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Chapter I

In recognition of the U.S. Environmental Protection Agency's (USEPA) recently adopted ground-water protection strategy (USEPA 1991), the Water Quality Division (WQD) of the Wyoming Department of Environmental Quality (DEQ) has placed a priority on the development of a spatially-referenced database for the coordinate locations of all groundwater-based sources (i.e., wellhead and springs) for community and noncommunity public water system (PWS) facilities in Wyoming. Additionally, in order to plan and implement groundwater quality protection programs, such as the Wyoming State Wellhead Protection Program, there is a need to assemble readily available digital data related to PWS facilities and sources. A substantial amount of work has already been directed toward this goal by the USEPA through the development of the Safe Drinking Water Program Database. This relational database has an assortment of tables associated with PWS systems, including (representing): identification information, locational information, construction information, permit tracking, inspection/operation information, and enforcement/compliance tracking. To spatially reference this data, it becomes necessary that the locations for each PWS source are accurately located and incorporated within USEPA's database.

In September of 1995, the Wyoming Department of Environmental Quality, Water Quality Division (WDEQ/WQD) contracted with the Wyoming Water Resources Center (WWRC) at the University of Wyoming to establish locations for a portion of the remaining groundwater sources within the USEPA PWS database. Dates of the contract were Oct. 1, 1995 to Dec. 31, 1996 with the majority of field work being accomplished from May, 1996 to September, 1996. Within this final report the tasks and methodologies employed throughout the contract period are described.


A [Public Water System (PWS)] is a system that provides piped water for human consumption and regularly serves at least 25 persons or has at least 15 service connections. A PWS may receive its water from ground water sources, surface water sources or a combination of the two sources; in some cases, one PWS may purchase all or part of its water from another PWS, (USEPA, 1994).

Within Wyoming there are over 900 PWSs with approximately 1350 sources (i.e., surface- or ground-water) supplying water to these facilities. The two main types of PWSs are community and non-community water systems. A community water system is a PWS that serves at least 15 service connections used by year-round residents or regularly serves at least 25 year-round residents (40 CFR 141.2). In Wyoming there are currently 355 community PWSs with 92 of these owned by incorporated communities (Table 1). Approximately 455,396 people throughout Wyoming (83% of total population) receive their water from these systems. As shown in Table 2, which further divides Wyoming population figures, 288 out of 355 or 81 % of the community PWS serve populations of less than 500 people with the remaining 67 or 19% serving populations ranging from 500-55,0000.

Class of SystemNumber of SystemsTotal Population Served
Community PWS355455,396
Transient Non-Community35972,765

Table 1. Total Active Public Water Systems in Wyoming by Class
Source: USEPA Safe Drinking Water Program Database (12/15/96)

Class of System Number
Population Served by System
< 25 26 - 500 501 - 3,300 3,301 - 10,000 10,000>
Community PWS 355 3 285 43 14 10
Transient Non-
359 1 343 12 3 -
102 - 94 8 - -
Table 2. Wyoming Public Water Systems by Class and Size (surface and groundwater sources)
Source: Data collected for the WDEQIWQD 1996 Water Quality Assessment Report: 305B (Collected by Vanessa Forselius)

Non-community systems can be classified as by transient or non-transient (USEPA, 1994). These classifications are based strictly on the type of population being served by the system, and does not reflect in any way the size of this population. A transient, non-community water system is a PWS that serves at least 25 people daily, but only the same individuals for less than 6 months (e.g. campgrounds, rest areas, parks, service stations, and guest ranches (40 CFR 141.2)). There are 359 of these systems located in Wyoming serving an estimated population of 72,765 (Table 1). This population number appears small in comparison to the community systems. However, the number would greatly increase if it included all users that obtain water from the system rather than the daily number of people that use the facility. A non-transient, non- community water system is a PWS that serves at least 25 of the same persons for over 6 months of the year (e.g. schools, office buildings, and mines (40 CFR 141.2)). There are 102 non-transient non-community PWSs in Wyoming serving 19,869 people.

USEPA has different regulations for the various system classes. Community systems are subject, for the most part, to all of the USEPA's drinking water regulations as are non-transient non-community systems. Transient noncommunity facilities, where public water consumption occurs only over shor periods of time, have far fewer regulations. (For more information, see Drinking Water Standard Setting, Question and Answer Primer, USEPA, 1994)

The USEPA was mandated by the Safe Drinking Water Act (SDWA) to enforce and monitor regulation compliance of all public water systems to the specific standards established in the Act (USEPA, 1994). In order to effectively handle the large amount of data created from such a task, the Safe Drinking Water Program Database was developed for all the States and administered by each regional USEPA office. This database, as mentioned before, has a number of relational tables ranging from locational data to enforcement and compliance tracking.

For this project, two specific tables from this Database were used in reference to Wyoming. First was the system table which provides the foundation for the Database. This table contains the descriptive variables relating to each system, including the system's general locale (town, county, state), the system owner(s) or contact, type of system, activity of system, population the system serves, etc. The unique identifier for this table is the system identification number. This field is found in all other tables and is the direct link between each. The second table utilized for this project was the sources table. It contains the descriptive variables relating to the source or sources for each system: location (latitude/longitude and legal description), source type (groundwater or surface water), name of source, etc. This table uses a double- field unique identifier which is tied to the system identification number and the source identification number. This is necessary due sources having a unique source identification number that relates only to each respective system.

The primary objective of this project was to obtain and record latitude and longitude coordinates for up to 80% of the PWS groundwater sources contained within USEPA's Safe Drinking Water Program Database that had not been previously mapped. Specifically, this included three major tasks:

  1. Update and modify the system and source tables found in USEPA's database for use by Wyoming's Department of Environmental Quality, Water Quality Division.
  2. Locate PWS groundwater sources.
  3. Convert system and source tables into a usable and spatial Geographic Information System (GIS) database for DEQ/WQD.

Chapters Two through Five examine the methodologies and procedures employed in each of these tasks. Additionally, Chapter Five win identify future work relating to the use of GIS and the Safe Drinking Water Program Database.

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