LEONARDTOWN, Md. — The St. Mary’s County Health Department suspended wet season perc testing effective April 17, 2026, due to declining groundwater levels observed in the county’s network of monitoring wells. The decision, announced April 20, affects property owners seeking approvals for new septic systems or expansions in Southern Maryland.
Perc testing, or percolation testing, evaluates soil absorption rates and groundwater conditions to determine suitability for onsite sewage disposal systems. These tests are required for new construction, additions and failed systems in areas without public sewer access. The wet season, typically February through May, provides the high water table conditions needed for accurate results.
All unscheduled perc test applications will carry over with priority scheduling for the next wet season, expected in 2027. Applicants may request refunds but will lose their place in line and must reapply. The Health Department’s Environmental Health Division handles scheduling and can be reached at 301-475-4321. Additional details are available at smchd.org/perc-testing.
This suspension follows a similar pause in 2025 and reflects ongoing patterns tied to seasonal and climatic variations in groundwater. Recent reports noted the Potomac River hitting near-record lows amid deepening drought conditions across the region. Monitoring wells provide critical data that ensure tests reflect real-world performance of septic systems, protecting public health and the Chesapeake Bay watershed.
In St. Mary’s County, where many rural and waterfront properties rely on septic systems, perc testing directly impacts building permits and land development. The county’s mix of residential growth, agricultural lands and sensitive environmental zones makes accurate soil and water evaluations essential. Improperly sited systems risk contaminating groundwater, streams and the bay, which supports local economies through fishing, recreation and tourism.
Health officials emphasize that the pause protects the integrity of the permitting process. Testing under inadequate groundwater conditions could lead to approvals that fail during wet periods, resulting in costly repairs or environmental violations. By waiting for suitable conditions, the department maintains standards that safeguard water quality in Southern Maryland’s rivers, creeks and estuaries.
Property owners with pending applications should contact the Environmental Health Division promptly to discuss options. Licensed septic contractors must be present during tests, and property lines need clear marking. Preparation, including clearing access paths on wooded lots, remains the applicant’s responsibility to avoid delays when testing resumes.
This year’s early suspension comes as Southern Maryland experiences variable spring weather. Similar actions in prior years, such as 2025 and 2022, allowed applications to roll over without full loss of priority. The Health Department reviews applications upon receipt and notifies owners if wet-season testing is required.
St. Mary’s County continues balancing growth with environmental protection. Public sewer expansions serve growing areas like Lexington Park, but large portions of the county depend on individual septic systems. Accurate perc testing supports sustainable development while preserving the natural resources that define the region’s quality of life.
Residents planning projects should factor potential delays into timelines. Those needing immediate information can visit the county Health Department website or call for guidance on alternative compliance paths where available. The department also provides lists of licensed septic contractors to assist with preparations.
Broader regional efforts, including those by the Chesapeake Bay Program, stress proper septic management as a key strategy for reducing nutrient pollution. In St. Mary’s, where agriculture and residential development coexist near sensitive waterways, these tests play a vital role in long-term watershed health.
The suspension underscores the importance of monitoring environmental conditions in planning infrastructure. As climate patterns shift, Southern Maryland communities adapt through data-driven decisions that balance development needs with ecological stewardship.
