This dataset contains 18 published records spanning 2015 through the 2026 data cut-off, matched against search terms covering small hydropower, distributed hydro generation, low-head turbines, fish-friendly design, civil-works cost, grid interconnection, flow variability and remote operation. That is a small, tightly scoped field rather than a broad one, and the assignee ranking behind it lists only four companies. Because publication lags filing by roughly 18 months, the true current total is likely somewhat higher than what has published so far.

The ranked field in this dataset covers four assignees, with the leader holding 13 of the 18 records in scope. The other three ranked assignees hold considerably fewer records each, and none show fresh filings in the most recent year captured. This is a narrow competitive set, so a new entrant should not assume the space is crowded — but should specifically screen against the leader's claims given its outsized share.

Filings peaked at 9 in 2020 and then declined, with the 2021-to-2024 window showing a -100% change from 2 filings down to 0. That 2024 figure is the most recent year reliable enough to call complete. Filings from 2025 onward are still publishing, so it would be a mistake to read the current near-zero count as proof the field has stopped moving; the honest read is that the trend is unresolved until later years catch up.

AU2016404873A1 claims an impulse-type hydro turbine that narrows the water-stream cross-section in a movable passage to convert roughly half the pressure energy into high-velocity kinetic energy, stored in a helical tube, aimed at maintaining efficiency across varying flow while simplifying flow-tracking operation. It is relevant prior art for anyone designing eddy-current speed-adjusting passages or similar pressure-to-kinetic-energy conversion mechanisms in impulse turbines. It does not, on its own, cover unrelated approaches such as reaction turbines, fish-passage geometry, or grid-interconnection control schemes.

The IPC composition shows F03B hydraulic-machine claims in 88.9% of the 18 records, while digital monitoring and control classes (G06F at 11.1%, G06G at 5.6%) and marine/civil structure classes (B63B at 16.7%) are comparatively thin. That gap suggests remote operation, flow-variability forecasting, grid-interconnection controls and civil-works cost reduction are less densely claimed than the turbine mechanics themselves, making them reasonable areas to scope a first claim before assuming the space is occupied.