NS 2023 Annual Report For EPA

• IBM Index Class Name: Hydrology
• Doc Date: 8/28/2025
• Archive: No

Natural Soda LLC 2023 Project Status Report & Annual Plan of Development
27 January 2024

5.1.2. Storage and Evaporation Ponds
The NS storage and evaporation ponds have a secondary liner and are constructed to
collect and direct any condensation or leakage to tubes for removal. Pond information is
reported on a monthly basis. No changes occurred to the evaporations ponds in 2023,
routine maintenance and monitoring continued throughout the year.
5.1.3. Potentiometric Surface Maps (Confidential)
Using groundwater potentiometric elevations from NS groundwater monitoring wells and
other NS wells, A-Groove and B-Groove Aquifer potentiometric surface maps have been
plotted and have been included with this report in Appendix B (Confidential).
5.1.4. Stream Gauging Stations
NS contracts with the USGS to monitor surface waters for water quality and quantity.
Monitoring was performed upstream and downstream relative to the NS mining
operations and with respect to Yellow Creek and Piceance Creek at four existing
stations with extensive historical data. Historical stream gauging data is reported in this
document and discharge data is complete through the 2023 water year (WY) (October
2022 – September 2023).
The USGS surface water data are available to the public from the USGS web site at
http://co.water.usgs.gov. Table 7 and Table 8 summarize key 2023 WY data for surface
water near the NS site. Data reported in Table 7 and Table 8 is compiled from the
USGS web site. The Specific Conductance and Temperature data included in the
tables were generated by using USGS lab test results for each stream reported on the
USGS web site during the 2023 WY.
The USGS notes in the 2022 and 2023 year end water reports that the 6200 (Piceance
Creek below Ryan Gulch) has diversions for irrigation upstream of the monitor station.
The 6222 (Piceance Creek at White River) has diversions for irrigation of approximately
5,500 acres upstream from the monitor station. The 6255 (Yellow Creek near White
River) has diversions to irrigate approximately 300 acres upstream from the monitor
station. The 6242 (Corral Gulch near Rangely) which historically has been a low flow
stream is not reported as having any diversions upstream from the monitoring station.
The 2023 WY discharge (cfs) data in this area indicated an increase in average stream
discharge levels for the 6242 Corral Gulch, 6255 Yellow Creek, 6200 and 6222
Piceance Creek streams. 2023 discharge was above the average Period of Record
(PR) historic levels, but did not reach the maximum discharge as seen in the 1984,
1985 and 1986 WY’s. The 2011 WY was the last time similar discharge values to 2023
WY were recorded in the streams of interest.