Bend staff outline draft stormwater master plan, emphasize groundwater protections and programmatic approach

City of Bend staff on June 23 presented an update on the draft stormwater master plan, highlighting the city’s largely dispersed stormwater system, the need to protect groundwater and drinking-water sources, and a mix of capital investments and programmatic actions the city plans to pursue.

The draft update estimates roughly $22,000,000 in capital implementation over the next 5 to 20 years and places a strong emphasis on programmatic solutions — including drill-hole decommissioning, retrofits and a major maintenance program — because much of Bend’s public system consists of widely dispersed dry wells rather than continuous collection pipes. Staff said the plan also recommends updates to design criteria to reflect more intense and frequent storms driven by climate change.

Lori Bea, the city’s environmental resources manager, said Bend’s geology — much of the city sits on fractured basalt — means “most of it is dispersed” and stormwater is handled by dry wells and drill holes rather than a single collection system. Bea said the public system includes about 7,000 city-managed dry wells and that private dry wells on private property are not shown on the public map.

Austin, the city project manager for the stormwater master plan, summarized the capital-program development and policy work. He told the subcommittee that project teams used stakeholder scoring and workshops to prioritize sites and that the draft toolkit of projects and “high level cost estimates” will be finalized in the coming weeks. Austin said the capital program and associated toolkits reflect both drainage projects (local flooding relief) and water-quality projects (discharges to the Deschutes River).

Staff said programmatic measures are central to the plan because of the dispersed nature of the system. The update identifies 18 failing underground injection controls (UICs) and a set of priority drill holes; roughly 17 highest-priority drill holes were highlighted because they lie in two-year time-of-travel zones for municipal drinking water wells. Austin described a proposed “modified dry well” design intended to provide deeper infiltration while maintaining separation from groundwater.

The plan responds to regulatory requirements. Bea said Bend operates under two Oregon Department of Environmental Quality permits — one for discharges to the river and one for underground injection — and those permits drive requirements for erosion control, site-level treatment or pretreatment, street sweeping, illicit-discharge programs, monitoring and public education. Bea said the city’s river-based permit was last reissued in 2021 and that DEQ is in the process of reissuing the city’s underground injection permit.

Council members asked about long-term pollutant risks in dry wells and about maintenance. In one exchange, a council member asked whether dry wells are “sustainable in the long term for the kinds of pollutants that aren’t adequately … trapped or immobilized.” Austin replied that newer standards call for a pre-treatment sedimentation manhole to settle sediment and prevent oil and grease from entering injection points, and that staff had commissioned groundwater protectiveness modeling to understand how persistent pollutants such as PFAS might move underground. Bea said pretreatment features require regular maintenance and that “there’s no such thing as a no-maintenance facility.”

The update also addresses climate and data gaps. Staff recommended updating the storm-event design basis — staff noted the NOAA Atlas II precipitation data used for current design criteria was last updated in 1973 — and described a planned effort to add six AgriMET/Bureau of Reclamation monitoring stations in Bend to collect local precipitation data for future design updates.

On policy, staff described an effort to address “drainage density” as infill and higher lot coverage produce more impervious surface. The plan recommends earlier and higher-level stormwater review during development, clearer enforcement of existing code, and consideration of larger, shared stormwater facilities that could be publicly owned and maintained as subdivisions and redevelopment occur. Staff also flagged potential use of fee-in-lieu options for small infill sites.

Staff said the draft will undergo internal review, stakeholder follow-up and posting to the project web page in the coming weeks. A staff memo presented to the subcommittee said the plan had been expected to go to council in September; staff now expect to incorporate the master plan into a public facility plan appendix and anticipate taking it to council a few months later, with cost-of-service and rate implications to follow in the next rate cycle.

The subcommittee paused for questions after staff presented the draft and supporting analysis; staff recommended continued stakeholder engagement as the city finalizes the toolkits and policy recommendations.