TRAP EFFICIENCY AND SUSPENDED SEDIMENT LEVELS FOR OZARK MILL POND, OZARK, MO

The amount and distribution of sediment in a river system can adversely affect water quality. Excessive loading can cause the channel to alter its course and decrease the viability of the water as a natural resource. Suspended sediment levels for streams in the Ozark Plateau of Southwestern Missouri are not well understood and little data exists. The James River Total Maximum Daily Load (TMDL) states that high levels of suspended sediment are present but does not indicate where the source of the sediment is located. The tributaries of James River are the most likely source but sampling at the confluences does not support the level of suspended sediments found. The Finley River, a tributary of the James River, is part of the river system that feeds Table Rock Lake. According to the Finley River Watershed Management Plan, active bank erosion and excessive sedimentation are key problems but monitoring by the USGS gage site at the confluence with the James River indicates a lower amount of sediment than would be expected. This study will focus on the Ozark Mill Pond impoundment in Ozark, Missouri which is located on the Finley River. The purpose of this study is to determine the impact of impoundments on sediment retention and determine if the fine-grained sediment is flushed out as a pulse during storm events. Historical aerial photographs show the channel planform has changed little over the past eighty years indicating the sediment is either stored in the channel or deposited on the floodplain. The physical characteristics of the impoundment are found by creating bathymetric maps using field data that show the bedrock configuration and sediment accumulation. Total suspended sediment between 1.5µm and .45µm will be monitored to determine the amount of sediment that is flowing into and out of the impoundment. Trap efficiency calculations and field observations will be used to create a sediment budget. This study will assist local water managers in understanding stream sediment dynamics that can be used to address water quality problems.