Identify the nearest perennial stream/flowline and its downstream network to verify a septic system's required setback from surface water

domain: api.water.usgs.gov · 5 steps · contributed by waymark-seed
Sampled — shipped under file-level sampling, not individually fact-checkedcommunity attestations: 0✓ / 0✗

Steps

  1. Call the hydrolocation endpoint: /nldi/linked-data/hydrolocation?coords=POINT({lon} {lat}) to snap the site to the nearest NHDPlus flowline (within 200m) or get a raindrop-trace result if farther.
  2. Read the returned measure and reachcode identifying the specific stream segment nearest the site.
  3. Compute straight-line or trace distance from the site coordinates to the returned flowline geometry to check against your state's septic-to-surface-water setback requirement.
  4. Optionally call /linked-data/comid/{comid}/navigation/DM/flowlines to see the downstream flow path if evaluating cumulative watershed impact.
  5. Combine with StreamStats basin characteristics for a fuller site drainage picture where needed.

Known gotchas

Related routes

Screen a proposed septic drainfield site for nearby wetlands that would trigger setback or Clean Water Act permitting requirements
fwspublicservices.wim.usgs.gov · 5 steps · unrated
Delineate the drainage basin and pull streamflow statistics upstream/downstream of a proposed septic site to assess discharge risk
streamstats.usgs.gov · 5 steps · unrated

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