Village seeks change in cold water designation

• Cool water designation sought

Naturally occurring conditions prevent the towns of Ruidoso and Ruidoso Downs, which partner in a regional wastewater treatment plant that discharges into the Rio Ruidoso, from attaining cold water aquatic life use in the lower Ruidoso River and upper Rio Hondo, an expert concluded in his draft study prepared for the New Mexico Surface Water Quality Bureau.

That inability to meet new strict standards is tied primarily to high summer water temperatures attributed to warm air temperatures; dissolved oxygen conditions that often do not meet cold water criteria, because of the combination of warm temperatures and low atmospheric pressures that occur at relatively high elevation; and a lack of reproducing populations of fish species that depend on cold water, Jim Good with Environmental Science Associates stated in the study.

He reached that conclusion in part by comparing the river to the Mimbres River, a reference stream in the same ecoregion with a relatively undisturbed watershed that has similar elevations and geomorphology, physical features related to geology. That comparison supported the conclusion “that problems with cold water aquatic life use attainment in the lower Rio Ruidoso and upper Rio Hondo occur naturally and are not due simply to anthropogenic (human pollution) disturbances.”

The draft recommends changes to the segment boundaries and aquatic life use designations in the New Mexico Water Quality Standards.

The decision of the state about the designation of either cold or cool water for aquatic life will impact the ultimate cost to customers of the plant for the treatment of the discharge to attain water quality standards.

Acting as the Joint Use Board that governs the treatment plant, officials with Ruidoso, which operates the plant, and Ruidoso Downs opened a public comment period on the draft Use Attainability Analysis and proposed amendments to the surface water quality standards (20.6.4. NMAC) for those two areas of the river system in Lincoln County.

A public meeting also is scheduled for 6 p.m. to 7:30 p.m., Oct .11, to present and discuss the draft UAA, including the proposed water quality standards amendment, and to provide a forum for interested parties to ask questions. The meeting will be in council chambers at village hall, 313 Cree Meadows Drive.

As required by the federal Clean Water Act and the New Mexico Water Quality Act, the state established water quality standards for its surface waters, and those standards identify the water quality goals for a water body, or portion thereof, by designating the use or uses of the water and by setting criteria that protect those designated uses. The Clean Water Act requires a state to adopt the highest attainable use in designating aquatic life uses for any body of water. To remove or change those criteria, a state or tribe must conduct an UAA demonstrating that the use is not attainable, because of one or more of six factors, and determining the highest use attainable, the study summary states.

A UAA is a scientific study that assesses the factors affecting the attainment of a designated use. Good conducted the study for the lower Rio Ruidoso and upper Rio Hondo in Lincoln County. The draft UAA along with the proposed water quality standards amendment under 20.6.4 NMAC, are available on the Surface Water Quality Bureau website at  https://www.env.nm.gov/surface-water-quality/wqs/.

In his summary, Good wrote that a change in elevation, vegetation and hydrology occurs at about the Hollywood station, the border between the city of Ruidoso Downs and the village of Ruidoso.

“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 (underground water storage/stream),” he wrote. “The transition from defined incised canyons to a widening meandering active channel that may be occupied by flood waters during snowmelt and major stream 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. Those natural transitions in geology, elevation, river geomorphology, hydrology, higher ambient air temperatures and reduced shade are the primary factors limiting the downstream extent of cold water aquatic life.”

Upstream from the Hollywood gauging station, the state applies a special trout water regulation in managing a brown trout population that is maintained through natural reproduction, he noted.

“It appears that spring-fed cold water and/or refugia (organisms able to live in less than desirable conditions) exist in the upper Rio Ruidoso that may support a reproducing population of brown trout, demonstrating that the cold water ALU is attainable above Hollywood, despite occurrences of high air temperatures,” he wrote.

Based on the UAA, he recommended changing 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 (U.S. Geological Survey) gauging station at Hollywood.”

The second recommendation was to delete from the 20.6.4-208 segment the Rio Ruidoso downstream of the U.S. 70 bridge near Seeping Springs lakes and perennial reaches of the Rio Hondo upstream from Bonney Canyon.”

The third is to establish a new segment 20.6.4-230 that consists of the Rio Ruidoso downstream of the Hollywood stream gauge and perennial reaches of the Rio Hondo upstream from Bonney Canyon. The new segment would have a cool water ALU designation.

The different segments of the river system are designated on a map included in the study.

The comment period for the proposal begins Sept. 20, and closes at 5 p.m., Oct. 20. Comments for inclusion in the public record must be submitted in writing to Jim Good at Environmental Science Associates, 5309 Shilshole Ave. NW, Suite 200, Seattle, Wash., 98107; or by e-mail: jgood@esassoc.com.