Document Type

Technical Report

Publication Date

1-1-2011

Keywords

Phosphorus, Sediment, Reservoir, Oklahoma, Poteau Valley Improvement Authority

Abstract

A previous reservoir model of Lake Wister, Oklahoma suggested that internal P sources were dominant, and that a watershed management plan need not be developed to address external sources. The objectives of this study were to collect intact sediment cores from three sites at Lake Wister and measure sediment O₂ demand (SOD) and soluble reactive P (SRP) release to the overlying water during lab incubations under quiescent conditions. The measured SOD rates were between 9.9 and 22.6 mg m⁻² hr⁻¹ on average across the three sites, where the shallow headwaters site had the least SOD. The SRP release rates were estimated to vary from less than zero to 3.30 mg m⁻² d⁻¹ on average across the sites, and release rates were greatest under anaerobic conditions in the cores collected from deep waters near the dam and water intake structure. These measured values were an order of magnitude less than used in the calibration of the previous reservoir model, suggesting that internal P cycling was likely not the dominant P source; thus, it might be premature to neglect external P sources to Lake Wister. A watershed‐based strategy that focuses on internal and external P sources is needed for this drinking water supply reservoir to improve overall water quality.

Report Number

MSC364

Page

14

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