The Spring River in southwestern Missouri and southeastern Kansas is a high-value aquatic resource with a history of poor water quality. This study of the Spring River basin provides a high frequency synoptic evaluation of water quality in the Spring River between Waco, Missouri and Riverton, Kansas below Empire Lake as impacted by five tributary streams (Cow, Center, Turkey, Center, and Shoal creeks). Total reactive phosphorus (TRP), total phosphorus (TP), nitrate-N, total ammonia-N, and discharge were estimated 26 times from January to November 2001. Evaluation of mean nutrient concentrations at base flow and runoff conditions indicated that most nutrients entering the Spring River from its tributaries were due to agricultural runoff. The primary exception to this trend was Turkey Creek, where some mean nutrient concentrations were significantly lower during runoff compared to base flow (P <0.05 for TRP, TP, and nitrate-N), suggesting a greater importance of point sources. Instantaneous nutrient loads were calculated for each site. The largest hydrologic load was associated with Shoal Creek (32% of total sub-basin loads), followed by the Spring River at Waco (28%), Center Creek (21%) and Turkey Creek (10%). Shoal Creek had the greatest P-load (42% of combined sub-basin loads for TRP and 39% of TP), followed by Turkey Creek (27% of TRP and 24% of TP) with only 10% of the hydrologic load. Nitrate loads were more equitable (29% from the Spring River at Waco, 28% from Shoal Creek, and 23% from Center), but the Spring River at Waco dominated total ammonia loads with 41% of the total sub-basin load. A comparison of combined sub-basin loads to the load estimated downstream suggests that Empire Lake is a sink for TP and TRP, and relatively neutral to the nitrogen parameters.