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IV. Conclusions <br /> 1. Sedimentation rates within Lake Orono appear to be in the range of 1,700 to 6,900 tons per <br /> year, equivalent to 0.004 to 0.017 feet per year over the whole lake area. <br /> 2. Sedimentation in Lake Orono consists of primarily the coarser bed load fraction of the Elk <br /> River's sediment load. There appears to be no net deposition of total suspended solids within <br /> Lake Orono. <br /> 3. Total phosphorus and total suspended solids concentrations in the Elk River are within the <br /> typical range for minimally impacted streams within the same part of the state. <br /> 4. Total phosphorus concentrations in Tibbits Brook are 25 percent higher than in the Elk River <br /> • and are on the high end of the typical range for minimally impacted streams within the same <br /> part of the state. <br /> 5. In-lake total phosphorus concentrations in Lake Orono are very high compared to minimally <br /> impacted lakes within the same part of the state. Based on total phosphorus data Lake Orono <br /> is classified as hypereutrophic. <br /> 6. Poor water quality in Lake Orono is largely due to a very high watershed drainage area to <br /> lake volume ratio, resulting in average water residence times of approximately three days. <br /> 7. Monitoring in the swimming area of the city beach indicated high levels of fecal coliform <br /> bacteria above national public health association guidelines. <br /> • <br /> N\05961ORELKRIVER.RPT-NCW <br /> 16 <br />