Purpose: The purpose of the study was to (1) determine quantity and quality of urban runoff from the upper Grange Hall Creek drainage basin in Northglenn; (2) identify constituents exceeding water-quality standards for agricultural waters; (3) compare differences in quality between dry-weather flow, snowmelt runoff and rainfall runoff; (4) determine rainfall-runoff relationships; (5) investigate relationships between constituent concentrations, specific conductance, and streamflow; and (6) suggest, where appropriate, alternatives of urban-runoff management.