Based on the label alone, I'd caution against using near water. I'm far from an expert though, so correct me if I'm wrong.
PRECAUTIONS:
- It is permissible to treat non irrigation ditch banks, seasonally dry wetlands, flood plains, deltas, marshes, swamps, bogs, and transitional areas between upland and lowland sites. Do not apply to open water such as lakes, reservoirs, rivers, streams, creeks, saltwater bays, or estuaries.
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Environmental Fate
The half-life of triclopyr in soils ranges from
30 to 90 days with a typical time of 46 days
For comparison:
Glyphosate's half-life (the time it takes for half of the active ingredient to degrade) is
between 3 days and 19 weeks depending on water conditions. Glyphosate disperses rapidly in water so dilution occurs quickly, thus moving water will decrease concentration, but not half-life.