The U.S. Geological Survey (USGS) has measured rainfall at various locations in Mecklenburg County, North Carolina, since 1963. Between 1992 and 1997, the USGS, in cooperation with Charlotte Stormwater Services, installed 43 raingages throughout Mecklenburg County and adjoining counties (fig. 1). These 43 raingages, combined with three previously installed gages, compose a data-collection network that provides detailed, accurate information on rainfall throughout the county. The Rainfall NetworkThe rainfall network consists of 46 raingages. Forty-one of the gages are located within Mecklenburg County, and five gages are located just outside the county line. These raingages are located in 37 named stream basins in the county, including all of the major stream basins in Charlotte and Mecklenburg County. Rainfall is measured to the nearest 0.01 inch at 5-minute intervals.

Multiply inch (in.) foot (ft) square mile (mi2) pint (pt) inch per year (in/yr) By 25.4 0.3048 2.59 0.4732 25.4 To obtain millimeter meter square kilometer liter millimeter per year Sea level: In this report "sea level" refers to the National Geodetic Vertical Datum of 1929 (NGVD of 1929) A geodetic datum derived from a general adjustment of the first-order level nets of both the United States and Canada, formerly called Sea Level Datum of 1929. Specific conductance is given in microsiemens per centimeter at 25 dgrees Celsius (|iS/cm at 25 °C).

Precipitation and hydrologic data were collected at 28 precipitation sites and stream sites in the city of Charlotte and Mecklenburg County from October 1993 through June 1995 to identify the type, concentration, and amount of nonpoint-source stormwater runoff within the area. The data collected include measurements of precipitation; streamflow; physical characteristics, such as water temperature, pH, specific conductance, biochemical oxygen demand, oil and grease, and suspended sediment concentrations; and concentrations of nutrients, metals and minor constituents, and organic compounds. These data should provide valuable information needed for (1) planned watershed simulation models, (2) early warning of possible flooding, (3) estimates of nonpoint-source constituent loadings to the Catawba River, and (4) characterization of water quality in relation to basin conditions. Purpose and Scope The purpose of this report is to summarize the precipitation and hydrologic data collected in Charlotte and Mecklenburg County from October 1993 through June 1995. The data collected include measurements of precipitation; streamflow; physical characteristics, such as water temperature, pH, specific conductance, biochemical oxygen demand, oil and grease, and suspended sediment concentrations; and concentrations of nutrients, metals and minor Abstract 1 constituents, and organic compounds. This report also describes the field and laboratory methods used to collect and analyze these data. The data-collection network that was initiated in October 1993 with the City of Charlotte and Mecklenburg County consists of precipitation sites and 8 stream sites, which are needed to determine the effects of land development on water quality and to evaluate the effectiveness of control measures (fig. 1). Six of the sites define runoff characteristics from streams with differing land-use characteristics within the city, and two of the sites define runoff characteristics from streams located within the county. These data should provide valuable information needed for stormwater management, estimates of nonpointsource constituent loadings to the Catawba River, and information needed to calibrate watershed models necessary for evaluating stormwater management options. Study Area and Sites Mecklenburg County is located in south-central North Carolina within the southern Piedmont Province and covers an area of 528 square miles. The county is bounded on the west by the Catawba River and its reservoirs, Lake Norman, Mountain Island Lake, and Lake Wylie (fig. 1). The Catawba River drains approximately 75 percent of the county. The remaining 25 percent is drained by the Rocky River and its tributaries in the Pee Dee River Basin (McCachren, 1980). Lake Norman is the major watersupply reservoir for several municipalities in northern Mecklenburg County. Mountain Island Lake supplies Charlotte and several other municipalities in Mecklenburg and surrounding counties. Charlotte is the principal municipality in Mecklenburg County and the largest city in North ...

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