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r.nFI~1 I, HI, l' ~ During the data-collection period, activities in the basin affecting water Quality included sanding of streets during snowstorms, street sweeping, and con- struction. The city of Northglenn occasionally applies sand containing as much as ]-percent salt to streets during snowstorms, sweeps major treets weekly, and sweeps re5idential streets at least once a month. During the study. street sweep- ings were placed in a landfill near the confluence of Grange Hall Creek and the unnamed southern tributary (fig. 2). Construction during the study included resi- dential dwellings. commercial buildings, street and sewer improvements along l04th Avenue, and installation of a culvert on Grange Hall Creek at Grant Drive. Activ- ities of this type probably will continue to affect water quality in the basin for many years. DATA COLLECTION The location of equipment installed to collect data is shovm on figure 2. A detailed description of this equipment is given by Smoot, Davidian, and Billings (1974). Description of data-collection sites and the types of data collected at each site are listed in table 1. Ra i nfall Two types of rain gages--tipping-bucket gages at sites 2. 5, 6, and 8, and a float-type storage gage at site 7 (fig. 2; table I)--were used. The tipping- bucket rain gages were time-synchronized with the streamflow gages and automatic- sample collectors. Only a limited amount of rainfall data was collected at sites 6 and 8. PrecipitiHion data were not collected during the winter months. Estimated daily rainfall for 1978 and 1979 is given for site 7 in tables 3 and 4 (Hydrologic Data section at back of report). Cumulative rainfall for selected storms at sites 2, 5, 6, 7. and 8 is given along with the instantaneous streamflow in tables 5 through 21 (Hydrologic Data section. at back of report). Rainfall- runoff data for site 7 have been published by Cochran, Hodges, Livingston, and Jarrett (1979). Streamflow Continuous records of streamflow were obtained at sites 2 and 5 (fig, 2; table 1). A V-notch weir was installed at site 2, and a trapezoidal flume (Bu- chanan and Somers. 1969) was installed at site 5, Stage-discharge relationships were derived, using weir (King and Brater, 1963), culvert (Bodhaine, 1968), and step-backwater (Bailey and Ray, 1966) methods. supplemented with current-meter measurements. Mean dai ly discharges for December 1977 through September 1979 are given in tables 22 and 23 (Hydrologic Data section at back of report). Instan- taneous streamflow at one or both si tes and cumulative rainfall for selected rainstorms are given in tables 5 through 21 (Hydrologic Data section. at back of report). 5