Reflections in the Susquehanna
Photo by Sylvia Kniss
The Hydrology of Middle Creek
by: Emma Dickinson & Alex Kauffman
INTRODUCTION
Middle Creek is a tributary of Penns Creek that eventually joins The Susquehanna River. It runs through Paxtonville, Middleburg, Kreamer, and Kantz in Snyder County, Pennsylvania. The creek was dammed east of Hidden Valley Road (40° 46 ‘00.5″N 76° 52’ 19.2″W) from 1833 until 1992 to provide energy to local citizens (Schnure, 1918). Using the known history of the stream as well as existing literature and sediment cores, the impact of the dam can be determined retroactively using hydrographs, a Hjulstrom curve, and photographs of the site. Middle Creek allows for an understanding of how human impacts have changed the region’s hydrology over time.
FINDINGS AND ANALYSIS
History of Musser Dam
Middle Creek was dammed from 1833 until 1992. The Hilbish Dam, a timber dam owned by the Hoover Water Company, served to power grist and sawmills. The Hoover family owned the land around the dam from 1874 until 1905 (HAER pa-220, n.d.). In 1906, the Hoover Water Company dam was replaced by a hydroelectric dam located on Middle Creek west of US-11 and North of state Game Lands 212, designed by engineers F.W. Darlington and E.F Shatzer (HAER pa-220, n.d.). In 1934, the Sunbury region experienced a major flood that destroyed the hydroelectric dam (Geological Survey Water-Supply, 1937). Reconstruction occurred two years later in 1936, which is likely when the fish ladder seen in post-1934 photographs was added (HAER pa-220, n.d.). The dam and surrounding property changed ownership many times but was referred to as “Musser Dam” after the site owner Mark Musser, who purchased it from the Pennsylvania Power and Light Company in 1954 (HAER pa-220, n.d.). Later, the Fish Commission purchased Musser Dam and stopped electricity production. In 1983, the facility was leased to a power plant and produced electricity up until it was decommissioned in 1992 due to safety concerns (HAER pa-220, n.d.).
IMPACT OF THE DAM
All the dams constructed on Middle Creek reduced streamflow and created Middle Creek Lake. In many cases, streams are dammed to form lakes because they retain water during storm events and release water downstream at a constant rate (Słowik, 2021). While this was not the historic intent of Musser Dam’s construction, it likely still served as flood control and regulated discharge during high precipitation events. The known service of reservoirs suggests that following dam construction, the hydrograph of Middle Creek would have a flatter appearance and a lower peak discharge (Figure 1).
Figure 1. The hydrographs depict the general changes in stream discharge following a precipitation event based on the presence or absence of a dam. The hydrograph of Middle Creek prior to Musser Dam shows a much higher peak discharge, which may correspond with a higher chance of flooding.
Sediment cores extracted across Middle Creek in the fall of 2023 revealed that finer sediments were deposited in the wider part of the lake compared to the narrower part of the lake. This observation was unexpected because finer sediments are usually more abundant closer to the site of dams and taper with distance (Edwards, 2006). The expected trend occurs because fine silts and clays require low-energy environments to fall out of suspension, and the lowest energy in the system is typically closest to the dam. However, the shape of Middle Creek Lake indicates the energy is lowest further from the dam (Figure 2), and most of the clay and finer particles would therefore be deposited closer to the location of core 2 as observed.
Figure 2. Middle Creek Lake 1938. This aerial photograph shows the widest portion of the lake, and thus the portion with the lowest energy is farthest from the location of the dam (PASDA, n.d.).
Implementation of a dam would have significantly reduced the water’s velocity during the shift from a stream to a lake environment. Reduction in flow velocity limited the competence of a stream, as well as its ability to carry a suspended load and bedload. Neither historic nor current water velocity data for this portion of Middle Creek is publicly available but based on the fine silts and clays found in the sediment cores, water movement in Middle Creek Lake must have been minimal. Using sediment cores and a Hjulstrom curve, the flow of water through the lake was estimated to be less than .4 cm/s (Figure 3).
Figure 3. The Hjulstrom curve shows the relationship between water velocity and grain sizes that can be eroded, transported, or deposited. Because silts (.0039-.0625mm) and clays (<.0039mm) were found in historic sediments deposited in Middle Creek Lake, movement of water would have to be at a velocity less than or equal to 0.4 cm/s to permit the observed deposition (Wentworth, 1922).
During storm events, the 1934 flood, and the removal of the dam in 1992, discharge and water velocity would be expected to rise substantially, increasing the competence of the stream. In general, Middle Creek Lake was a depositional environment.
Musser Dam created a mile-long lake, and when it was not experiencing turbulent flows from dramatic events, Middle Creek Lake probably contained the same ecological zones found in other lake environments. Old photographs (see figure 4) and articles by the Fish and Boat Commission identify Middle Creek Lake as an excellent fishing location, supporting the existence of a prolific littoral zone (Darlington et al., 1968).
Figure 4. Photograph of fishing in Middle Creek Lake, 1968.
Records of lake depth and temperature are not widely available; therefore, identifying the historic position of any thermocline is not possible. If the water body was too shallow and narrow, differentiation between the epilimnion and the hypolimnion layers may not have even been distinct at all.
ANALYSIS OF MODERN MIDDLE CREEK
After the removal of Middle Creek Dam, the physiology of the creek changed significantly. The high discharge from the dam removal caused sediment scour, which formed the new creek bed. As depicted in Figure 5, present-day Middle Creek runs through the southern edge of where the lake used to be.
Figure 5. Middle Creek Lake compared to the current creek path seen as the black line.
The specific location of the new creek bed may be a result of erosion near the thalweg, which typically is present along the outside of curves in a meandering stream (Cech, 2009).
After the lake drained and the stream reestablished natural flow, legacy sediments that accumulated behind these dams can now be studied. Sediment cores showed fine-grained material, but the new lakebed itself is composed of very coarse-grained substrate, evident of an increase in water velocity since the breach of the dam in 1992.
The exposed beds from the lake have been covered by the invasive Reed Canary Grass which has shallow roots that only hold onto the top layers of soil. This contributes to the high porosity of the sediment and can cause sections of the bed to easily erode, making the old lakebed of Middle Creek Lake unsuitable for most land uses. The land cannot be farmed due to the high water table and lack of any organic matter in the beds as observed in the sediment cores. It also cannot be used for building development because of the instability and impermeability of the sediments. Percolation tests for buildings would most likely fail due to the high saturation and clay material in the beds.
CONCLUSION
Middle Creek is an example of how human intervention impacts the hydrology of a region. Using historical documents, hydrographs, a Hjulstrom curve, sediment cores, and photographs of the site, trends can be identified and analyzed to form a general overview of the changes. When the first dam was built, water velocity and total discharge decreased dramatically. Based on the shape of the lake, energy was lowest on the western side of the lake. Middle Creek Lake was a depositional environment. Once the dam was breached, the water velocity and discharge increased and scoured out a new creek bed at the thalweg of the meandering curve.
Now, the creek bed is coarse-grained, and the old lakebed is exposed -populated by Reed Canary Grass. Ultimately, the consequence of the dam on Middle Creek is a strip of unusable, clay-rich sediment. Understanding how the implementation and removal of dams affected Middle Creek is crucial for making informed decisions about potential infrastructure or existing structures in waterways.
Works Cited
Cech, T.V., Wiley, J. (2009). Principles of Water Resources, 3rd Edition. ISBN# 9780470136317
Darlington, F. W., Shatzer, E. F., Reinberger, M., Eisenman, G. A. (1968). Middle Creek Hydroelectric Dam, On Middle Creek, west of U.S. Route 15, 3 miles south of Selinsgrove, Selinsgrove, Snyder County, PA. Historic American Engineering Record. Retrieved from the Library of Congress, https://www.loc.gov/item/pa2635/.
Edwards, R.E. (2006). Comprehensive Analysis of the Sediments Retained Behind Hydroelectric Dams of the Lower Susquehanna River. Susquehanna River Basin Commission, Publication 239. https://srbc.gov/our-work/reports-library/technical-reports/239- sediment-behind-dams-analysis/docs/sediment-behind-dams-analysis.pdf
Geological Survey Water-Supply (1937). The Floods of March 1936 Part 2. Hudson River to Susquehanna River Region. Paper 799, p. 236.
HAER pa-220. (n.d.). Historic American Engineering Record Middle Creek Hydroelectric Dam. https://tile.loc.gov/storage- services/master/pnp/habshaer/pa/pa2600/pa2635/data/pa2635data.pdf
PASDA Pennsylvania Imagery Navigator (n.d.). https://maps.psiee.psu.edu/imagerynavigator/ Schnure, W. M. (1918). A chronology of Selinsgrove, Pennsylvania 1700-1850 (from the
Middleburg Post), vol. 1, p. 114.
Słowik, M., Kiss, K., Czigány, S., Gradwohl-Valkay, A., Dezső, J., Halmai, Á., Marciniak, A., Tritt, R., and Pirkhoffer, E. (2021). The influence of changes in flow regime caused by dam closure on channel planform evolution: insights from flume
experiments. Environmental Earth Sciences 80, 165. https://doi.org/10.1007/s12665-021- 09437-5
Wentworth, C. K. (1922). A scale of grade and class terms for clastic sediments. The Journal of Geology 30(5): 377-392.