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. 3. Physical Analyses Sediment samples were also classified by a soil engineering testing firm and grain size distribution performed on sediment from the four sampling locations. In-place cores of the top 20-inches of sediment as well as composites of sediment collected at depths between 0-4 feet were analyzed. The above analyses are contained in Appendix B. The surface cores are denoted as T-1, T-2, T-3, and T-4 as samples contained in tubes. The composite samples are denoted as B-1, B-2, B-3, and B-4 as samples contained in bags. The sediment samples varied in composition from approximately 30 to 90 percent sand and gravel and approximately 10 to 70 percent silt and clay. B. WATER QUALITY MONITORING 1. Suspended Solids and Phosphorus Monitoring • Water quality monitoring was conducted on the major inflows and the outflow from Lake Orono. Grab samples were collected a minimum of 18 times over a one year period from the Elk River at County Road 15 bridge (ERCR 15), Tibbits Brook at a point downstream from the County Road 35 bridge below County Ditch 28 (TBCR 35), and the outflow of Lake Orono at the dam. During the spring flooding period it was necessary to sample Tibbits Brook directly from the County Road 35 bridge (April 9th, 16th, and 23rd). See Figure 3 for the location of the monitoring stations. The sum of the drainage areas upstream of the two major inflow monitoring stations constitutes approximately 98 percent of the total Lake Orono drainage area of 388,000 acres (Figure 2). Total suspended solids .(TSS), total phosphorus, and ortho phosphorus were analyzed for each sampling event. Volatile suspended solids (VSS) were analyzed for the last eleven sampling events. Monitoring at the Elk River and Tibbits Brook stations was conducted by the Sherburne Soil and Water Conservation District by the following methodologies: grab samples were collected from the top one foot of water using a polyethylene gallon jug which had 41 N:\059EID I\ELKRI VER.RPT-NCW 4