Groundwater Monitoring

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.


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 Section (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)

The Department of Natural Resources and Environmental Control (DNREC) developed the notification system to promptly alert Delawareans to releases or discharges of contaminants or pollutants that meet or exceed certain thresholds in their neighborhoods or throughout the state. Anyone can register to be notified of releases in the State.

Division of Water
Department of Natural Resources and Environmental Control (DNREC)

The Division of Water manages and protects water resources through various programs by providing technical assistance, laboratory services, regulatory guidance and implementation, educational services; performing applied research; and helping finance water pollution control measures. Our staff serves through the protection of water resources for Delaware's visitors and residents.

Cleanup of Contaminated Properties - Division of Waste and Hazardous Substances
Department of Natural Resources and Environmental Control (DNREC)

The Division of Waste and Hazardous Substances oversees the handling, transferring and storing of solid and hazardous materials by regulating, monitoring, inspecting, enforcing and responding to emergencies. The Division also implements the state's permitting and compliance programs. The following Division of Waste and Hazardous Substances programs address environmental clean-up:

  • Site Investigation & Restoration Branch is responsible for the identification, evaluation and remediation of hazardous waste sites, from Brownfields to federal Superfund sites, in the State.
  • Solid and Hazardous Waste Management Branch ensures - through regulation and permitting mechanisms - that waste generated, transported, treated, recycled, reused or disposed in Delaware is managed in an environmentally safe manner. The Branch also encourages, through voluntary means, waste reduction, reuse, and recycling activities.
  • Tank Management Branch administers and assists with the installation, management of abandonment, removal and cleanup of underground and above-ground storage tank systems, to prevent contamination of soils and groundwater supplies. The staff also permits the installation and operation of vapor recovery equipment and inspects boilers and pressure vessels to ensure public safety.

Environmental Database
Department of Natural Resources and Environmental Control (DNREC)

GIS data for sites, notifications, violations and releases. There are comprehensive files available through the links on this page.

Division of Waste Management (DWM)
Industrial Site Focus

Department of Natural Resources and Environmental Control (DNREC)

This page provides links to individual industrial facilities, selected geographic areas, and sites being remediated in Delaware where the facility or site is the subject of an upcoming public workshop or hearing, or where there has been extensive public request for information. If you are interested in a specific facility or site and do not see it listed, please check the Department's Environmental Navigator or Toxics Release Inventory for facility information.

Water Conditions Summary for Delaware
Delaware Geological Survey

The Water Conditions Summary is an online monthly summary of water conditions in Delaware. Principal factors in determining water conditions are precipitation, streamflow, and groundwater levels in aquifers. Data from rain gages, stream gages, and observation wells located throughout Delaware have been collected and compiled since the 1960s by the Delaware Geological Survey. These data are displayed as hydrographs and are also available for download. In general, water is abundant in Delaware, but supply is restricted by natural geologic conditions in some areas, by contamination in others, and is dependent on precipitation.

Groundwater Data
Delaware Geological Survey

Ground-water levels are basic information needed for evaluating water conditions and for basic and applied research. For these efforts, water levels are being measured statewide in wells completed in multiple aquifers. Some wells are measured for specific projects, such as the Coastal Aquifers Salinity Project and the Water Conditions program, while other wells are measured so that staff can maintain long term records of ground-water levels for evaluation of trends.

Pesticide Compliance
Department of Agriculture (DDA)

The Delaware Department of Agriculture (DDA) Pesticide Compliance section regulates the use of pesticides in Delaware. Services provides by the DDA Pesticide Compliance section include: training, licensing, and regulating certified applicators; licensing businesses to apply pesticides commercially; registering pesticide products used in the state; collecting and recycling plastic pesticide containers; monitoring and assessing the state's shallow groundwater; performing EPA Worker Protection Standard inspections; and responding to complaints from homeowners, farmers, and others regarding concerns for health, property, and crops.

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