Maui County unveils hydraulic model to map water-system needs

Maui County’s Water and Infrastructure Committee on Feb. 3 received a briefing on a new hydraulic-modeling tool that the Department of Water Supply (DWS) and consultants say will let staff simulate pressures, fire flow, storage and pipeline capacity across the county’s five water systems.

The model, developed by Carollo Engineers and implemented in the InfowaterPRO software, contains mapped pipeline data, tanks, pump stations, groundwater wells and demand patterns. James Jensen, engineering program manager for the Department of Water Supply, said the tool will allow staff to perform analyses “that simply were not practical in the past.”

The presentation matters because the model can be used to test whether the county’s potable water network meets regulatory and internal standards, to assess how the system would serve the county’s adopted land-use plans and to inform operational decisions such as planned tank outages, the presenters said.

Carollo’s project manager, Matt Huang, described the technical scope: the consultant converted older CAD records into GIS, built and calibrated five separate hydraulic models—Lahaina, Molokai, Central, Upcountry and East Maui—and used field data from SCADA, temporary flow meters and pressure loggers to align the model with observed conditions. Huang said the software can simulate about one day of operation in roughly 30 seconds.

Committee members were shown examples of how the model can be applied: estimating fire-flow availability for new developments or critical facilities; prioritizing pipe upsizing where small-diameter mains (commonly under 6 inches) limit fire flow; evaluating whether new or existing groundwater wells would improve pressures and tank levels; and simulating the system response when a tank is taken offline for maintenance.

Jensen and other presenters said the county will use the model to refine its capital improvement program (CIP) and to inform development review. Jensen said Carollo will provide input to the CIP and will deliver model training so DWS staff can operate and maintain the model in-house. "We will be conducting hydraulic model training with DWS staff," Jensen said.

Committee members asked about timing, staffing and funding. Jensen said the five models are complete and ready for use; the Central District model is the largest. The department’s engineering complement was discussed: Jensen said the division has 16 engineering positions, with 13 currently filled, and that the department will continue to rely on consultants to deliver large projects while training staff to maintain the model.

On funding, presenters said DWS is pursuing multiple sources, including FEMA hazard-mitigation grants, EPA funding, the Bureau of Reclamation, the state revolving fund and county revenue streams such as GET (general excise tax). Committee members were told some projects—such as a replacement for a storm-exposed main in a gulch—are at about 80% design and may be bid this year; applicants remain engaged with federal grant processes.

Council members pressed for practical outcomes. Examples given by staff included faster, same-day fire-flow assessments for the Fire Prevention Bureau (versus multi-day hand calculations), the ability to plan temporary tank outages with known impacts on pressure and fire flow, and a tool to evaluate where additional well connections would most benefit system performance. Matt Huang said the model lets engineers “play a little bit of guess and check” to compare options rapidly.

Presenters emphasized that the model complements—but does not replace—condition assessments and field knowledge. Carollo’s scope included a condition assessment of treatment plants, wells, tanks and booster stations; staff emphasized that leak history and material degradation remain separate inputs when prioritizing replacement projects.

No formal committee votes were taken. Members did not object to the department continuing work on the model, incorporating its findings into the CIP and pursuing staff training and future system master plans.

The department intends to update and maintain the model regularly; presenters described a likely maintenance cadence of roughly every six to 12 months, plus immediate updates after major system changes. Next steps identified by DWS and Carollo include training county staff, integrating model outputs into the CIP and developing system master plans to test full build-out under adopted land-use policies.

Committee Chair Tom Cook thanked the presenters and the meeting was adjourned after members signaled no objection to deferring further action while the department continues work.