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Consultant: prescribed fire and targeted herbicide needed to restore Blaine Wetland Sanctuary nd meet wetland-bank thresholds
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Summary
ISG plant ecologist William Stencil told the Natural Resource Conservation Board that monitoring at the Blaine Wetland Sanctuary found a degraded wet meadow (FQI ~15.3 vs. target 18) and recommended spring prescribed fire, followed by a grass-specific herbicide in treated zones and continued monitoring; staff noted credit generation will take years, delaying boardwalk bids.
William Stencil, a plant ecologist with ISG, presented monitoring results for the Blaine Wetland Sanctuary and said the site—ontains 122 native plant species and several high-quality communities but that the wet meadow community is seriously degraded and is blocking the wetland-bank credit timeline.
Stencil said the 171-acre site supports four native plant communities and four state-listed species. He reported an overall total of 122 native species and 14 nonnative species; the wet meadow community currently has an FQI (Floristic Quality Index) of about 15.3, below the interim target of 18 required to earn an initial wetland-credit deposit.
Why it matters: the city intends to leverage wetland-bank credits as a funding source for a planned boardwalk. Stencil told the board the wet meadow must reach an FQI of 18 for two consecutive years to earn 15% of credit deposit and that process means credit revenue is several years away, which in turn has delayed council approval to bid boardwalk construction.
Stencil recommended three management tools: 1) targeted prescribed fire in mid-spring to restore openness and stimulate native seed response, 2) post-fire, targeted application of a grass-specific herbicide (identified in the presentation as "clethodin") limited to poor-performing plots (he pointed to Plot 14) to reduce reed canary grass while protecting forbs and sedges, and 3) physical removal of woody invasives (buckthorn) and follow-up monitoring. He emphasized avoiding herbicide near open water and using buffers where ditches or open water exist.
On the herbicide nd aquatic safety, Stencil said the grass-specific product is not approved for open-water use and that legal and buffer constraints mean applications must avoid open water. He told the board the herbicide—ffects on reed canary grass show up in roughly three weeks, but he could not state precise soil persistence and recommended monitoring first for post-fire response before large-scale treatments.
Board members pressed Stencil on hydrology and nearby ditching. One committee member pointed out that Ditch 5362 (Rice Creek Watershed District) and pending development north of Site 7 could change groundwater upwelling that sustains fen conditions; Stencil confirmed that ditch cleaning or deeper dredging could affect site hydrology and the distribution of state-listed species and recommended the board notify city council and the watershed district of the concern.
Stencil also described the site's rare-plant highlights (for example, large populations of viola lanceolata and a limited occurrence of Zyris torta) and urged caution in management around high-quality plots. He recommended keeping heavy vehicles and herbicide away from high-quality rich and poor fen plots and said volunteer work (buckthorn removal, mid-July weed-whacking for thistle) could be used selectively to reduce seed banks without herbicide.
Next steps: staff and the board will continue monitoring, consider prescribed-burn planning and permitting with fire marshal and local fire departments on standby, track water-depth changes to detect hydrology shifts, and share Stencil nd ISG's PowerPoint with board members. City council direction to delay bids until wetland-bank credits materialize means construction of extensive boardwalk segments will likely wait until monitoring goals and credit milestones are met.
