Des Moines Creek estuary design advances; council committee shown renderings, timeline and funding needs

The Des Moines City Council Environment Committee on Feb. 13 was shown new renderings and a refined schedule for the Des Moines Creek estuary restoration and public-space redesign, and staff said the project is funded only through 30% design and will need additional grants and permits before construction can proceed.

Tyler Weakley, surface water manager for Des Moines City, opened the briefing and introduced consultants from Parametrics, who showed plan views, low- and high-tide renderings and a planned fly-through video. Paul Fint, Parametrics project manager, and Nikki Redden, Parametrics surface water engineer, described the preferred alternative, how the different work areas fit together and design constraints such as utilities and access behind the seawall.

The consultants said the preferred design reduces the meadow area: the finished estuary footprint would reduce the meadow to about 31,000 square feet, with a possible reconnection of roughly 5,000 square feet in an upper area; Parametrics estimated that change represents about a 16% reduction in the meadow footprint. Council members asked about elevations; consultants said a proposed finished meadow elevation of about 14 feet would address most regular high tides and near-term sea-level rise impacts, compared with current high-tide elevations around 12.5 feet. The consultants cautioned that extreme events would still inundate the green, and that raising the meadow to higher elevations would trigger additional design iterations and higher costs.

Design detail: Parametrics said the estuary work would include excavation of channel veins to elevations near the 6-foot range so those channels are regularly inundated even at summer low tides; upland green areas would be at higher elevations (roughly 8 feet in the current concept). The team also described required revetments and seawall work to protect existing trails, roads and utility corridors; utilities behind the seawall will need relocation and will be a major design constraint.

Funding and timeline: Staff said the project is funded internally only through 30% design. Committee members were told staff will apply for additional grant funding this month to advance design beyond 30%. Paul Fint said the city is targeting final design in 2026 if grants and permitting proceed; consultants estimated construction implementation could take up to two years and that the work could be phased. Staff emphasized they will not begin construction on an element without funding to complete that element.

Permitting, cultural resources and sedimentation: Parametrics described cultural-resources and historic-review work as part of the design and permitting process and noted that some permits could take years. The team cautioned that estuary changes can alter where sediment deposits, and that sedimentation could require periodic removal depending on how the channel and tidal flows are altered.

Park impacts and programming: The consultants said construction access and staging would likely constrain park access during major work; staff noted the design team includes a park programmer to preserve the park's programming value while reconciling tradeoffs in geography and function.

Next steps: Committee members were told staff will bring a consultant contract to the full council under old business to fund design to 30% and that further grants and permitting will determine schedule for 60% and final design and for construction. The committee did not take a construction vote; design and construction will proceed only after further council actions, grant awards and permit approvals.

Ending: Committee members asked for cost-per-foot and other cost breakdowns for elevation changes as the design progresses; staff and the consultant said those cost iterations will become clearer at 30% and 60% design and will be shared in later briefings.