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Source Water Assessment Report
for the
Zuni Pueblo Water Supply System
Zuni, New Mexico

January 30, 2001

Introduction

The 1996 amendments to the Safe Drinking Water Act authorizes a Source Water Assessment Program to determine the susceptibility of a public drinking water supply to contamination. Sources of contaminants regulated by the Safe Drinking Water Act (i.e., contaminants with a Maximum Contaminant Level, contaminants regulated under the surface water treatment rule, and the microorganism cryptosporidium) are required to be inventoried during the assessment process. The EPA Region 6 Source Water Protection Branch in cooperation with your drinking water system operators has conducted this assessment for your drinking water source.

This one-time only "snap-shot" of the potential for water quality impacts to your source of drinking water is intended to serve as a starting point for you and your water supply system to initiate protection measures that will ensure an adequate quality of drinking water to meet the future needs of your Pueblo.

Background

A complete source water assessment consists of four key elements:

(1) The first step is for assessment areas to be delineated for each of the system's ground water wells or surface water intakes (see Figure 1). These delineations use available hydrogeologic factors for determining the areal extent of ground water sources for wells and the entire watershed drainage area for surface water intakes.

(2) Once the area to be assessed has been determined, a detailed potential contaminant source inventory is conducted within the delineated area. A list of potential contaminant sources and their relative risk to ground water and surface water is presented in Appendix A.

(3) The information gathered during the inventory process is then used to determine the relative susceptibility of the drinking water supply to the contaminant sources inventoried. This susceptibility determination takes into consideration four factors: (a) the physical integrity of the well/intake structure; (b) the characteristics of the hydrologic system around the well/intake; (c) characteristics of the contaminants inventoried; and, (d) the likelihood of those contaminants to reach the source of the drinking water supply. (See the "Assessment Summary" section of this report for a summary of your system's susceptibility to contamination.)

(4) The final step in conducting an assessment is for the customers using the ground water or surface water source of drinking water to be informed about the availability of the complete assessment report.

After determining the susceptibility of the ground water and/or surface water sources of the system's drinking water supply, the system's susceptibility is determined by using the arithmetic mean of the source susceptibilities. Systems that purchase their drinking water supplies from another drinking water system will share that system's susceptibility. Table A illustrates how your system's susceptibility was calculated.

Table A - System and Source Susceptibility to Contamination Determination
SourceID     Source Name      High     Medium     Low

---

W0001               F1                                       X
W0002               F2                                       X
W0003               F3                                       X
W0004               F4                                       X
W0005               Z4                                       X
W0006               Z7                                       X

---

                         System Score                      X

Assessment Summary

Your drinking water supply primary source is ground water. Your sources of drinking water come from the Chinle Formation aquifer. Based on the four susceptibility factors discussed above, your system was determined to have a MEDIUM susceptibility to contamination.

Systems with a "High" susceptibility rating are strongly encouraged to implement management controls within the source water assessment area to minimize the threat of these potential sources of contamination. Systems with a "Medium" susceptibility rating should consider implementing control measures that reduce the risk of potential contamination from sources closest to the well/intake. Systems with a "Low" susceptibility determination should initiate a public education and outreach program that focuses on protecting the drinking water resource and informing the public about activities that threaten the quality of your drinking water supply.

Figure 1:Zuni Pueblo

Conclusion

This assessment is intended to serve as a tool for you and your water supply system to use as a start to a source water protection program. To get further involved in protecting your source of drinking water, please contact your local water supply system operator to volunteer your time and talent. For additional information about the federal Source Water Assessment Program, please do not hesitate to contact Ken Williams, EPA Region 6 Source Water Protection Program Coordinator at 214.665.7129 or e-mail him at williams.ken@epa.gov.

Water Supply System Name: Zuni Pueblo
PWS ID: 063501124

Well Name [Number]: F1 [W0001]

The well depicted below was completed on an unknown date. The well was drilled to a total depth of 572.0 feet and is completed in the Chinle Formation aquifer between the screened intervals of 150.0 and 399.0 feet. The Chinle Formation aquifer is composed of sandstone and the well is currently active. This type of aquifer is rated as having a LOW susceptibility to contamination.

An inventory of potential contaminant sources (PSOC) within a 1/4 mile (1,320 feet) radius of the well reveals the following contaminant sources and their relative risk to the well:

---

The cumulative risk associated with these PSOCs is HIGH.

The overall risk of a particular PSOC is based on the type of PSOC (1=low, 2-medium, 3=high), and the risk due to the proximity of the PSOC to the water source. The distance factor is considered high (3) if the PSOC is within 810 feet, medium (2) if from 811 feet to 1070 feet, and low (1) if from 1070 feet to 1320 feet. These two components (type and distance) are summed to give the overall risk posed by the individual PSOC (low=2, 3; medium=4, 5; high=6). To determine the cumulative risk to the water source posed by all of the PSOCs, the overall risk from each source is summed and a scale is applied. If the sum is 0 to 6, the risk is low; a sum of 7 to 12 yields a medium risk; and a sum greater than 12 represents a high risk of contamination of the water source.

---

Based on the questions above, the Source Integrity Susceptibility Score is LOW.

Based on the character of the hydrogeologic factors around the setting; the nature of these potential contaminant sources, and their proximity to the well; and the physical integrity of the well; this well has been determined to have a MEDIUM susceptibility to contamination.

Water Supply System Name: Zuni Pueblo
PWS ID: 063501124

Well Name [Number]: F2 [W0002]

The well depicted below was completed on an unknown date. The well was drilled to a total depth of 514.0 feet and is completed in the Chinle Formation aquifer between the screened intervals of 180.0 and 500.0 feet. The Chinle Formation aquifer is composed of sandstone and the well is currently active. This type of aquifer is rated as having a LOW susceptibility to contamination.

An inventory of potential contaminant sources (PSOC) within a 1/4 mile (1,320 feet) radius of the well reveals the following contaminant sources and their relative risk to the well:

---

The cumulative risk associated with these PSOCs is HIGH.

The overall risk of a particular PSOC is based on the type of PSOC (1=low, 2-medium, 3=high), and the risk due to the proximity of the PSOC to the water source. The distance factor is considered high (3) if the PSOC is within 810 feet, medium (2) if from 811 feet to 1070 feet, and low (1) if from 1070 feet to 1320 feet. These two components (type and distance) are summed to give the overall risk posed by the individual PSOC (low=2, 3; medium=4, 5; high=6). To determine the cumulative risk to the water source posed by all of the PSOCs, the overall risk from each source is summed and a scale is applied. If the sum is 0 to 6, the risk is low; a sum of 7 to 12 yields a medium risk; and a sum greater than 12 represents a high risk of contamination of the water source.

---

Based on the questions above, the Source Integrity Susceptibility Score is LOW.

Based on the character of the hydrogeologic factors around the setting; the nature of these potential contaminant sources, and their proximity to the well; and the physical integrity of the well; this well has been determined to have a MEDIUM susceptibility to contamination.

Water Supply System Name: Zuni Pueblo
PWS ID: 063501124

Well Name [Number]: F3 [W0003]

The well depicted below was completed on an unknown date. The well was drilled to a total depth of 556.0 feet and is completed in the Chinle Formation aquifer between the screened intervals of 244.0 and 546.0 feet. The Chinle Formation aquifer is composed of sandstone and the well is currently active. This type of aquifer is rated as having a LOW susceptibility to contamination.

An inventory of potential contaminant sources (PSOC) within a 1/4 mile (1,320 feet) radius of the well reveals the following contaminant sources and their relative risk to the well:

Possible Sources Of Contamination (PSOC) Description	PSOC Risk	Distance From Water Source (ft)	Overall Risk
PGR - Paved/Gravel Local Road	LOW	173	MED
PGR - Paved/Gravel Local Road	LOW	321	MED
PGR - Paved/Gravel Local Road	LOW	499	MED
PGR - Paved/Gravel Local Road	LOW	600	MED
SHW - State Highway	MED	942	MED
AFL - Animal Feeding Area / Pens - Low Risk	LOW	968	LOW
UST - Underground Storage Tank	HIGH	974	MED
AFL - Animal Feeding Area / Pens - Low Risk	LOW	1,256	LOW
AFL - Animal Feeding Area / Pens - Low Risk	LOW	1,275	LOW
AFL - Animal Feeding Area / Pens - Low Risk	LOW	1,275	LOW
AFL - Animal Feeding Area / Pens - Low Risk	LOW	1,300	LOW
CEM - Cemetery	LOW	1,300	LOW

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The cumulative risk associated with these PSOCs is HIGH.

The overall risk of a particular PSOC is based on the type of PSOC (1=low, 2-medium, 3=high), and the risk due to the proximity of the PSOC to the water source. The distance factor is considered high (3) if the PSOC is within 810 feet, medium (2) if from 811 feet to 1070 feet, and low (1) if from 1070 feet to 1320 feet. These two components (type and distance) are summed to give the overall risk posed by the individual PSOC (low=2, 3; medium=4, 5; high=6). To determine the cumulative risk to the water source posed by all of the PSOCs, the overall risk from each source is summed and a scale is applied. If the sum is 0 to 6, the risk is low; a sum of 7 to 12 yields a medium risk; and a sum greater than 12 represents a high risk of contamination of the water source.

---

Based on the questions above, the Source Integrity Susceptibility Score is LOW.

Based on the character of the hydrogeologic factors around the setting; the nature of these potential contaminant sources, and their proximity to the well; and the physical integrity of the well; this well has been determined to have a MEDIUM susceptibility to contamination.

Water Supply System Name: Zuni Pueblo
PWS ID: 063501124

Well Name [Number]: F4 [W0004]

The well depicted below was completed in January, 1978(*). The well was drilled to a total depth of 490.0 feet and is completed in the Chinle Formation aquifer between the screened intervals of 390.0(*) and 450.0(*) feet. The Chinle Formation aquifer is composed of sandstone and the well is currently active. This type of aquifer is rated as having a LOW susceptibility to contamination

An inventory of potential contaminant sources (PSOC) within a 1/4 mile (1,320 feet) radius of the well reveals the following contaminant sources and their relative risk to the well:

---

The cumulative risk associated with these PSOCs is HIGH.

The overall risk of a particular PSOC is based on the type of PSOC (1=low, 2-medium, 3=high), and the risk due to the proximity of the PSOC to the water source. The distance factor is considered high (3) if the PSOC is within 810 feet, medium (2) if from 811 feet to 1070 feet, and low (1) if from 1070 feet to 1320 feet. These two components (type and distance) are summed to give the overall risk posed by the individual PSOC (low=2, 3; medium=4, 5; high=6). To determine the cumulative risk to the water source posed by all of the PSOCs, the overall risk from each source is summed and a scale is applied. If the sum is 0 to 6, the risk is low; a sum of 7 to 12 yields a medium risk; and a sum greater than 12 represents a high risk of contamination of the water source.

---

Based on the questions above, the Source Integrity Susceptibility Score is LOW.

Based on the character of the hydrogeologic factors around the setting; the nature of these potential contaminant sources, and their proximity to the well; and the physical integrity of the well; this well has been determined to have a MEDIUM susceptibility to contamination.

(*) Estimated value based on Best Professional Judgement.

Water Supply System Name: Zuni Pueblo
PWS ID: 063501124

Well Name [Number]: Z4 [W0005]

The well depicted below was completed on an unknown date. The well was drilled to a total depth of 220.0 feet and is completed in the Chinle Formation aquifer between the screened intervals of 120.0(*) and 210.0(*) feet. The Chinle Formation aquifer is composed of sandstone and the well is currently active. This type of aquifer is rated as having a LOW susceptibility to contamination.

An inventory of potential contaminant sources (PSOC) within a 1/4 mile (1,320 feet) radius of the well reveals the following contaminant sources and their relative risk to the well:

---

The cumulative risk associated with these PSOCs is HIGH.

The overall risk of a particular PSOC is based on the type of PSOC (1=low, 2-medium, 3=high), and the risk due to the proximity of the PSOC to the water source. The distance factor is considered high (3) if the PSOC is within 810 feet, medium (2) if from 811 feet to 1070 feet, and low (1) if from 1070 feet to 1320 feet. These two components (type and distance) are summed to give the overall risk posed by the individual PSOC (low=2, 3; medium=4, 5; high=6). To determine the cumulative risk to the water source posed by all of the PSOCs, the overall risk from each source is summed and a scale is applied. If the sum is 0 to 6, the risk is low; a sum of 7 to 12 yields a medium risk; and a sum greater than 12 represents a high risk of contamination of the water source.

---

Based on the questions above, the Source Integrity Susceptibility Score is HIGH

Based on the character of the hydrogeologic factors around the setting; the nature of these potential contaminant sources, and their proximity to the well; and the physical integrity of the well; this well has been determined to have a MEDIUM susceptibility to contamination.
(*) Estimated value based on Best Professional Judgement.

The well depicted below was completed on an unknown date. The well was drilled to a total depth of 208.0 feet and is completed in the Chinle Formation aquifer between the screened intervals of 148.0 and 198.0 feet. The Chinle Formation aquifer is composed of sandstone and the well is currently active. This type of aquifer is rated as having a LOW susceptibility to contamination.

An inventory of potential contaminant sources (PSOC) within a 1/4 mile (1,320 feet) radius of the well reveals the following contaminant sources and their relative risk to the well:

---

The cumulative risk associated with these PSOCs is HIGH.

The overall risk of a particular PSOC is based on the type of PSOC (1=low, 2-medium, 3=high), and the risk due to the proximity of the PSOC to the water source. The distance factor is considered high (3) if the PSOC is within 810 feet, medium (2) if from 811 feet to 1070 feet, and low (1) if from 1070 feet to 1320 feet. These two components (type and distance) are summed to give the overall risk posed by the individual PSOC (low=2, 3; medium=4, 5; high=6). To determine the cumulative risk to the water source posed by all of the PSOCs, the overall risk from each source is summed and a scale is applied. If the sum is 0 to 6, the risk is low; a sum of 7 to 12 yields a medium risk; and a sum greater than 12 represents a high risk of contamination of the water source. Based on the character of the hydrogeologic factors around the setting; the nature of these potential contaminant sources, and their proximity to the well; and the physical integrity of the well; this well has been determined to have a MEDIUM susceptibility to contamination.

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Based on the questions above, the Source Integrity Susceptibility Score is MEDIUM.

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Source Water Assessment Report
for
the Zuni Pueblo/Black Rock (IHS) Water Supply System

Zuni, New Mexico
January 30, 2001

Introduction

The 1996 amendments to the Safe Drinking Water Act authorizes a Source Water Assessment Program to determine the susceptibility of a public drinking water supply to contamination. Sources of contaminants regulated by the Safe Drinking Water Act (i.e., contaminants with a Maximum Contaminant Level, contaminants regulated under the surface water treatment rule, and the microorganism cryptosporidium) are required to be inventoried during the assessment process. The EPA Region 6 Source Water Protection Branch in cooperation with your drinking water system operators has conducted this assessment for your drinking water source. This one-time only "snap-shot" of the potential for water quality impacts to your source of drinking water is intended to serve as a starting point for you and your water supply system to initiate protection measures that will ensure an adequate quality of drinking water to meet the future needs of your Pueblo.

Background

A complete source water assessment consists of four key elements:

(1) The first step is for assessment areas to be delineated for each of the system's ground water wells or surface water intakes (see Figure 1). These delineations use available hydrogeologic factors for determining the areal extent of ground water sources for wells and the entire watershed drainage area for surface water intakes.

(2) Once the area to be assessed has been determined, a detailed potential contaminant source inventory is conducted within the delineated area. A list of potential contaminant sources and their relative risk to ground water and surface water is presented in Appendix A.

(3) The information gathered during the inventory process is then used to determine the relative susceptibility of the drinking water supply to the contaminant sources inventoried. This susceptibility determination takes into consideration four factors: (a) the physical integrity of the well/intake structure; (b) the characteristics of the hydrologic system around the well/intake; (c) characteristics of the contaminants inventoried; and, (d) the likelihood of those contaminants to reach the source of the drinking water supply. (See the "Assessment Summary" section of this report for a summary of your system's susceptibility to contamination.)

(4) The final step in conducting an assessment is for the customers using the ground water or surface water source of drinking water to be informed about the availability of the complete assessment report.

After determining the susceptibility of the ground water and/or surface water sources of the system's drinking water supply, the system's susceptibility is determined by using the arithmetic mean of the source susceptibilities. Systems that purchase their drinking water supplies from another drinking water system will share that system's susceptibility. Table A illustrates how your system's susceptibility was calculated.

Assessment Summary

Your drinking water supply primary source is ground water. Your sources of drinking water come from the Glorieta Sandstone/san Andres Limestone aquifer and the Jurassic Zuni Sandstone Formation aquifer. Based on the four susceptibility factors discussed above, your system was determined to have a MEDIUM susceptibility to contamination.

Systems with a "High" susceptibility rating are strongly encouraged to implement management controls within the source water assessment area to minimize the threat of these potential sources of contamination. Systems with a "Medium" susceptibility rating should consider implementing control measures that reduce the risk of potential contamination from sources closest to the well/intake. Systems with a "Low" susceptibility determination should initiate a public education and outreach program that focuses on protecting the drinking water resource and informing the public about activities that threaten the quality of your drinking water supply.

Conclusion

This assessment is intended to serve as a tool for you and your water supply system to use as a start to a source water protection program. To get further involved in protecting your source of drinking water, please contact your local water supply system operator to volunteer your time and talent. For additional information about the federal Source Water Assessment Program, please do not hesitate to contact Ken Williams, EPA Region 6 Source Water Protection Program Coordinator at 214.665.7129 or e-mail him at williams.ken@epa.gov.

---

---

Water Supply System Name: Zuni Pueblo/Black Rock (IHS)
PWS ID: 063502124
Well Name [Number]: BR4-PHS [W0001]

The well depicted below was completed on an unknown date. The well was drilled to a total depth of 1175.0 feet and is completed in the Glorieta Sandstone/san Andres Limestone aquifer between the screened intervals of 938.0 and 1175.0 feet. The Glorieta Sandstone/san Andres Limestone aquifer is composed of sandstone and carbonate and the well is currently active. This type of aquifer is rated as having a LOW susceptibility to contamination. An inventory of potential contaminant sources (PSOC) within a 1/4 mile (1,320 feet) radius of the well reveals the following contaminant sources and their relative risk to the well:

The cumulative risk associated with these PSOCs is HIGH

The overall risk of a particular PSOC is based on the type of PSOC (1=low, 2-medium, 3=high), and the risk due to the proximity of the PSOC to the water source. The distance factor is considered high (3) if the PSOC is within 810 feet, medium (2) if from 811 feet to 1070 feet, and low (1) if from 1070 feet to 1320 feet. These two components (type and distance) are summed to give the overall risk posed by the individual PSOC (low=2, 3; medium=4, 5; high=6). To determine the cumulative risk to the water source posed by all of the PSOCs, the overall risk from each source is summed and a scale is applied. If the sum is 0 to 6, the risk is low; a sum of 7 to 12 yields a medium risk; and a sum greater than 12 represents a high risk of contamination of the water source. Based on the character of the hydrogeologic factors around the setting; the nature of these potential contaminant sources, and their proximity to the well; and the physical integrity of the well; this well has been determined to have a MEDIUM susceptibility to contamination.

Source Integrity Parameter	Assessment
1.Is the top of the screened interval within 100 feet of ground level?	No
2. Is the casing exposed to surface water runoff?	Yes
3. Is the well site subject to flooding?	Yes
4. Is the upper termination of the well located outside a secured area?	Yes
5. Is the upper termination of the well located in a pit?	No

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Based on the questions above, the Source Integrity Susceptibility Score is HIGH

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Water Supply System Name: Zuni Pueblo/Black Rock (IHS)
PWS ID: 063502124

Well Name [Number]: BR5 [W0002]

The well depicted below was completed in January, 1988(*). The well was drilled to a total depth of 220.0 feet and is completed in the Jurassic Zuni Sandstone Formation(*) aquifer between the screened intervals of 110.0(*) and 200.0(*) feet. The Jurassic Zuni Sandstone Formation aquifer is composed of sandstone and the well is currently active. This type of aquifer is rated as having a LOW susceptibility to contamination. An inventory of potential contaminant sources (PSOC) within a 1/4 mile (1,320 feet) radius of the well reveals the following contaminant sources and their relative risk to the well:

---

The cumulative risk associated with these PSOCs is HIGH.

The overall risk of a particular PSOC is based on the type of PSOC (1=low, 2-medium, 3=high), and the risk due to the proximity of the PSOC to the water source. The distance factor is considered high (3) if the PSOC is within 810 feet, medium (2) if from 811 feet to 1070 feet, and low (1) if from 1070 feet to 1320 feet. These two components (type and distance) are summed to give the overall risk posed by the individual PSOC (low=2, 3; medium=4, 5; high=6). To determine the cumulative risk to the water source posed by all of the PSOCs, the overall risk from each source is summed and a scale is applied. If the sum is 0 to 6, the risk is low; a sum of 7 to 12 yields a medium risk; and a sum greater than 12 represents a high risk of contamination of the water source. Based on the character of the hydrogeologic factors around the setting; the nature of these potential contaminant sources, and their proximity to the well; and the physical integrity of the well; this well has been determined to have a MEDIUM susceptibility to contamination. (*) Estimated value based on Best Professional Judgement.

Based on the questions above, the Source Integrity Susceptibility Score is MEDIUM

Potential Sources of Contamination

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