Population in 2000: The total number of individuals in 2000 as reported in the U.S. Census. Source:  U.S. Census Bureau, Census 2000 Summary File 1. Population Projected for 2020: The projected population in 2020 as utilized by the Texas Water Development Board for use in its 2002 State Water Plan. Projections are based upon a number of assumptions about both growth through continued births, as well as in and out-migration. Source:Texas Water Development Board, 2002 State Water Plan, "Population Projections by County."   Total Water Use 2000 Surface Water Use, 2000 Ground Water Use, 2000 Estimated total acre-feet, surface and ground water used for all purposes, including livestock watering, mining, power plants, manufacturing, irrigation and residential use in 2000.. Source:TWDB, 2000 County Historical Water Use, 2003 Per Capita Water Use 2000 The Per-Capita Water Use figure is based upon converting the total acre-feet of municipal use taken from the 2000 County Historical Water Use Database to gallons and then dividing by the population and then by 365 days. Source:TWDB, 2000 County Historical Water Use, 2003   Projected Total Water Use, 2020 (Acre-Feet): The water demand figures are based upon a number of assumptions about future water use in a particular county, developed in concert with the 16 regional water planning groups.. Source: TTWDB, 2002 State Water Plan, Regional Water Demand   Total Number of Active Surface Water Rights Permits, 2002: Total Authorized Volume of Water, 2002: These numbers show the total number of active state water rights permits authorized by the Texas Natural Resource Conservation Commission, as well as the total amount of water authorized for diversion per year, in acre-feet, of those water rights, as of 2002. The right to a certain volume of water is dependent upon water availability and is merely the maximum amount that could be used. Source:TTCEQ, Water Rights Database, 2002   Regional Water Planning Group: These letters indicate which regional planning group or groups the county belongs and links to pages with greater detail on water use in the group areas Source: Texas Natural Resource Information System (TNRIS).   Number of Real-Time Streamflow Monitors in the County: This number links to a list of real time streamflow monitors in the county which in turn to link into the USGS pages for each monitor. Source: United States Geological Survey