Cover page need figure & title by Proposed Table of Contents

Watershed information/delineation

Ground water

Groundwater is water that is found below the surface of the earth^lxi. It is contained either in unconsolidated or consolidated sediments (rocks)^lxii. Unconsolidated sediments are composed of loose grains (particles) and groundwater can be stored in the pore spaces of these grains^lxiii. In consolidated sediments (rocks), there are very few pore spaces between the grains, so groundwater is typically stored in openings between rock layers and in fractures^lxiv. The total amount of pore space in a rock or unconsolidated sediments is galled porosity^lxv. Unconsolidated sediments are typically able to store more water than consolidated sediments, with the exception of limestone and dolostone units (karst)^lxvi. These karstic rocks are easily dissolved and can often form caves; this allows for the storage of much more groundwater than in typical consolidated sediments^lxvii. While the majority of the groundwater storing units in the Raystown watershed are consolidated sediments, there are a fair amount of karstic units that are able to hold a lot of groundwater within this region. Figure of Raystown watershed with limestone/dolostone units in one color and other units in another color.

Groundwater also flows through rock units in which it is contained^lxviii. The main force causing groundwater to flow is the same force that causes surface water to flow: gravity^lxix. Groundwater will always flow downward from recharge areas on hills to discharge areas in valleys^lxx. The ease with which groundwater flows through rock or sediment is called permeability^lxxi. Permeability depends on the size of the pores, fractures, or openings and the degree to which they are interconnected^lxxii. Figure with flow path of water particle from infiltration to intersection w/ with water table, to interflow, to intersection w/ surface.

Aquifers

Groundwater does not flow through all rocks because some rocks are much less permeable than others^lxxiii. Aquifers are the units of rock or sediment in which there is considerable permeability and groundwater flows from these units at are able to provide water for your home^lxxiv. There are two types of aquifers: confined and unconfined. Confined aquifers are overlain by a unit of low permeability (confining layer)^lxxv. Confining layers do still experience some groundwater flow, but is significantly less than the flow through an aquifer^lxxvi. Unconfined aquifers have no confining layer above them restricting flow^lxxvii. The pressure in some confined aquifers will cause water to readily flow from wells without the aid of pumping^lxxviii. These wells are considered artesian^lxxix. Figure showing a confined and unconfined aquifer, with an artesian well at the confined aquifer.

Every other year, the Hydrogeology class visits the Grove Farm Fieldstation and performs a pump test to determine the kind of aquifer that supplies the station with its water. *Include information on what is needed for the test, how it is run, and how to analyze the results, a map of the area, and past data and results from the test*

Surface water

In the water resources section we will look at a number of hydrological topics. These topics include surface water, groundwater, water usage, and water quality. All of the water resources in this section lie within the region of the Raystown Branch Juniata River watershed, which contains the Raystown Lake reservoir. In order to fully understand these water resources, it is important to get a general idea of the characteristics of the Raystown Branch Juniata River watershed. Figure 1.1 illustrates the span of this watershed, which falls just below the city of Huntingdon, Pa. and encompasses Saxton, Pa., Everett, Pa., Bedford, Pa., and Roxbury, Pa., with an approximate length of 57 miles and a maximum width of around 35 miles.³⁹ The major surface water present within this watershed is the Raystown Branch of the Juniata River. The Raystown Branch Juniata River drainage basin consists of an area of 960 square miles, which outlines the watershed boundary that lays within Huntingdon, Pa., Bedford, Pa., and Fulton Counties, Pa.⁴⁰ The Raystown Lake reservoir makes up a significant portion of the Raystown Branch and therefore has an equal significance to the Raystown Branch Juniata River watershed as well. The water resources related to this reservoir are of particular importance to the subject of this field guide and will be elaborated on further throughout the following sections.

Now that we have a better understanding of the characteristics of the Raystown Branch Juniata River watershed we can move on to describe the hydrological topics that are relevant to the region. The first topic that will be addressed is that of surface water, since it corresponds exclusively to the distribution of water throughout the watershed. If you refer to figure 1.1 on the adjacent page you can follow the flow of water traveling throughout the Raystown Branch Juniata River watershed. To begin this journey we will start at the western end of the watershed just above Roxbury at the location in which the Raystown Branch enters the watershed boundary. From this point it flows in an easterly direction for about 48 miles, past Bedford, Pa. and Everett, Pa., where it comes to a sharp bend and then travels in northerly direction past Saxton, Pa.⁴¹ Further downstream from Saxton, Pa. the Raystown Branch becomes a part of the Raystown Lake reservoir, which extends for 34 miles upstream to the location of the dam.⁴² From the point of the northern ascension on the Raystown Branch the river travels a distance of about 76 miles before it joins up with the Juniata River.⁴³ The dam on the Raystown Branch is located 5.5 miles upstream from the confluence with the Juniata River, below Huntingdon, Pa.⁴⁴ The position of the dam signifies the end of the Raystown Lake and the end of the Raystown Branch Juniata River watershed. The purpose of the dam was to back up flow to form Raystown Lake with the designed intention to supply the surrounding region with flood control, recreation, and water quality of outflowing water.⁴⁵ The lake contains a recreational pool at an elevation of 786 feet above the mean sea level, with an area of 8,300 acres, extending 30 miles upstream.⁴⁶ The flood control pool at the lake has an elevation of 786 feet above the mean sea level, with a surface area of 10,800 acres, extending 34 miles upstream.⁴⁷ The Raystown Branch Juniata River at Saxton has a drainage area of 756 square miles, 79% of this drainage area is controlled by the dam.⁴⁸

By referring to the graph in figure 1.2 we can observe the fluctuations in the elevation of the reservoir that occurred annually within Raystown Lake at a point below the Dam. The two spikes on the graph reflect historical floods that occurred within approximately the last 50 years. The first flooding event was caused by hurricane Anges in 1972, occurring just before the current dam was fully completed. In relation to this event one can see that after the completion of the dam by 1974, the dam was put to use and tested out resulting in high levels of release and low mean streamflow levels. The annual mean streamflow in cubic feet went from 2,156 in 1972 to 489 in 1974, so it is clear that the operators of the dam were testing the capabilities of the newly constructed dam and flood control system. The other significant flood event illustrated on the graph occurred during the winter of 1996 in which heavy snow falls led to high levels of thaw that in turn created flood conditions greater than that of this created by hurricane Anges in 1972. These high levels of snow thaw accumulated 2,266 cubic feet of water within the reservoir. The effects of the dam can be further observed through the interpretation of the graph in Figure 1.3, which depicts the annual streamflow averages for the Raystown Branch near Saxton. The location of this point is found downstream from the dam near the mouth of the Raystown Lake. This graph shows a distinctive resemblance to that of the graph in figure 1.2, because it reflects the effect of the dam on the Raytown Branch. Therefore, the characteristics of major surface waters in the region mainly the Raystown Branch should now be relatively understood from a hydrological point of view.

Not fully completed