The San Juan Generating Station in Waterflow, NM, owned by the Public Service Company of New Mexico (PNM) is a coal-fired power plant that operates on coal mined on the same property. This plant is scheduled to shut down in 2022. In light of this impending closure, the Bureau of Reclamation (Reclamation) is interested in purchasing the plant's raw-water reservoir for use in the Navajo-Gallup Water Supply Project (NGWSP). Concerns about contamination leaking from the reservoir or being mobilized by groundwater flow affected by the leaking reservoir have resulted in Reclamation eliciting a short study of the water and sediment chemistry surrounding the reservoir and the recovery system set up by PNM. The U.S. Geological Survey (USGS) New Mexico Water Science Center collected water and sediment samples in the area in January 2021. Water and sediment samples were sent the University of New Mexico to be analyzed in the Analytical Chemistry Laboratory (UNM-ACL) in the Earth and Planetary Sciences Department.

Pore waters from the top six inches of sediment core collected from the San Juan Generating Station reservoir were collected and analyzed for inorganic elements.

Pore waters from the top six inches of sediment core collected from the San Juan Generating Station reservoir were collected and analyzed for inorganic elements.

As part of the Navajo-Gallup Water Supply Project, the Bureau of Reclamation was tasked with design and construction of infrastructure to treat and deliver potable water to the communities of Navajo Nation, parts of the Jicarilla Apache Nation, and City of Gallup. The Bureau of Reclamation has been evaluating the Public Service Company of New Mexico's (PNM) San Juan Generating Station (SJGS) reservoir as a possible water storage and sediment settling basin for the Navajo-Gallup Water Supply Project. The U.S. Geological Survey (USGS), in cooperation with the Bureau of Reclamation, was tasked with collecting reservoir sediment cores and pore water from SJGS reservoir. This data release contains reservoir sediment organic chemistry results.

As part of the Navajo-Gallup Water Supply Project, the Bureau of Reclamation was tasked with design and construction of infrastructure to treat and deliver potable water to the communities of Navajo Nation, parts of the Jicarilla Apache Nation, and City of Gallup. The Bureau of Reclamation has been evaluating the Public Service Company of New Mexico's (PNM) San Juan Generating Station (SJGS) reservoir as a possible water storage and sediment settling basin for the Navajo-Gallup Water Supply Project. The U.S. Geological Survey (USGS), in cooperation with the Bureau of Reclamation, was tasked with collecting reservoir sediment cores and pore water from SJGS reservoir. This data release contains reservoir sediment organic chemistry results.

This study was done because elevated concentrations of metals including aluminum, arsenic, and lead were identified by Navajo Nation EPA staff in the San Juan River from below the Navajo Dam, through the Navajo Nation to Mexican Hat, Utah in the Four Corners Region of the United States (Colorado, Arizona, New Mexico, Utah). An interdisciplinary team applied approaches and principles of geology, geochemistry, geomorphology, hydrology, and statistics to gain a better understanding of the tributaries supplying the source(s) of metals to the San Juan River. Water samples were collected in single-siphon samples and by grab sample at 59 ephemeral and perennial tributaries to the San Juan River in 2021 and 2022. Eighteen surface water sites along the San Juan River were sampled as grab samples in 2021 and 2022 and fifteen sites along the San Juan River were sampled by equal width increment and composited in a churn during a baseflow synoptic sampling campaign in February 2021. A total of 765 unfiltered and 282 filtered samples were analyzed for major and trace cations. All samples were analyzed through the USGS Analytical Chemistry Laboratory in Denver, Colorado (Taggart, 2022; USGS, 2023 Method 37).

Elevated concentrations of metals including aluminum, arsenic, and lead were identified by Navajo Nation Environmental Protection Agency staff in the San Juan River from below the Navajo Dam, through the Navajo Nation to Mexican Hat, Utah in the Four Corners Region of the United States (Colorado, Arizona, New Mexico, Utah). An interdisciplinary team applied approaches and principles of geology, geochemistry, geomorphology, hydrology, and statistics to gain a better understanding of the tributaries supplying the source(s) of metals to the San Juan River. Water samples that were filtered with 0.45 micron filters were collected in single-siphon samplers and by grab sample at 41 ephemeral and perennial tributaries to the San Juan River in 2021 and 2022. Eighteen surface water sites along the San Juan River were sampled as grab samples in 2021 and 2022. Samples were chosen randomly for filtration to compare to unfiltered sample results. The samples were analyzed for major and trace cations by inductively coupled plasma emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS) at the US Geological Survey Analytical Chemistry Laboratory in Denver, Colorado. A sub-set of samples includes data for pH and alkalinity as calcium carbonate. A total of 282 filtered samples were collected.

Elevated concentrations of metals including aluminum, arsenic, and lead were identified by Navajo Nation Environmental Protection Agency staff in the San Juan River from below the Navajo Dam, through the Navajo Nation to Mexican Hat, Utah in the Four Corners Region of the United States (Colorado, Arizona, New Mexico, Utah). An interdisciplinary team applied approaches and principles of geology, geochemistry, geomorphology, hydrology, and statistics to gain a better understanding of the tributaries supplying the source(s) of metals to the San Juan River. Water samples that were filtered with 0.45 micron filters were collected in single-siphon samplers and by grab sample at 41 ephemeral and perennial tributaries to the San Juan River in 2021 and 2022. Eighteen surface water sites along the San Juan River were sampled as grab samples in 2021 and 2022. Samples were chosen randomly for filtration to compare to unfiltered sample results. The samples were analyzed for major and trace cations by inductively coupled plasma emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS) at the US Geological Survey Analytical Chemistry Laboratory in Denver, Colorado. A sub-set of samples includes data for pH and alkalinity as calcium carbonate. A total of 282 filtered samples were collected.

Elevated concentrations of metals including aluminum, arsenic, and lead were identified by Navajo Nation Environmental Protection Agency staff in the San Juan River from below the Navajo Dam, through the Navajo Nation to Mexican Hat, Utah in the Four Corners Region of the United States (Colorado, Arizona, New Mexico, Utah). An interdisciplinary team applied approaches and principles of geology, geochemistry, geomorphology, hydrology, and statistics to gain a better understanding of the tributaries supplying the source(s) of metals to the San Juan River. 15 sites along the San Juan River were sampled by the equal width increment method and composited in a churn during a baseflow synoptic sampling campaign in February 2021 (USGS, 2018). Unfiltered water samples were collected in single-siphon samples and by grab sample at 59 ephemeral and perennial tributaries to the San Juan River in 2021 and 2022. Eighteen surface water sites along the San Juan River were sampled as grab samples in 2021 and 2022. The samples were analyzed for major and trace cations by inductively coupled plasma emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS) at the US Geological Survey Analytical Chemistry Laboratory in Denver, Colorado. A total of 765 unfiltered samples were analyzed.

Elevated concentrations of metals including aluminum, arsenic, and lead were identified by Navajo Nation Environmental Protection Agency staff in the San Juan River from below the Navajo Dam, through the Navajo Nation to Mexican Hat, Utah in the Four Corners Region of the United States (Colorado, Arizona, New Mexico, Utah). An interdisciplinary team applied approaches and principles of geology, geochemistry, geomorphology, hydrology, and statistics to gain a better understanding of the tributaries supplying the source(s) of metals to the San Juan River. 15 sites along the San Juan River were sampled by the equal width increment method and composited in a churn during a baseflow synoptic sampling campaign in February 2021 (USGS, 2018). Unfiltered water samples were collected in single-siphon samples and by grab sample at 59 ephemeral and perennial tributaries to the San Juan River in 2021 and 2022. Eighteen surface water sites along the San Juan River were sampled as grab samples in 2021 and 2022. The samples were analyzed for major and trace cations by inductively coupled plasma emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS) at the US Geological Survey Analytical Chemistry Laboratory in Denver, Colorado. A total of 765 unfiltered samples were analyzed.