| Preliminary Phosphorus Budget For Lake of the Woods | | Print | |
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A Report from Kathryn Hargan, Trent University The preliminary phosphorus budget for the Lake of the Woods (LoW) was presented at the 2009 International Lake of the Woods Water forum. The purpose of this research is to quantify all sources of phosphorus to, and losses from, the lake. These data will be applied to lake water quality models to predict current and future lake phosphorus concentrations and water quality conditions (e.g., chlorophyll, as a measure of algae, and oxygen levels) for a variety of management scenarios. The goal of the budget is to understand the contribution of natural and human-caused sources of phosphorus to the lake and the sensitivity of the lake water quality to increases in phosphorus inputs.Preliminary estimates indicate that the largest source of phosphorus to LoW is the Rainy River, contributing about 55% of the total phosphorus to the lake. Because of the importance of the Rainy River and the "local basin" identified in my preliminary results, a tributary monitoring program will begin this spring for the major streams flowing into both the Rainy River and the Lake of the Woods "local basin". It is important to note that the total phosphorus budget is preliminary. It will continue to be refined as more phosphorus samples are gathered and other relevant basin data are collected. For example, the amount of shoreline development around the lake is currently only crudely estimated but will be determined precisely as part of my research. Also, the preliminary phosphorus contribution to LoW from the "local basin" was estimated by extrapolating phosphorus export data measured for other lakes in North America. The initiation of a Lake of the Woods Tributary Monitoring Program this spring will provide a better estimate of the phosphorus contribution from the "local basin". In the coming year my work will focus on more detailed estimation of flows and phosphorus loads from tributaries to LoW and the Rainy River, as well as estimating total phosphorus budgets and developing water quality modeling for three isolated bays in northern Lake of the Woods. |