An intensive study of nonpoint-source runoff was conducted in the Twin Cities metropolitan area in Minnesota during 1980. The purpose of the study was to determine the relationships between land use, watershed characteristics, and the quantity, quality, and timing of runoff.
Discharge and water-quality data were collected at 19 sites located in 6 rural and 4 urban watersheds. Basin characteristics and land use were determined for each watershed. Recording instruments provided continuous discharge records at 17 sites and continuous rainfall records at 12 sites. Automatic samplers were used at 12 sites. Water-quality samples were collected at 15- to 60-minute intervals during periods of increased runoff. Samples were collected periodically during low flow. Primary emphasis was placed on analysis of samples for suspended solids, nutrients, and oxygen-demanding constituents. Secondary emphasis was placed on analysis for chloride, metals, bacteria, pesticides, and PCB's. Wetfall and dryfall precipitation-quality data were collected at six sites.
Discharge and water-quality data were used to calculate storm and daily loads of chemical oxygen demand, total suspended solids, ammonia plus organic nitrogen, nitrite plus nitrate-nitrogen, total phosphorus, chloride, and lead.
All data collected during the study are documented in tables that contain watershed characteristics and land use, daily and unit values for discharge and rainfall, rainfall characteristics, water-quality data for runoff and precipitation, results of laboratory settling tests, results of quality-assurance tests, dally loads, and storm loads.
