Metadata for Estimated Relative Septic System Density, Montana, 1990 Metadata for Estimated Relative Septic System Density, Montana, 1990

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Identification Information:

Citation:

Originator: Montana State Library
Publication date: 04/27/2000
Title: Estimated Relative Septic System Density, Montana, 1990
Online linkage: https://ftpgeoinfo.msl.mt.gov/Data/Spatial/NonMSDI/Shapefiles/Septic_Density_1990.zip

Abstract:

These data are a re-classification of the population density of Census Blocks into estimated septic system densities of H, M, or L (High, Medium, or Low).

Areas within incorporated cities and towns are reclassified as "C", which means that the area is assumed to have a municipal waste disposal system rather than individual septic systems.

High density is defined as being areas with over 750 persons per square mile. Medium density is defined as being areas with 125 to 750 persons per square mile. Low density is defined as being areas with less than 125 persons per square mile.

Purpose:

The Federal Safe Water Drinking Act requires states to implement Source Water Assessment Programs that analyze existing and potential threats to the quality of the states' public water supplies. The Montana Source Water Protection Program (SWPP) has complied with this by publishing source water delineation and assessment reports for each public water supply. A required element of each assessment is an estimate of the septic system density in the source region. The State Library developed these data under the guidance of the SWPP and published it in the State Library Digital Atlas application so that SWPP personell and the public could view a map of the septic system density around any public water supply.

Time period of content:

Calendar date: 04/01/1990
Currentness reference: ground condition

Access constraints: None

Use constraints:

These data are for general planning purposes only. Census Block boundaries are arbitrary -- large Census Blocks may contain small areas of concentrated population and high septic system density that are not shown here.

This data set is provided "as-is" without warranty of any kind. The DEQ makes no representations or warranties whatsoever with respect to the accuracy or completeness of this data set and assumes no responsibility for the suitability of this data set for a particular purpose; and DEQ will not be liable for any damages incurred as a result of errors in this data set.

The Montana State Library provides this product/service for informational purposes only. The Library did not produce it for, nor is it suitable for legal, engineering, or surveying purposes. Consumers of this information should review or consult the primary data and information sources to ascertain the viability of the information for their purposes. The Library provides these data in good faith but does not represent or warrant its accuracy, adequacy, or completeness. In no event shall the Library be liable for any incorrect results or analysis; any direct, indirect, special, or consequential damages to any party; or any lost profits arising out of or in connection with the use or the inability to use the data or the services provided. The Library makes these data and services available as a convenience to the public, and for no other purpose. The Library reserves the right to change or revise published data and/or services at any time.

Point of contact:

Montana State Library
P.O. Box 201800
Helena, Montana 59620-1800
Telephone: 406-444-5354
TDD/TTY telephone: Montana Relay 711
Fax: 406-444-0266
E-Mail: geoinfo@mt.gov

Data Quality Information:

Lineage:

Source information:

Originator: U.S. Census Bureau
Publication date: 08/08/1992
Title: 1990 Census Blocks with Population Data
Online linkage: https://ftpgeoinfo.msl.mt.gov/Data/Spatial/NonMSDI/Collections/Census/cblock1990.zip
Source scale denominator: 100000
Source contribution:: This is the source of the 1990 Census block population density data that were re-classified as estimated septic system density.
Calendar date: 04/01/1990

Source information:

Originator: Montana State Library
Publication date: 05/03/1996
Title:: Montana Incorporated Places and Census Designated Places, 1992
Online linkage: https://ftpgeoinfo.msl.mt.gov/Data/Spatial/NonMSDI/Collections/Census/Places1992.zip
Source scale denominator: 100000
Source contribution:: This is the source of the incorporated places used to designate the "C" areas presumed to have municipal wastewater systems.
Calendar date: 04/01/1990

Process step:

Add an item to a copy of the 1990 Census Block layer and calculate the septic density value as either H, M, or L according to the population density column. Intersect the layer with a latitude/longitude grid (edited to avoid high density areas). This was done to prevent the final product from having a statewide, extremely complicated "background" polygon of low septic density. Dissolve the polygons on septic density and lat/lon grid area to eliminate lines between areas with the same population density.


Process date: 04/2000

Process step:

Select the incorporated places from the incorporated and Census designated places layer by eliminating polygons whose names include "CDP". Edit the Butte/Silver Bow and Anaconda-Deer Lodge polygons to represent the built-up area of those cities. Overlay the edited layer on the dissolved septic density layer to insert the "C" areas.


Process date: 04/2000

Spatial Data Organization Information:

Point and vector object information:

SDTS object type: G-polygon

SDTS object count: 3080

Spatial Reference Information:

Horizontal coordinate system definition:

Map projection:

Map projection name: NAD 1983 StatePlane Montana FIPS 2500
Lambert conformal conic:

Planar distance units: meter

Geodetic model:

Horizontal datum name: D North American 1983
Ellipsoid name: GRS 1980
Semi-major axis: 6378137.0
Denominator of flattening ratio: 298.257222101

Entity and Attribute Information:

Entity type label: Septic_Density_1990

Attribute label: FID

Attribute definition: Internal feature number

Attribute label: Shape

Attribute definition: Feature geometry

Attribute label: AREA

Attribute definition: Area of the polygon in square meters

Attribute label: PERIMETER

Attribute definition: Length of the polygon perimeter in meters

Attribute label: SEPDEN

Attribute definition: Septic system density classification

Distribution Information:

Distributor:

Montana State Library
PO Box 201800
Helena, MT 59620-1800
Telephone: 406-444-5354
TDD/TTY telephone: Montana Relay 711
Fax: 406-444-0266
E-Mail: geoinfo@mt.gov

Resource description: Downloadable Data

Distribution liability:

Metadata Reference Information:

Metadata date: 08/24/2015

Metadata contact:

Montana State Library
P.O. Box 201800
Helena, Montana 59620-1800
Telephone: 406-444-5354
TDD/TTY telephone: Montana Relay 711
Fax: 406-444-0266
E-Mail: geoinfo@mt.gov