The DNREC Division of Water creates and maintains geospatial data related to its regulatory, permitting and research activities to protect and manage Delaware’s water resources. This page lists and links to public-facing geospatial data managed by the Division.

These data sets are available via FirstMap, Delaware’s enterprise Geographic Information System (GIS), which brings together data in map form for use by state agencies, local governments, academia and the public. FirstMap is closely related to the Delaware Open Data Portal. Both are managed by the Delaware Department of Technology and Information.

Please let us know if you find any inaccuracies or issues with our data. Use the Division of Water Data Correction Form to submit a report.

About Geospatial Data

Geospatial datasets are a combination of location information (where things are) and attribute data (what we know about those things). The Division of Water’s geospatial datasets show where water‑related facilities, activities and resources are located across the state, helping users see patterns, understand relationships and make informed decisions about water management and environmental conditions.

Each dataset includes a brief description, a link to an easy‑to‑use map viewer, and a link to metadata for that data layer. GIS tool users can copy the metadata link (right click / copy link address) to import the data into their systems.

Note: When using the map links, be aware that not all of these datasets will be visible when the map is zoomed-out to the “state” level. You may need to zoom-in to see the data.

Geospatial Datasets

Biosolids and Residuals

Treating wastewater creates certain by‑products, called biosolids, as well as other non‑hazardous materials. Under specific conditions, these materials can be safely used to improve soil through land application.

This dataset shows the locations in Delaware where permits have been issued allowing biosolids or non‑hazardous wastewater residuals to be applied to land.

Groundwater Management Zones

Groundwater Management Zones, or GMZs, are areas where groundwater quality may be reduced or at risk. These zones help identify places where extra attention or precautions are needed. In some GMZs, there are specific rules, about installing wells or using groundwater, to help protect public health and the environment.

GMZ information has been collected since the 1990s and is updated from time to time. The “publication date” reflects the most recent update to the GMZ’s metadata.

Industrial Stormwater Facilities

This dataset shows the boundaries of industrial sites that are permitted and monitored by the Division of Water to manage stormwater. These locations are mapped as part of an effort to accurately identify all permitted facilities.

Having these sites clearly mapped helps staff build institutional knowledge and supports partner agencies and the public understanding where industrial stormwater activities take place.

Irrigated Areas

The Irrigated Areas dataset shows fields in Delaware that are known to use irrigation. This dataset was created through a joint effort between the University of Delaware and DNREC to establish a reliable baseline of irrigated land across the state.

DNREC will continue to update and expand this information as new irrigation system permits are issued.

Large Onsite Wastewater and Spray Irrigation Systems

The Division of Water reviews and approves spray irrigation wastewater systems and onsite wastewater treatment systems that handle more than 2,500 gallons of wastewater per day. The Division also oversees Underground Injection Control (UIC) wells and other types of wastewater treatment systems. These permits fall into two groups: Septic‑UIC and Septic‑Non‑UIC.

Non-Public Wells

This dataset shows all privately owned wells in Delaware that have been issued permits by the Division of Water’s Residential Services Section. It includes a variety of well types used for drinking water, irrigation, geothermal systems and other private purposes.

Permitted Septic Systems

This dataset includes all septic systems that are reviewed and permitted for both small systems and larger systems serving multiple structures, as long as they handle less than 2,500 gallons of wastewater per day.

Pivot Area Centroids

The Pivot Area Centroids dataset was created through a joint mapping effort between the University of Delaware and DNREC as part of the Irrigated Areas project. The Irrigated Areas dataset provides a baseline map of irrigated fields in Delaware, which DNREC will continue to update as new irrigation permits are issued.

The Pivot Area Centroids represent the center points of circular irrigation systems and are used to generate the circular field shapes shown in the Irrigated Areas dataset.

Septic Site Evaluations

This dataset includes site evaluations for septic systems that have been permitted within the Division of Water. These evaluations document the conditions and suitability of a property for installing a septic system and are part of the overall permitting process.

Septic Soil Borings

Septic soil borings are mapped to help DNREC staff review permit applications and assist in Site Evaluations, Feasibility Studies and Soil Investigation Reports. This dataset can also be useful for other divisions within DNREC, partnered agencies and the public.

Soil Feasibility Studies

This dataset shows polygons that represent areas where licensed soil scientists have conducted feasibility studies for septic systems. A feasibility study in the context of septic systems is an early‑stage evaluation that helps determine whether a property is suitable for an onsite wastewater treatment system.

Wellhead Protection Areas

This dataset maps the land areas surrounding public water supply wells that require protection to help maintain the quality and quantity of drinking water. The polygons identify zones where certain activities may pose a risk to public water sources, allowing local and state agencies to better manage and safeguard these critical areas.