Worcester County planning staff, consultant update Water Resources Element; growth areas could need about 1.9 million gallons of water/wastewater capacity

Worcester County planning staff and a consultant told the Planning Commission that the county’s Water Resources Element (WRE), last updated in 2011, is being revised with new data and scenario modeling to inform 10- and 20-year growth projections.

The consultant said the draft updates use a state web-based scenario tool and county inputs to create 10- and 20-year build-out scenarios; draft calculations show roughly 4,800 people in the planning-period growth areas and an associated need of about 1.9 million gallons of water and wastewater capacity. “This is really the sausage making portion of the comp plan process,” the consultant said, noting the team must finalize inputs before the tool’s outputs are incorporated into the report.

Why it matters: the WRE informs permit-level nutrient budgeting and infrastructure planning. County staff and the consultant said the modeled growth must be allocated by watershed so the county can evaluate nutrient loading, wastewater treatment capacity and where new public water or sewer will be needed.

The draft analysis is a build-out model based on existing zoning and county- and municipal-provided planned growth areas rather than a single population forecast. The consultant described the method as a “ground up” capacity model that calculates net developable acreage by zoning mix, applies household-size assumptions and converts dwelling-unit yields into population and service-capacity estimates. The draft uses a county average household size of 2.21 persons per dwelling unit, then reduces theoretical yields by 25 percent based on local development constraints and an established growth-model methodology.

The commission was shown an example capacity table grouped by watershed — Isle of Wight, Lower Pocomoke and Newport — and told that growth-area polygons in the draft currently lack a finalized exhibit map. The consultant said the team will produce an explicit map that links growth-area numbers to municipal or county locations and add a column in the table identifying the municipality or area associated with each growth area.

Staff stressed interdependencies with other plan elements. The WRE update will cross-reference the land-use and growth chapters and may overlap with the environmental chapter, fisheries information and the Priority Preservation Area (PPA) update. Staff said municipalities are also revising their own comprehensive plans, and the consultant noted those municipal updates informed the current build-out scenarios.

On constraints and local resource issues, county staff and the consultant said the analysis must account for: (1) areas that will remain on septic and private wells versus areas that will require public water and sewer; (2) nutrient budgets required for wastewater permits; (3) potential for saltwater intrusion and elevated chloride levels near estuaries; and (4) limited local hydrogeologic survey coverage. A county subject-matter expert said, “We’re gonna meet the nutrient budgets, obviously, on all the plants. You’ve got to.”

Speakers asked for clarity about the time horizon and the meaning of the charts. The consultant said the model is primarily a build-out capacity scenario tied to current zoning and planned growth areas; depending on how the county chooses to interpret results, the model could represent roughly 20 years of capacity or more. The consultant also said the team plans to run alternate scenarios to show different possible futures based on varying assumptions.

Staff and the consultant said some growth in the model may remain on septic and wells; county code requires larger subdivisions (projects over 100 units) to connect to public water and sewer, and current agricultural zoning restricts septic-based development (staff noted limits such as a five-unit cap per parcel for septic-based development under the existing agricultural rules). The presentation included a technical note that some surficial aquifers can show elevated nitrates and pesticides and that deeper aquifers may have iron issues that affect treatment needs.

Next steps: the consultant and staff said they will finalize the calculations, produce a labeled map tying growth-area numbers to locations, incorporate outputs from the state scenario tool and circulate draft chapters and appendices to the commission for review in the coming weeks. The commission will receive the full draft with section-by-section explanations once the back‑of‑house calculations are complete.