EPA Sole Source Aquifer Screener — SDWA 1424(e) Review
Pricing
from $3.30 / 1,000 results
EPA Sole Source Aquifer screener. Batch point-in-polygon check of coordinates against EPA Sole Source Aquifers: returns whether each point is in an SSA, the aquifer name, project-review-area type (recharge vs streamflow source zone), Federal Register citation and EPA region for SDWA 1424(e) review.
Pricing
from $3.30 / 1,000 results
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Developer
Kyle Maloney
Maintained by CommunityActor stats
0
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2
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1
Monthly active users
2 days ago
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Asset label
asset_label
Optional
Caller-supplied label for the screened point (auto-generated if omitted).
Latitude
asset_lat
Optional
Screened point latitude (WGS84).
Longitude
asset_lon
Optional
Screened point longitude (WGS84).
In Sole Source Aquifer
in_sole_source_aquifer
Optional
True if the point falls inside any EPA-designated Sole Source Aquifer polygon; false only when the layer was queried successfully and returned no match. Null means not checked (invalid coordinate, or the layer did not answer) - see ssa_layer_status. Null is never a negative.
Requires SDWA 1424(e) review
requires_swda_1424e_review
Optional
True when in a Sole Source Aquifer: a project receiving federal financial assistance at this location is subject to EPA review under Safe Drinking Water Act section 1424(e). False only on a verified clear; null when not checked.
SSA name
ssa_name
Optional
Name of the primary (largest-area) matching Sole Source Aquifer polygon.
SSA ID
ssa_id
Optional
EPA SSA identifier of the primary matching polygon (zone suffix a/b for split aquifers).
Project-review-area type
review_area_type
Optional
Type of SSA project-review area for the primary polygon, derived from the SSA name: Recharge Zone, Streamflow Source Zone, Streamflow and Recharge Source Zone, Artesian Zone, Source Area, or the overall Aquifer Project Review Area.
Federal Register citation
federal_register_citation
Optional
Federal Register citation of the SSA designation for the primary polygon.
EPA region
epa_region
Optional
EPA region responsible for the primary matching aquifer (raw label).
EPA region number
epa_region_number
Optional
Numeric EPA region (1-10) parsed from the region label.
EPA link
epa_link
Optional
EPA regional-office contact URL for the Sole Source Aquifer program.
Matched aquifer count
matched_aquifer_count
Optional
Number of distinct SSA polygons the point falls inside (a point can be in both a recharge and a streamflow source zone). Null when the layer was not successfully queried.
Matched aquifers
matched_aquifers
Optional
All distinct SSA polygons containing the point, each with SSA id, name, project-review-area type, whether that name is in the pinned vocabulary, Federal Register citation, EPA region(s), EPA link, polygon area, perimeter and feature id. Empty array on a verified clear; null when not checked.
Error
error
Optional
Error message for an invalid coordinate or a failed query; null on success.
Disclaimer
disclaimer
Optional
Informational-use disclaimer; confirm the designation with the EPA Regional Office.
Source URL
source_url
Optional
EPA Sole Source Aquifers FeatureServer layer used.
Checked at
checked_at
Optional
UTC timestamp of the screening run.
SSA layer status
ssa_layer_status
Optional
Per-source outcome for the EPA Sole Source Aquifer point-in-polygon query on this row: "ok" (the layer answered), "unavailable" (the query failed - every aquifer verdict on this row is null, never false), "not_applicable" (the input coordinate was invalid) or "not_checked".
SSA layer error
ssa_layer_error
Optional
Upstream error text when ssa_layer_status is "unavailable"; null otherwise.
Proximity status
proximity_status
Optional
Per-source outcome for the boundary-distance query: "ok", "unavailable" (distance fields stay null rather than being guessed), "not_requested" (proximityAnalysis was off), "not_applicable" or "not_checked".
Proximity error
proximity_error
Optional
Upstream or projection-guard error text when proximity_status is "unavailable"; null otherwise.
Layer name
layer_name
Optional
Name of the EPA SSA feature layer actually queried, read live from the service. Drift evidence: if EPA republishes under a new name this changes.
Layer polygon count
layer_polygon_count
Optional
Total polygons in the live EPA SSA layer at run time, asserted to be inside the validated band (80-200; 97 as of 2026-08-01) before any row was emitted.
Data vintage
data_vintage
Optional
Edition of the EPA national Sole Source Aquifer polygon layer behind this row.
Query basis
query_basis
Optional
The exact spatial query used, recorded so a result is reproducible and auditable. inSR=4326 is load-bearing: without it the service returns an empty feature list that is indistinguishable from a genuine clear.
SDWA 1424(e) implication
sdwa_1424e_implication
Optional
Plain-language statement of what this result means under Safe Drinking Water Act section 1424(e) - what review is triggered, by what, and what it is not. Null when the aquifer status was not verified.
Review-area type verified
review_area_type_known
Optional
True when the primary polygon's SSA_NAME is in this actor's pinned vocabulary of the 94 names EPA publishes, i.e. review_area_type has been validated against that exact string rather than falling through a string-parse default. An unknown name fails the whole run before billing.
Primary SSA area (m2)
primary_ssa_area_m2
Optional
Mapped area of the primary matching SSA polygon in square metres (Web Mercator). v1.0 fetched this to choose the primary polygon and then discarded it; it is the fastest way to tell a small island aquifer from a regional system.
Primary SSA perimeter (m)
primary_ssa_perimeter_m
Optional
Mapped perimeter of the primary matching SSA polygon in metres. Fetched by v1.0 via outFields=* and never emitted.
Primary SSA feature id
primary_ssa_feature_id
Optional
Stable ArcGIS OBJECTID (FID) of the primary matching polygon, for joining back to the EPA layer or citing an exact feature in a report.
EPA regions matched
epa_regions_matched
Optional
Every distinct EPA_Region value across all matching polygons. EPA publishes SSA49b three times with regions "Region 8", "Region 9" and blank; v1.0 kept whichever arrived first and dropped the rest, so the emitted region was arbitrary among conflicting values.
EPA region conflict
epa_region_conflict
Optional
True when the matching polygons disagree about which EPA region owns the aquifer, i.e. epa_region is one of several published values and the regional office should be confirmed from epa_link rather than trusted.
Search radius (miles)
search_radius_mi
Optional
Radius used for the boundary-distance query. Distances are only reported inside this radius.
SSA polygons within radius
ssa_polygons_within_radius
Optional
Count of SSA polygons whose geometry falls within search_radius_mi of the point. 0 on a clear site with nothing nearby.
Distance to nearest SSA (m)
distance_to_nearest_ssa_m
Optional
For a point OUTSIDE every SSA: shortest distance in metres to the nearest Sole Source Aquifer boundary within the search radius. Null when inside an SSA, when nothing is within the radius, or when proximity_status is not "ok".
Distance to nearest SSA (mi)
distance_to_nearest_ssa_mi
Optional
The same distance in statute miles.
Nearest SSA id
nearest_ssa_id
Optional
SSA_ID of the nearest Sole Source Aquifer when the point is outside every SSA.
Nearest SSA name
nearest_ssa_name
Optional
Name of the nearest Sole Source Aquifer when the point is outside every SSA.
Nearest SSA review-area type
nearest_ssa_review_area_type
Optional
Project-review-area type of the nearest Sole Source Aquifer.
Nearest SSA EPA region
nearest_ssa_epa_region
Optional
EPA region of the nearest Sole Source Aquifer.
Nearest SSA Federal Register citation
nearest_ssa_federal_register_citation
Optional
Federal Register designation citation of the nearest Sole Source Aquifer.
Near an SSA boundary
near_ssa_boundary
Optional
True when the point is within nearBoundaryMi of a Sole Source Aquifer boundary - either just outside one, or just inside its edge. Boundaries are 2019-vintage and can be revised, so a near-boundary site is worth confirming with the EPA Regional Office even when in_sole_source_aquifer is false. Null when proximity was not measured.
Near-boundary threshold (mi)
near_boundary_threshold_mi
Optional
The nearBoundaryMi threshold that near_ssa_boundary was evaluated against.
Distance inside from boundary (m)
distance_inside_from_boundary_m
Optional
For a point INSIDE an SSA: how far in metres it sits from the nearest edge of that aquifer. Small values mean a boundary dispute or a survey correction could change the answer. Null when outside an SSA or when proximity was not measured.
Distance precision (m)
distance_precision_m
Optional
Stated accuracy of the distance fields in metres. Geometry is fetched generalized (maxAllowableOffset 0.0002 degrees, about 22 m), so distances are meaningful to roughly this tolerance.
Distance basis
distance_basis
Optional
Audit trail describing exactly how the distance fields were computed, including the generalization tolerance and the projection used.
