Groundwater Monitoring Groundwater is water that is below the surface of the earth, residing in aquifers between layers of soil or rock. While some drinking water in Delaware comes from groundwater sources (after it has been treated), other drinking water comes from surface sources like rivers (again, treated before it is sent to homes and businesses).

The State Department of Natural Resources and Environmental Control and the federal Environmental Protection Agency regulate, monitor, enforce and respond to emergencies regarding potential contaminants in the ground that might pose a threat to the water people use.

In some areas, wells are prohibited or water use is restricted because of these issues. A good source of information about areas of concern that might be in your area is DNREC's Environmental Navigator tool or the EPA's My Environment Search Application.

But the water quality tests done by water systems or ones you have done on your own private well are the best indication about the drinking water you consume.

Additional resources relating to groundwater in Delaware are below:

The USGS annually monitors groundwater levels in thousands of wells in the United States. Groundwater level data are collected and stored as either discrete field-water-level measurements or as continuous time-series data from automated recorders. Data from some of the continuous record stations are relayed to USGS offices nationwide through telephone lines or by satellite transmissions providing access to current groundwater data. Once a complete day of readings are received from a site, daily summary data are generated and made available online. Annually, the USGS finalizes and publishes the daily data in a series of water-data reports.



Pesticides Monitoring Program
Delaware Department of Agriculture

The Delaware Department of Agriculture's Pesticide section began monitoring the state's shallow groundwater for pesticides in 1995. Since then, the Department has collected more than 1000 individual groundwater samples from over 220 domestic, agricultural, and monitoring wells. Individual samples have been screened for up to twenty-two different pesticides that are commonly used in agriculture and the commercial industry. These include alachlor, atrazine, carbofuran, chlorothalonil, chlorpyrifos, cyanazine, diazinon, dicamba, dieldrin, glyphosate, lambda-cyhalothrin, lindane, malathion, metolachlor, metribuzin, pendimethalin, picloram, simazine and the compound 2, 4-D. The majority of the wells tested negative. Much of this data is presented in a report of investigations co-authored by the Delaware Geological Survey (DGS) and the Department of Agriculture. The report is titled: Report of Investigations No. 61 entitled "The Occurrence and Distribution of Several Agricultural Pesticides in Delaware's Shallow Ground Water" and can be obtained through the Delaware Geological Survey.



Site Investigation & Restoration Branch (SIRB) Groundwater Management Zone (GMZ) List Page
Department of Natural Resources and Environmental Control (DNREC)

The state labels areas of concern Groundwater Management Zones in order to limit wells because of pollution concerns. The GMZ map and associated restrictive language define the area where DNREC will restrict water wells as detailed in a Memorandum of Agreement between the Division of Water Resources and Division of Air and Waste Management. A GMZ is put in place when there is a "technical impracticability" where the nature or extent of groundwater injury prevents remediation.

DNREC Environmental Release Notification System
Department of Natural Resources and Environmental Control (DNREC)