Final Draft AQUATIC LIFE USES FOR THE LOWER RIO RUIDOSO AND UPPER RIO HONDO IN NEW MEXICO Use Attainability Analysis Prepared for August 2017 Village of Ruidoso and City of Ruidoso Downs Regional Wastewater Treatment Plant Joint Use Board Final Draft AQUATIC LIFE USES FOR THE LOWER RIO RUIDOSO AND UPPER RIO HONDO IN NEW MEXICO Use Attainability Analysis Prepared for Village of Ruidoso and City of Ruidoso Downs Regional Wastewater Treatment Plant Joint Use Board 313 Cree Meadow Drive Ruidoso, New Mexico 88345 Prepared by Jim Good Principal Associate ESA Project Number D160243.00 5309 Shilshole Avenue, NW Suite 200 Seattle, WA 98107 206.789.9658 www.esassoc.com Irvine Sacramento Los Angeles San Diego Oakland San Francisco Orlando Santa Monica Pasadena Seattle Petaluma Tampa Portland Woodland Hills OUR COMMITMENT TO SUSTAINABILITY | ESA helps a variety of public and private sector clients plan and prepare for climate change and emerging regulations that limit GHG emissions. ESA is a registered assessor with the California Climate Action Registry, a Climate Leader, and founding reporter for the Climate Registry. ESA is also a corporate member of the U.S. Green Building Council and the Business Council on Climate Change (BC3). Internally, ESA has adopted a Sustainability Vision and Policy Statement and a plan to reduce waste and energy within our operations. This document was produced using recycled paper. SUMMARY This Use Attainability Analysis (UAA) was conducted to (1) determine factors affecting the attainment of aquatic life uses (ALUs), (2) identify the most protective attainable aquatic life uses for the lower Rio Ruidoso and upper Rio Hondo, and (3) perform a data-driven evaluation of current or existing uses. From the analysis, the Village of Ruidoso and City of Ruidoso Downs (Ruidoso) proposes to refine the currently designated uses based on a weight-of-evidence analysis. The Clean Water Act (CWA) §101(a)(2) and 20.6.4.6 NMAC of the WQS require that, wherever attainable, water quality shall provide for the protection and propagation of fish, shellfish and wildlife and for recreation in and on the water. States are required to adopt the highest attainable use in designating the ALU for any water body. In order to remove a §101(a)(2) use or change it to one with less stringent criteria, a state or tribe must conduct a UAA (1) demonstrating that the use is not attainable due to one or more of the six factors listed in 40 CFR 131.10(g), and (2) determining the most protective aquatic life and contact uses that are attainable. This UAA focuses on Factor 1 in assessing whether the natural ambient air temperatures (i.e., naturally occurring thermal pollution) and other physical conditions prevent the attainment of the designated coldwater ALU (40 CFR 131.10[g][1]). In Segment 20.6.4.209 the Rio Ruidoso originates in the high-elevation Rocky Mountain subalpine forests and encounters geomorphic and hydrologic changes as it flows eastward into Segment 20.6.4.208 where, with the Rio Bonito, it forms the Rio Hondo, passing through three ecoregions before entering the Southern New Mexico dissected plains. The variations in geomorphology along this gradient produce significant changes in hydrology, riparian vegetation, and water quality. The transition from Rocky Mountain Conifer Forests to Madrean Lower Montane Woodlands occurs near the Ruidoso fault zone and in the vicinity of the Hollywood, New Mexico, stream gauging station. This is also the area where the canyon opens into a broad floodplain with less shade from forested hillslopes, and the hydrology changes from a gaining to a losing stream where some of the surface flow enters an alluvial aquifer. The transition from defined incised canyons to a widening meandering active channel that may be occupied by flood waters during snowmelt and major storm events causes changes to the flow path in the middle and lower reaches of the Rio Ruidoso, limiting persistent riparian shading in some parts of the active channel. These natural transitions in geology, elevation, river geomorphology, hydrology, higher ambient air temperatures and reduced shade are the primary factors limiting the downstream extent of coldwater aquatic life. Air-water temperature modeling and hourly temperature monitoring data suggest that coldwater aquatic life use is not attainable throughout much of the Rio Ruidoso, even in the Rocky Mountain Conifer Forest ecoregion. However, upstream from Hollywood the State applies a Special Trout Water regulation in managing a brown trout population that is maintained through natural reproduction. It appears that spring- fed cold water and/or refugia exist in the upper Rio Ruidoso that may support a reproducing population of brown trout, demonstrating that the coldwater ALU is attainable above Hollywood, despite occurrences of high air temperatures. Fish survey data, including surveys from various periods between 1916 and 2015, Aquatic Life Uses For the Lower Rio Ruidoso and Upper Rio Hondo in New Mexico i ESA / D160243.00 Use Attainability Analysis August 2017 Summary indicate that reproducing populations of coldwater species are not present in the lower Rio Ruidoso below Hollywood or in the Rio Hondo. Because documented anthropogenic stressors may influence lower Rio Ruidoso and upper Rio Hondo water temperatures and the attainability of a coldwater ALU, temperature analyses and fisheries data were also compared for the lower Mimbres River, a relatively undisturbed reference stream having similar latitude, elevations, and ecoregions. These comparisons help show that naturally occurring warm air temperatures would prevent the attainment of a coldwater ALU in the lower Rio Ruidoso and upper Rio Hondo regardless of anthropogenic stressors. In addition to high ambient air temperatures resulting in high water temperatures, modeling of dissolved oxygen (DO) solubility shows that the minimum DO criterion for coldwater (6.0 mg/L) is not consistently attainable due to physical factors (i.e., high elevation, atmospheric pressure) and the natural range of water temperatures. The DO solubility modeling was performed using data for the lower Mimbres River, considered to be representative of the water temperature and DO conditions that might be attainable in the lower Rio Ruidoso and upper Rio Hondo in the absence of extensive anthropogenic stressors. DO solubility modeling for the lower Rio Ruidoso using similar water temperatures, elevations and atmospheric pressures also showed that the minimum DO criterion for coldwater was not consistently attainable. As the Rio Ruidoso transitions from the Rocky Mountain Conifer Forests to the Madrean Lower Montane Woodlands ecoregion, stream shading is diminished and both measured and modeled water temperatures increased. Downstream from the Rio Ruidoso and Rio Bonito confluence, the Rio Hondo flows through the Southern New Mexico Dissected Plains ecoregion characterized by sparse vegetative cover and an increasingly warm climate. Air-water temperature correlation modeling indicates that a coldwater ALU designation is even less attainable in the Rio Hondo than the lower Rio Ruidoso. The preponderance of evidence from geomorphic and hydrologic changes, ecoregion information, thermograph and sonde measurements, AWTC modeling, oxygen solubility modeling, and fish surveys indicates that the coldwater ALU is not attainable in the Rio Ruidoso below Hollywood; however, a coolwater designation is appropriate and attainable for the remainder of the river downstream from Hollywood to the Rio Bonito confluence. The presence of several coolwater species in each historical fish survey suggests that it is appropriate to extend a coolwater ALU designation downstream from the lower Rio Ruidoso through the Rio Hondo in Segment 20.6.4-208. Because Segment 20.6.4.208 also includes several high-elevation streams where a coldwater ALU may be attainable (perennial reaches of the Rio Peñasco above state highway 24 near Dunken, perennial reaches of the Rio Bonito downstream from state highway 48 [near Angus], and perennial reaches of Agua Chiquita), it is proposed that the lower Rio Ruidoso and upper Rio Hondo are deleted from Segment 20.6.4.208 and a new segment is established for these warmer stream segments. In summary, based on this UAA it is recommended to: 1. Change the upper Rio Ruidoso in Segment 20.6.4-209 from perennial reaches of the Rio Ruidoso and its tributaries “upstream of the U.S. 70 Bridge” to “upstream of the USGS gauging station at Hollywood, New Mexico”; 2. Delete from Segment 20.6.4-208 the Rio Ruidoso downstream of the U.S. highway 70 bridge near Seeping Springs lakes, and perennial reaches of the Rio Hondo upstream from Bonney canyon; Aquatic Life Uses For the Lower Rio Ruidoso and Upper Rio Hondo in New Mexico ii ESA / D160243.00 Use Attainability Analysis August 2017 Summary 3. Establish a new Segment 20.6.4-230 that consists of the Rio Ruidoso downstream of the Hollywood, New Mexico stream gauging station, and perennial reaches of the Rio Hondo upstream from Bonney canyon. This new segment will have a coolwater ALU designation. A weight-of-evidence approach was used to determine the attainable ALU, considering New Mexico’s ecoregional setting and watershed geomorphology, and analyzing recent water temperature monitoring data, air-water temperature correlations, dissolved oxygen solubility, and recent and historical surveys of fish communities. The lower Mimbres River was selected for reference site evaluations and similar analyses were compared