Effluent discharges have a profound effect on net phosphorus uptake in streams, where dissolved phosphorus usually travels kilometer scale distance before net retention,  This study evaluated the effect of a new effluent discharge on stream phosphorus concentrations and retention in the receiving stream, Goose Creek, and further downstream at the Illinois River in northwest Arkansas.  Water samples were collected before the municipal wastewater treatment plant started discharges and thereafter on an approximately every other week to monthly basis.  The new effluent discharge had an immediate impact on dissolved and total phosphorus concentrations in Goose Creek; this increase in phosphorus concentrations was almost immediately observed 10 kilometers further downstream in the Illinois River.  Goose Creek showed little intrinsic ability to retain dissolved phosphorus, suggesting that sediments within the fluvial channel have little phosphorus buffering capacity.  The observation that phosphorus concentration increased in the Illinois River less than a week after the effluent discharge began, suggest that this source will be important in watershed management planning and it may limit the ability of the Illinois River to retain dissolved phosphorus from other sources.