Hopkins and Anderson report that the purpose of the TWDB’s water-level program is to gain representative information about static water levels in aquifers (water levels unaffected by recent or nearby pumping) throughout the state in order to support water planning from the local to a more regional perspective. The TWDB and its cooperators, primarily groundwater conservation districts (districts) and the U.S. Geological Survey (USGS), have been measuring depth-to-water at least annually in over 7,000 wells for the last two decades. It is not uncommon for districts to provide measurements more frequently than once a year when they start measuring wells in their jurisdiction that were previously measured by the TWDB.
Texas does not have an official “dedicated” network of wells that were drilled specifically as monitor wells. Instead, TWDB relies on access to privately owned wells, preferably that are no longer in service and not equipped. Fortunately, nearly half of the wells that the TWDB and cooperators measure are in this category; however, other wells that are part of the current observation (water-level) network are still in use and provide water for domestic, stock, irrigation, industrial, and public-supply.
Monitoring Section employees normally measure water levels during cooler months when groundwater pumping is at a minimum to ensure that measurements are most indicative of static or ambient conditions, particularly in those wells that are still in use. They also communicate with well owners in advance to be certain that pumps are turned off for at least 24 hours. The TWDB and other entities measure the same wells each year, recognizing the value of many measurements over as long a period of time as possible in the same location. TWDB and district employees strive to find replacement sites when access to a well is no longer granted (rarely) or when a well is destroyed or other conditions in the well bore preclude obtaining accurate measurements.
Whereas levels collected for the water-level program typically provide an understanding of water-level changes (or lack of) over a long period of time, water levels collected and posted online in the TWDB’s Recorder Program (unused wells equipped with automatic water-level recording equipment) provide current information and more frequent measurements (hourly) that allow cities and groundwater conservation districts to react quickly in mandating pumping limits during drought. The recorders measure water levels in (near) real time and transmit the data by satellite to the TWDB where daily readings of hourly measurements are published on the Water Data for Texas website. The equipment at each recorder well site typically consists of data loggers attached to water-level recording devices, such as transducers or floats and pulleys; satellite transmitters; power sources, including solar panels; antennae; and equipment shelters.
The number of groundwater conservation districts that work with the TWDB, typically through TWDB Groundwater-level Measuring Manual Page 4 of 22 purchase of equipment, to install more recorders that also provide data for publication on the TWDB Web site has continued to increase in the last decade. More than 10 groundwater conservation districts cooperate with the TWDB. While this cooperation is beneficial to both the TWDB and the local districts, staff limitations at the TWDB currently limit the number of recorders that can be maintained adequately at no more than 200 sites.
Although the two water-level data-collection programs are distinct, Monitoring Section employees working in the water-level program also visit recorders. They measure depth-to-water in all recorders at least once a year to check the accuracy of the data provided by the recorder equipment. All data collected by the TWDB Groundwater Monitoring Section and from cooperators that send in data on their monitored wells are available from the Groundwater Database (GWDB) Reports website.
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