Trees and shrubs in the Corrales Bosque Preserve are being cut down and turned into wood chips by the Fire Department in a controversial project along the base of the levee. The project was approved by the Village Council over warnings from the Bosque Advisory Commission. As originally presented, the removal of vegetation was supposed to spare native species. But, as nearly always happens when chainsaws are switched on in the preserve, vegetation that should have been unharmed was taken down.

In theory, removal of trees and other vegetation growing along the “toe” (or base) of the levee along its east side was said to be necessary to protect it and allow better access for fire department equipment. (See Corrales Comment Vol.XXXX No.17 October 23, 2021 “Bosque Preserve Clearing Along Levee Gets OK.”)

Clearing and wood-chipping began Saturday, February 26, in the first stage between Dixon Road and Romero Road. The clearing is expected to continue for the entire length of the levee, from Alameda Bridge on the south to the Rio Rancho boundary on the north.

The Bosque Advisory Commission had won concessions from the Middle Rio Grande Conservancy District, which owns or manages the riparian property, to avoid removing native species such as New Mexico Olive trees, an important food for birds and other fauna.

Last year, the Audubon Society formally sought such protections.

The Village was asked to conduct a “scientifically informed assessment of the fire risk” in the Bosque Preserve before approving a project that would remove much of the vegetation along the east side of the levee.

The Audubon Society, which designated the Corrales Bosque Preserve as an “important bird area” in 2014,  weighed in on the proposal to eliminate vegetation along the east side of the levee in a November 9, 2021 letter to the mayor and Village Council.

The Central N.M. Audubon Society asked the Village to reconsider its preliminary approval for the proposal by the Corrales Fire Department and the N.M. Forestry Division that would begin before spring.

The letter requested “reconsideration of the plans to clear trees along the Corrales Bosque levee detailed in the “Wildland/Urban Interface Hazardous Fuels Reduction” proposal. We find the proposal’s fire danger estimate of the vegetation along the levee to be unsupported scientifically and likely exaggerated.

“It is also our position that the habitat and ecological value of the trees targeted to be cleared, and the project area’s designation of this section of Corrales bosque as an Important Bird Area , has been underestimated.”

In the letter, the regional society raised many of the same issues presented by members of the Corrales Bosque Advisory Commission last month. The letter was signed by Perrianne Houghton, president of the Central New Mexico Audubon Society.

“From the proposal, it is unclear whether the primary intent of clearing trees extending from the toe of the levee, is to create a clear passage for emergency vehicles in case of a Bosque fire, or whether the primary motivation is to reduce potential fuel for a fire. If the former, then removing native trees —and particularly Coyote Willows— growing in and along the ditch banks, is clearly unnecessary and should be avoided, as they do not impede the passage of vehicles along the levee.

“It defies logic, that in the face of this epic drought, Corrales is allowing precious native New Mexico olive to be cut by the many hundreds along the base of the east side of the levee.  It is fire-resistant, provides food, and many are 30 years old or more and could withstand the warming climate.  Who will suffer?  The animals, of course, especially birds, who are being faced with habitat loss at every point of their migration.  We will be losers too as our world is less varied and interesting with fewer critters in it.” 

“If the latter, then we ask, before going forward with clearing the levees, the Village of Corrales make a scientifically informed assessment of the fire risk posed by native riparian trees (including Rio Grande Cottonwoods, New Mexico Olives, and Coyote and Goodings Willows) that are vitally connected to a continuous water source (in this case, the irrigation ditch that flows parallel to the levee year round).”

After a presentation on  the proposal given by Fire Chief Anthony Martinez, the council voted to let the project move ahead.

In the November 9 letter, the Central New Mexico Audubon Society (CNMAS) and Audubon Southwest (ASW) asked for more transparency in decisions about clearing vegetation in the preserve given the presentation to the council September 14, 2021. 

“While CNMAS and ASW recognize the increased fire risk posed by a hotter, drier climate and understand that clearing vegetation and cutting trees can be an essential fire preventive, we urge you to take a scientific approach to management of this area, that accurately assesses the fire dangers posed by native riparian vegetation and trees connected to a continuously flowing water source.”

The two Audubon organizations said they support much of the assessment produced by the bosque advisory commission. “This report uses peer-reviewed, scientific studies to evaluate the role trees play in supporting native wildlife and the overall ecology of the Corrales Bosque, along the levee. We endorse the following CBAC recommendations:

“•  We do not see the necessity of thinning the entire 20-foot strip. Thinning should be accomplished in areas where fire access is most necessary, rather than thinning within a uniform width along the entire levee.”

“•  All small Elms, Tamarisk, and Tree of Heaven should be removed, when possible, without damaging stands of New Mexico Olive and willows.”

“•  Healthy Russian Olive trees within the 15-foot strip should be left in all areas where they don’t interfere with access needed for fire personnel… dead Russian Olive may be removed within the 15-foot strip where access or levee maintenance is required.”

“Most significantly, we endorse what the CBAC refers to as their most important recommendation, which is for transparency in the activities of the MRGCD and Chief Martinez in what they ‘intend to do, and where’ as part of Wildland/Urban Interface Hazardous Fuels Reduction projects.

“In addition to supporting the above CBAC recommendations, CNMAS and ASW would like to point out that between 217 and 238 species of birds have been recorded at various birding hotspots along the length of the Corrales Bosque, demonstrating it to be an extremely important New Mexico bird habitat:

“•  While stands of ‘willows’ are mentioned generally within the second bulleted item above, we want to specify this refers to Coyote Willows (Salix exigua) and emphasize this should be among the species (along with Cottonwoods and New Mexico Olives) that are the highest priority to preserve due to their high ecological and habitat value. Coyote Willow stands provide nesting sites for a variety of native songbirds, for example Common Yellowthroats, Yellow-Breasted Chats, Blue Grosbeaks, and Spotted Towhees, as well as a potential habitat for the endangered Southwestern Willow Flycatcher. This diversity of native plant and bird species reflects the designation of this section of Corrales bosque as an Important Bird Area (IBA)  by New Mexico Audubon Society (currently Audubon Southwest) in May 2014.

“•  From the proposal, it is unclear whether the primary intent of clearing trees extending from the toe of the levee, is to create a clear passage for emergency vehicles in case of a bosque fire, or whether the primary motivation is to reduce potential fuel for a fire. If the former, then removing native trees  —and particularly Coyote Willows—  growing in and along the ditch banks, is clearly unnecessary and should be avoided, as they do not impede the passage of vehicles along the levee.

“If the latter, then we ask, before going forward with clearing the levees, the Village of Corrales make a scientifically informed assessment of the fire risk posed by native riparian trees (including Rio Grande Cottonwoods, New Mexico Olives, and Coyote and Goodings Willows) that are vitally connected to a continuous water source (in this case, the irrigation ditch that flows parallel to the levee year round).

“Historically, bosque fires only increased in frequency and severity once trees were disconnected from the river, due to dredging and channelization that effectively stopped annual flooding. If the aforementioned native trees are associated with the irrigation ditch, it is likely the fire risk they pose is minimal.

“We would finally draw your attention to the vital role of shade trees and vegetation in combating the impacts of  climate change by helping to maintain lower stream temperatures, and reduce evaporation:

“•  Shade from trees and other vegetation along the irrigation ditch helps to maintain lower water temperatures, which results in less evaporation. Climate change and drought make maintaining lower ditch temperatures and minimizing evaporation increasingly crucial. As the study ‘Effects of Riparian Management Strategies on Stream Temperature Science Review Team Temperature Subgroup’ points out, ‘the most efficient method to maintain low stream temperatures is to reduce heat loading from solar radiation. Shade prevents stream warming by reducing inputs of heat energy from solar radiation’ (Leinenbach, McFadden, and Torgersen).

“ Greater evaporation from the irrigation ditch would decrease water for farmers and water available to return to the river channel downstream.

“•  As climate change continues to reduce and periodically stop water flow within the river channel, many of the native riparian trees growing near the river will likely struggle to survive. This makes the preservation of habitat along irrigation ditches, including trees growing near the levee, increasingly crucial. Even as the Rio Grande has dried for many months each year in the Lower Rio Grande, irrigation ditches have continued to flow.

“If irrigation ditches become the only continuously flowing water through the Middle Rio Grande, then the future distribution and abundance of native riparian plants and trees —as well as the survival of the native animal species that depend on them— will be increasingly dependent upon our ability to preserve and even encourage their growth along irrigation ditches and levees.”

The Village Council gave a go-ahead to Fire Chief Anthony Martinez and the Middle Rio Grande Conservancy District at its October 10, 2021 meeting where Martinez and MRGCD Planner Yasmeen Najmi convinced the mayor and all councillors to let the clearing project proceed. No timetable was given when work would begin, although it would have to cease, or pause, by April 15  to comply with the federal Migratory Bird Act.

If the plan goes ahead as described in October, all along the entire length of the levee, non-native trees and other vegetation would be cut and removed at the edge of levee on its east, or river, side. According to Najmi, that is necessary to maintain the levee, although it was not stated what kind of maintenance would be needed that could not be done from the top of the levee.

However, she referred to retaining federal certification of the levee’s integrity, a concern raised 12 years ago the last time the Corps of Engineers and MRGCD proposed clearing trees from the toe of the levee.

Back then, the Corps’ Fritz Blake, since retired, explained that the proposed clearing probably would not be required after all because the federal requirement was an over-reaction to concerns about levees around the nation in the aftermath of Hurricane Katrina. (See Corrales Comment Vol.XXIX No.3 March 20, 2010 “Corrales Monitors Corps’ Research on Levee.”)

The 2010 project was to have removed essentially all vegetation within 15 feet of the levee.

“Initially,when the project was presented in September, the native trees, including New Mexico olive, were to be left alone,” the Bosque Commissioner Joan Hashimoto pointed out. “When the CBAC asked for more time to try to complete an analysis of the tree loss that the project would cause and had to generate a report by October 1, the project scope changed.  When these new guidelines came out before the October 12 council meeting, they were worse than the initial project because they included natives clearing. I’m unsure what prompted that. 

“The unanswered question is why does the MRGCD want to do this now?  The levee has been maintained as it has been for at least 20 years,” Hashimoto said. 

“We’ve heard answers that it can't be maintained only from the top anymore, and that there are increased risks of flood events. Now they are being backed up by the U.S. Army Corps of Engineers on this. This is a change in position as in a stakeholders meeting at the MRGCD in March 2018, the Corps did not recommend the clearing.

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