New Mexico
Environment Department

Contact Information:
(505) 827-2855 MAIN // 1-800-219-6157 (toll free)
Environmental Emergencies:
505-827-9329 (24 hrs)

Ground Water Quality Bureau

Monitoring Well FAQs

Q. Why do I need to install monitoring well(s)?

A. Regular sampling of ground water collected from monitoring wells is one way that NMED determines whether or not your discharge is affecting ground water quality… other words; whether or not your permit is working as intended.

Q. What is the difference between a water supply well and a monitoring well?

A. A monitoring well is a well that is used to sample water at the top of the water table, since that is where contamination that reaches groundwater will show up first. They are used for routine water quality monitoring, not water supply. Water supply wells are usually drilled much deeper and have longer screens in order to produce greater quantities of water.

Q. Can I use my water supply well as a monitoring well?

A. Generally, no. Monitoring wells are constructed and located specifically to detect ground water quality impacts early on, before a contaminant plume spreads. If you were relying on your water supply well for this purpose, by the time a problem is detected, the contamination could be much harder to address.

Q. Do you have a list of drillers?

A. NMED maintains a list of monitoring well drilling companies. This list is not all inclusive and does not constitute endorsement of these companies by NMED. If you are interested in having your company listed on this page, please contact Lochlin Farrell .

Q. What information do I provide to the monitoring well installer?

A. Provide the following:
•The monitoring well construction requirements can be viewed here.
•The well driller will need to contact the Office of the State Engineer about monitoring well permitting in your area.
•The well driller should use a dry drilling method to determine where the water table is.
•The well driller will need to prepare construction and lithologic logs for you to submit to NMED when the well is completed.
•The monitoring well should be labeled with an indelible mark so that it can be tracked under your Discharge Permit.

Q. Why is the survey and map of ground water flow direction and gradient required?

A. Ground water flow direction varies regionally and locally. NMED uses the survey and map to determine whether the monitoring wells are placed correctly.

Q. How do I sample a monitoring well?

A. This handout gives a good example. Also, this chart lets you calculate the purge water volume.

Q. What if I try to sample my monitoring well but it is dry?

A. If the well goes dry while you’re purging, wait until it fills up again and continue. If it takes a very long time to recover, you may have to reduce the amount of water you purge before collecting a sample (contact NMED to discuss this.) Make sure to note the volume of water you were able to purge before sampling and the reason it’s less than the required purge volume. Submit this information with your monitoring report.

If the well is dry when you start the sampling process, make note of the well number, location, and total depth and report it as dry to NMED when you submit your monitoring report. If the well continues to be dry for several consecutive sampling periods, you may be required to drill a new well.