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Estimated Densities of Residential Septic Tanks across the Conterminous United States for 12-digit Hydrologic Unit Code 12 (HUC12), National Hydrography Dataset Plus Version 2 (NHDPlusV2) Catchment, and Block Group Scales

Dates

Publication Date
Time Period
2024

Citation

Peterson, B.K., Gordon, S.E., Williams, B.M., Atkins, R.M., Ahmed, L., and Seawolf, S.M., 2025, Estimated Densities of Residential Septic Tanks across the Conterminous United States for 12-digit Hydrologic Unit Code 12 (HUC12), National Hydrography Dataset Plus Version 2 (NHDPlusV2) Catchment, and Block Group Scales: U.S. Geological Survey data release, https://doi.org/10.5066/P1WCYDPB.

Summary

This dataset provides estimates of residential septic tank densities at 12-digit Hydrologic Unit Code (HUC12), National Hydrography Dataset (NHD Plus version 2.1, 1:100k scale) catchment, and 2020 Census Block Group (version 2021) scale for the conterminous United States. Using United States Legacy Census data from the 1990s and the land use classification from the National Land Cover Database (NLCD), predictive thresholds for wastewater treatment types, such as septic or sewer systems, were developed and applied to the 2020 Census and 2019 NLCD data . The dataset contains three qualitative measures, e.g., High, Medium and Low density estimates, for sewer-supported areas and septic tanks by Census Block Groups using the predictive [...]

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Attached Files

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BG2021_PotMissing_Parcels.csv 22.32 KB text/csv
BG2021_PotMissing_Parcels.parquet 11.08 KB application/unknown
BG2021_SepticDensities.csv 9.18 MB text/csv
BG2021_SepticDensities.parquet 4.02 MB application/unknown
BG2021_SewerEstimates.csv 7.76 MB text/csv
BG2021_SewerEstimates.parquet 1.64 MB application/unknown
HUC12_SepticDensities.csv 7.3 MB text/csv
HUC12_SepticDensities.parquet 3.46 MB application/unknown
NHD_SepticDensities.csv 86.48 MB text/csv
NHD_SepticDensities.parquet 36.52 MB application/unknown

Purpose

Residential septic tanks are among the most common methods used to treat wastewater on-site at homes or other buildings. When poorly maintained or improperly sized, septic tanks are potential sources of contaminants to groundwater and streams. Malfunctioning septic tanks can lead to leakage or improper treatment of effluent, resulting in the release of nutrients, bacteria, and other pollutants (for example, disinfection by-products) into groundwater and surface water systems. These releases could have negative impacts on ecosystems and human health. Thus, an understanding of septic tank locations on the landscape is needed to develop a comprehensive understanding of potential sources of contaminants and improve pollutant prediction capabilities and vulnerability modeling. Previous national-scale inventories of septic tanks have been conducted by the U.S. Census Bureau American Community Survey. However, these efforts were halted after the 1990 census, creating a data gap for accurate nation-wide septic tank estimates. To mitigate this gap, the U.S. Geological Survey (USGS) Environmental Health Program’s Geospatial Analysis and Applications Core Technology Team has developed a new method for estimating septic tank densities at multiple watershed scales for the conterminous United States.

Rights

This work is marked with Creative Commons Zero v1.0 Universal (https://creativecommons.org/publicdomain/zero/1.0/).

Additional Information

Identifiers

Type Scheme Key
DOI https://www.sciencebase.gov/vocab/category/item/identifier doi:10.5066/P1WCYDPB

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