County completes Tanglewood waterway work to reduce sediment and debris entering Long Lake

Polk County Land and Water staff presented the completed Tanglewood Trail waterway project, a TRIM‑grant funded installation in the Balsam Lake/Long Lake watershed intended to stop gully erosion and debris from reaching Long Lake.

Trent Kitchenmeister, conservation staff, described survey and design work that began after the gully and culvert erosion were identified in 2020–2021. Construction bids were taken in 2024; the lowest qualified bid was $22,050 and final invoiced cost rose to $29,005.89 after additional rock and materials. The grant covered 70% of the cost ($20,712.30), and the Long Lake Protection and Rehabilitation District covered $8,876.70, Kitchenmeister said. Work included clearing, plunge pools, a lined sediment basin, riprap, turf reinforcement matting and final seeding. Staff used a turf reinforcement product and keyed riprap into spillways to dissipate flow.

Staff estimated pollution reductions from the installed practices at about 19 pounds of phosphorus per year, roughly 354 pounds of nitrogen and about 90 tons of sediment annually based on modeling. Kitchenmeister noted that plunge pools will eventually require maintenance or sediment removal and that operation and maintenance obligations are included in owner contracts.

Why it matters: The project reduced direct sediment delivery and large debris reaching Long Lake, improved roadside culvert function and used a combination of state TRIM grant funds and local lake district funds to cover construction costs. Staff said the site now vegetates well and the mats allowed rapid grass establishment.