WATER CHEMISTRY, WATER FLOW AND FISHERY MANAGEMENT ALONG BRIGHT ANGEL CREEK AND ITS TRIBUTARIES IN GRAND CANYON NATIONAL PARK

Bright Angel Creek (BAC) is a cool, high gradient, spring-fed tributary to the Colorado River in Grand Canyon National Park (GRCA). The native fish habitat in the GRCA has changed over time due to the introduction of non-native fish for sport fishing and the establishment of the Glen Canyon Dam. Native fish once flourished in the BAC but have diminished in recent years after non-native brown and rainbow trout were introduced. Three species of native fish are rare but present today in Bright Angel Creek: flannel mouth, bluehead sucker, and speckled dace. This study addresses changes in water flow and chemistry in the BAC and its tributaries. This information is important in regards to the current effort to reduce trout populations in BAC and reintroduce native fish. BAC has four main tributaries: Phantom, Ribbon, Wall, and Transept Creeks. Water data from these places can help determine if conditions will continue to support these native fishes or if conditions are more favorable for the non-native fishes. Our initial work consisted of looking for changes in basic water chemistry such as flow, temperature, pH, dissolved oxygen, oxidation-reduction potential, total dissolved solids, and specific conductance along BAC and its tributaries. Differences among their water flow and chemistry characteristics may suggest that fish populations would differ. Initial results suggest the tributaries vary among each other mainly in flow and hydrograph character. We have a higher concentration in total dissolved solids and specific conductance particularly in Transept Creek. We will address why these higher levels exist and their implications on fish habitat and population. Current water conditions in each tributary favor either native or non-native fish; these variables will determine the success rate of reintroduction of native fish.