The previous article in this three-part series discussed the recreational opportunities available at the Lehigh River and the struggling wild trout fishery that is present on the river today. Whitewater enthusiasts, nature lovers, anglers and our local governments have a tremendous opportunity lying in wait.

Recreation and tourism is one of Pennsylvania's leading industries. Whitewater rafting, kayaking, hiking, biking and trout fishing all surround the river. However, one aspect still struggles – the trout fishery. The management and current operation of Francis E. Walter Reservoir have a tremendous impact on the Lehigh River's trout fishery, to the point that they are largely accountable for limiting trout populations in the river.

Every summer, water leaving the F.E.W. Dam reaches temperatures that are not favorable for trout survival. Trout need water less than 68 °F to feel comfortable, to feed and to grow. Temperatures greater than 68 °F cause the trout to become stressed and they begin to seek colder water. During these times, trout become susceptible to disease and predation, both human and natural. When the lake behind the F.E.W. Dam loses all its cold water and begins discharging at temperatures of 70 °F or higher during the summer, this sends the trout into panic mode.

The manner in which the water is discharged from the reservoir is the leading contributor to this problem. The Army Corps of Engineers is handicapped and cannot regulate water temperatures being discharged from the dam. Water can only be released from the deepest part of the lake; therefore, only the coldest water is released all the time, even when it's not needed. As a result of this single option, the cold water in the lake is depleted by mid-summer. Once the cold water is gone from the lake, it isn't replenished until fall when inflow water temperatures decrease, or during spring when snowmelt turns our streams icy cold.

However, changes have been set in motion in an attempt to improve not only the trout fishery and the aquatic ecosystem, but whitewater rafting opportunities as well. The Army Corps, in cooperation with the PA Department of Conservation Natural Resources and the PA Fish and Boat Commission, are in the process of performing a temperature and flow model study, known as the "Coldwater Study", on F.E.W. and the Lehigh River.

This Coldwater Study will look at ways to keep the cold water in the lake, so that the coldest water can be discharged during the warmer summer months when it is needed most.

The study will investigate how a release of colder water from F.E.W. will affect river water temperatures at pre-determined downstream points. Simulations will be produced to show how river water temperatures are affected by releases of colder water.

The Coldwater Study will also look at improving whitewater releases and increasing water volume in the river during non-whitewater release periods. Increasing the flow during summer months will help improve water quality by reducing the impact of sewage and acid mine drainage that still affect the river.

But the most significant capability of the Coldwater Study will be its ability to simulate a discharge tower that is able to regulate water release temperatures. This should enable the Corps to analyze the effects of increasing the volume of water stored in the lake and suggest ways to sustain the cold water in the lake.

The best way to regulate water temperatures is to have the capability to discharge water from different lake depths. Water temperature gets colder with greater depth in a lake. Having discharge options at specific levels in a lake will allow the dam operators to regulate water temperature in the river below and retain the coldest water for longer periods of time.

Part III will look at the specifics of the ongoing Coldwater Study and how they will affect recreation, the aquatic resource, the trout fishery, and future possibilities.

Dean Druckenmiller