The availability of safe and adequate holding cover is a vital asset for the survival of many fish species. Trout in particular will utilize these cover positions for both their protection and the ability to ambush their prey. In high water conditions, the availability of such cover becomes exaggerated and are rapidly inhabited by the various trout species. During these periods of high water, it is also important to realize that the increased volume of water in a river system will transform the quality of certain structures that exist in otherwise normal conditions. For example, your favorite rock or log jam at low water is perhaps submerged with an increased flow rate, and is no longer providing an adequate current break that would typically hold fish. On the other hand, structures further up the bank may now provide optimal conditions in which a trout will hold. Structures such as fallen trees or large rocks are rather obvious to most fishermen, and will undoubtedly hold fish, but there are some other key, less obvious areas to pay close attention to as well.
Islands in most cases offer a plethora of favorable holding conditions from head to tail, and are not limited to high water levels. The areas at the beginning of an island, where the flow of water gets diverted into two separate channels can be great places to look. The deflection of current in these zones results in slower seems along the leading edges of an island, often creating perfect resting and feeding lanes for trout. Further current breaks will exist along the steep or grassy side edges of an island, also providing likely holding areas. Often times the most productive areas will be along the slack water edges at the tail end of an island where the current seems are typically softer. It is not uncommon to find fish cruising eddies in search of easy prey, but these areas can be difficult when attempting to present a fly, thus making the surrounding seems of an eddy easier areas to target.
As with islands, the banks of main river channels will offer adequate holding positions as well. Again, not limited to high water conditions, these areas can be great places to target trout if the proper cover is available. Other productive areas in both low and high water conditions include shallow riffles and the tail-outs of any pool. Although locating fish in these areas can be difficult at times, the increased current speeds do not allow the fish to carefully scrutinize your fly selection or your presentation. This causes fish to make less calculated decisions when feeding in these areas, often contributing to a fisherman's success and ability to sensationalize the fish stories shared amongst friends at the end of a good day on the water. As always, safety first! High water levels can easily create hazardous situations for those reluctant to exercise additional precautionary measures when fishing under such conditions.