Imports data from USGS site file site. This function gets data from here: https://waterservices.usgs.gov/
Value
A data frame with at least the following columns:
| Name | Type | Description | 
| agency_cd | character | The NWIS code for the agency reporting the data | 
| site_no | character | The USGS site number | 
| station_nm | character | Site name | 
| site_tp_cd | character | Site type | 
| lat_va | numeric | DMS latitude | 
| long_va | numeric | DMS longitude | 
| dec_lat_va | numeric | Decimal latitude | 
| dec_long_va | numeric | Decimal longitude | 
| coord_meth_cd | character | Latitude-longitude method | 
| coord_acy_cd | character | Latitude-longitude accuracy | 
| coord_datum_cd | character | Latitude-longitude datum | 
| dec_coord_datum_cd | character | Decimal Latitude-longitude datum | 
| district_cd | character | District code | 
| state_cd | character | State code | 
| county_cd | character | County code | 
| country_cd | character | Country code | 
| land_net_ds | character | Land net location description | 
| map_nm | character | Name of location map | 
| map_scale_fc | character | Scale of location map | 
| alt_va | numeric | Altitude of Gage/land surface | 
| alt_meth_cd | character | Method altitude determined | 
| alt_acy_va | numeric | Altitude accuracy | 
| alt_datum_cd | character | Altitude datum | 
| huc_cd | character | Hydrologic unit code | 
| basin_cd | character | Drainage basin code | 
| topo_cd | character | Topographic setting code | 
| instruments_cd | character | Flags for instruments at site | 
| construction_dt | character | Date of first construction | 
| inventory_dt | character | Date site established or inventoried | 
| drain_area_va | numeric | Drainage area | 
| contrib_drain_area_va | numeric | Contributing drainage area | 
| tz_cd | character | Time Zone abbreviation | 
| local_time_fg | character | Site honors Daylight Savings Time | 
| reliability_cd | character | Data reliability code | 
| gw_file_cd | character | Data-other GW files | 
| nat_aqfr_cd | character | National aquifer code | 
| aqfr_cd | character | Local aquifer code | 
| aqfr_type_cd | character | Local aquifer type code | 
| well_depth_va | numeric | Well depth | 
| hole_depth_va | numeric | Hole depth | 
| depth_src_cd | character | Source of depth data | 
| project_no | character | Project number | 
There are also several useful attributes attached to the data frame:
| Name | Type | Description | 
| url | character | The url used to generate the data | 
| queryTime | POSIXct | The time the data was returned | 
| comment | character | Header comments from the RDB file | 
