Oxygen Budget for Lake Ogallala

Authors

Kyle D. Hoagland, University of Nebraska-LincolnFollow
John C. Holz, University of Nebraska-Lincoln
Tadd M. Barrow, University of Nebraska-Lincoln
Richard J. Ruane

Date of this Version

2000

Citation

Hoagland, K.D., Holz, J.C., Barrow, T.M., Ruane, R.J. Nebraska Game and Parks Commission. 2000. Oxygen Budget for Lake Ogallala. (179 pp)

Comments

OFR-200

Prepared for Nebraska Game and Parks Commission

Abstract

Lake Ogallala, located below Kingsley Dam which impounds Lake McConaughy in Keith County, Nebraska, is a 260-surface hectare lake with an average depth of approximately eight meters. The lake provides mUltiple uses including a sport fishery and a hydropower and irrigation regulation basin. Since the installation of the hydroelectric generating plant in 1984 (Kingsley Dam was constructed in 1942) and the continued eutrophication of Lake McConaughy, dissolved oxygen concentrations have generally declined in Lake Ogallala. Hypolimnetic withdrawal from Lake McConaughy results in depressed oxygen levels in Lake Ogallala during the mid to latter part of the summer, particularly in certain parts of the lake. Thus, the Nebraska Game and Parks Commission, Nebraska Department of Environmental Quality, Nebraska Public Power District and Central Nebraska Public Power and Irrigation District have sought to devise a compatible management plan to facilitate all major uses of the lake and to comply with site specific dissolved oxygen criteria.

Development of a management plan for Lake Ogallala requires a sufficiently detailed knowledge of water flow dynamics in this complex system, as well as an understanding of the major sources and sinks of dissolved oxygen in the lake, paJiicularly late in the summer when dead fish have been found in the east arm of the lake. In conjunction with a project supported by the NGPC entitled, "Development of a Dissolved Oxygen Circulation Model for Lake Ogallala" (results not presented here), the proposed project was designed to provide sufficient data to construct a dissolved oxygen budget for the lake to be used to assist in accurately predicting the effects of various water release and aeration regimes in a spatially explicit manner. The overall aim of the two studies combined has been to provide a clear understanding of water mass and dissolved oxygen circulation dynamics in Lake Ogallala under the current management scenario, to facilitate knowledge-based decisions on optimal management alternatives.

The specific objectives of this project were to: (1) create a comprehensive model for the dissolved oxygen (DO) budget in Lake Ogallala, identifying the major sources and sinks, particularly during the critical late summer period; (2) integrate the DO and circulation models to create a dynamic, time-series model for the lake (integrating the models will allow us to predict temporal changes in the DO regime and create scenarios for other times during the year), and; (3) provide management recommendations based on the above findings and model projections.

The results presented here are based primarily on data collected in August 2000 by a team of 40 scientists, with representatives from Nebraska Game and Parks Commission, Nebraska Public Power and Irrigation District, Central Nebraska Public Power and Irrigation District, Nebraska Department of Environmental Quality, and the University of Nebraska (UNL and UNO). The data summary and analysis were performed by Reservoir Environmental Management, the primary consultant on this project. The results of the modeling component of the project will be presented in Part II of the final report, under the direction of co-PIs John Stansbury and David Admiraal (University of Nebraska, Department of Civil Engineering).