Before a beach visit

Check the state map for the latest sample date and advisory status; then follow lifeguard and weather guidance.

What DNREC tests

DNREC tests water bodies used for swimming and other recreation for Enterococcus bacteria. The organism is used as an indicator for the possible presence of other bacteria and viruses that can cause illness during activities where the head is submerged. The program is not a test for every possible pollutant, and a bacteria result should not be presented as a complete assessment of chemical contamination or ecosystem health.

Source note DNREC Recreational Water Monitoring

When samples are collected

The state says beach sampling generally runs from mid-May through mid-September. Frequency varies by site: weekly, every other week or more than once a week. Laboratory results are posted after analysis, and DNREC says results are available 24 hours after a sample is taken. Conditions can change quickly, especially after heavy rain.

Source note DNREC testing approach and timing

What an advisory means

An advisory indicates elevated bacteria results and provides guidance; it does not automatically mean a beach has been formally closed. The state describes the criteria for issuing advisories, including consecutive elevated samples at specified coastal locations. The recreational-water portal explains that advisories can also be based on a 30-day geometric mean. Check the current state map and local lifeguard guidance rather than relying on an old news report or a screenshot.

Source note Delaware Recreational Waters live map · DNREC monitoring guidance

Check the official map before swimming

Use the Delaware Recreational Waters map for current state-posted results and advisories. Select the specific beach or waterbody and check the sampling date. The map is a state resource, not an independent guarantee of conditions between samples. DNREC recommends swimming at lifeguarded beaches and consulting lifeguards and NOAA for rip currents, high surf and other hazards.

Source note DNREC recreational water guidance

Know the limits of the data

A sample represents a particular location and time. It cannot certify that every section of a beach is identical, and it cannot predict conditions after a storm or sewer overflow. Beach-water testing is also distinct from drinking-water testing: do not use a recreational-water result to evaluate tap water or a private well.