New & Noteworthy

 Ground-Water Availability in the United States (Circular 1323)

 CFP: Conduit Flow Process for MODFLOW-2005

 GSFLOW: A New Model for Simulation of Ground-Water and Surface-Water Interaction

 SEAWAT v4: Simulation of 3D Variable-Density Ground-Water Flow and Transport

USGS in Your State

USGS Water Science Centers are located in each state.

Guidelines for Index Well Selection for the CBR Program

In 1995, the Office of Ground Water began oversight of the ground-water Collection of Basic Record (CBR) Program. A description of the process used to select the initial CBR-funded wells can be found at CBR Program History. In FY2002, public web pages were announced that highlight the CBR wells. In later releases of the web pages, the Climate Response Network was enhanced to include non-CBR wells that met the same criteria. In FY2003, the CBR Program was rolled into the Ground Water Resources Program as a part of the overall USGS budget re-structuring.

Guidelines for Well Selection

These guidelines are to assist in identifying potential index wells to be part of a national, long-term water-level monitoring network. The end product should be a network of index wells where uninterrupted, long-term water-level records are collected. The water-level changes should primarily reflect climatic variability and not human influences. The climate variations of interest are those that affect recharge on monthly and longer time scales; not barometric or tidal influences.

Areas where water-level changes are relatively unaffected by human activity should be delineated on maps of the major aquifers in the District. Maps from the National Ground Water Atlas should be used in order to maintain regional continuity. Observation wells should satisfy the following required minimum criteria:

• Open to a single, known hydrogeologic unit
• Known well construction that allows good water-level measurements
• Located in unconfined aquifers or near-surface confined aquifers that respond to climatic fluctuations
• Minimally affected by pumpage and likely to remain so
• Essentially unaffected by irrigation, canals, and other potential sources of artificial recharge
• Long-term accessibility
• Well has never gone dry (not susceptible to going dry)

Additional desired characteristics:

• Representative of broad area (e.g., a regional aquifer)
• Complete characterization of the site is available
• A long record of water-level measurements exists
• Lithologic and geophysical logs available
• Alternative well identified for each site

Climate Response Network

All CBR network well data are served via the Internet from the Climate Response Network (CRN) web site. Districts are strongly encouraged to include non-CBR wells on the CRN web site if these wells meet CBR criteria. Additional wells can be added by submitting a list of site numbers to Linda Geiger. These wells must be configured using NW_edit, pushing all daily values data for the site to NWISWeb, and, entering tapedowns in GWSI prior to inclusion in CRN. Only approved daily values data are used to compute the statistics so timely approval of data is important.