Pennsylvania is well regarded for its forest, but we are equally replete with waterways. Pennsylvania has over 85,000 miles of streams and waterways packed into just 45,000 square miles. This puts Pennsylvania squarely into the lead for highest stream density of any state. About 6% of Pennsylvania’s area consists of waterways or wetlands, an area twice the size of Rhode Island!
Streams and Waterways
Half of the state drains through the Susquehanna River and eventually into the Chesapeake Bay. This includes the area we live in. The remainder of the state is mostly broken between the Delaware and Ohio Rivers. A small number of other watersheds cross into Pennsylvania’s borders, but they represent a small fraction of our total drainage. From our home state you could catch a river network that could take you south to the Gulf of Mexico, east to the Atlantic Ocean, north to lake Ontario, or west to lake Erie. We sit rather uniquely in this regard as few other states have as many options downhill.
Major Watersheds of North America
Because we have had shockingly few mountain building events in the past 100 million years, our rivers have had great authority to really shape the land to their needs. Major surface waterways in our region have remained relatively unchanged since the last glacial maximum and even before then, as the glaciers never made it to the south end of Centre county. The many gaps in our ridges are the remnants of that ancient water’s exploitation of faults or cracks in the original mountains.
Much of our waterways’ direction and nature today come from the underlying geology. Areas of exceptionally hole-y rock, like many of our valley bottoms, absorb much of the rainfall only to spit it back out into the larger streams in timescales ranging from a couple of hours to decades. The types of rock the water flows through can also drastically alter the chemistry downstream. In Pennsylvania we typically classify streams as being limestone or freestone based upon that original geology. Freestone streams are more the classic river rock streams with water that can warm up drastically in the summer months and are usually fed by surface water or non-limestone springs. Limestone streams on the other hand are much colder-running as they are fed either by underground aquifers or ample spring flow that pass through limestone. Limestone streams offer better conditions for most aquatic life such as a more neutral pH and colder temperatures.
Rock alone is not the only measure of water quality, and humans have a tremendous impact on the quality of our waterways. Easy to recognize issues like sediments or pollutants that change the color of water drastically are often thought of first. A river after a large rainstorm, for example, is heavily affected by the quantity of sediments being washed downstream. Along with those sediments can be other unseen pollutants like fertilizers or other nutrients. These nutrients can cause toxic algal blooms, effectively killing everything else nearby when this occurs. These nutrients can also settle and increase the amount of plant life growing in calm areas ,strangling other types of life in the area.
What is often forgotten when thinking about water quality are temperature changes. The amount of oxygen water can carry is directly proportional to the temperature of the water. Water that regularly exceeds 70 degrees F will suffocate almost all cold-water animals from fish to insects leaving only warm-water species that are specifically adapted to less oxygen-rich environments.
When streams see an excess of these effects they can begin to be classified as impaired. This status is usually determined through data collected by scientists and is a qualitative measurement of the water quality. The water quality standards used to measure the health of a stream feed back into the strategies used to help recover the waterway. This can be as simple as adding stormwater management to allow sediments to settle before entering a stream, or as complex as establishing a total maximum daily load for a region to limit the amount of specific pollutants reaching the water.
Impaired Waterways in Pennsylvania
Adventurers looking to spend some time exploring waterways have a plethora of options awaiting them.
The Lower Trail is a 16-mile rail trail that follows along the Juniata river. Hikers, bikers, and most any other human-powered locomotion is allowed on the trail that starts a short distance from Canoe Creek State Park and ends near Alexandria. In addition to the river the trail also crosses a number of important birding areas as it meanders. There are several trailheads, referred to as stations, that allow visitors to select portions of the trip to explore without needing to traverse its entire length.
Millbrook Marsh offers fantastic views of several converging waterways. Bathgate spring offers a glimpse at a typical limestone-influenced tributary and nearby incorporates a man-made fen, another limestone feature essential to water quality. Visitors can also stroll around Slab Cabin Run before it joins with Spring Creek to see the difference in appearance between the two waterways first-hand.
Poe Paddy State Park is nestled by Penns Creek, a tremendous success story for water quality restoration projects. Pennsylvania Creek has gone from nearly a dead stream to having one of the highest measured fish biomass in the state. Visitors can explore the nearby tunnel that is part of the Mid State Trail and get a reprieve from a hot summer day as the tunnel is almost always a cool 55.
Visitors to Talleyrand Park can see the convergence of the Big Spring and Spring Creek. The water that flows out of the Big Spring has traveled dozens of miles through underground rivers before breaking to the surface in Bellefonte. This cold, and importantly very clean, water flows into the creek and acts as a buffer to any runoff associated with human development that flows into Spring Creek.