence of a parasite in the sunfish.
1993 - Hudsonia did a study and found that The Sparkill Creek was severely degraded due to erosion and siltation in the watershed, untreated stormwater runoff, removal of streamside vegetation and possible untreated sewage overflow. They reported mainly finding fish species that were pollution-tolerant and they suspected it had to do with runoff. They also found high concentrations of chloride, believed to be from road salt.
