The Village of Corrales has been 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, has weighed in on the proposal to eliminate vegetation along the east side of the levee in a November 9 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 could 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.
“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. (See Corrales Comment Vol.XXXX No.17 October 23, 2021 “Bosque Preserve Clearing Along Levee Gets OK.”)
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. National Audubon Society | Audubon Southwest 3131 S. Central Avenue | Phoenix, AZ 85040/
“• 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 help 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.
“To summarize, CNMAS and ASW request 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. CNMAS and ASW support several recommendations of the CBAC. In addition, we agree with the importance of transparency in the activities of the MRGCD and Chief Martinez in their objectives for the Wildland/Urban Interface Hazardous Fuels Reduction projects.
“CNMAS and ASW thank you for your consideration of this most important issue. We are available and willing to help continue the conversation and look forward to working closely with you for the betterment of our natural surroundings.”
The Village Council gave a go-ahead to Fire Chief Anthony Martinez and the Middle Rio Grande Conservancy District at its October 10 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.
In late November, funding for the clearing project had not been made available.
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 11 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.
Blake said in an interview February 2, 2009 that trees along the Corrales levee might not need to be removed after all.
He said the new levee safety criterion of a 15-foot, tree-free buffer at the sides of the levee was being resisted elsewhere around the United States as well.
“We understand that this is a difficult situation for the Conservancy District and for the Village of Corrales, and we will continue to work with both to get it resolved. Our number one priority is to ensure the safety of the levee. But we’re not quite convinced yet that taking out a 15-foot swath of trees is the way to solve the problem.” Blade said.
Most of the trees of concern existed when the Corps rebuilt the levee in 1996-97. The design of the levee at that time did not require those trees’ removal. Even so, nearly 2,000 trees were removed when the levee work was done, but those that were retained on the river side were considered no threat to the levee. At that time, trees could be no closer than three feet to the toe of the levee.
Besides, Blake noted in 2009, if they started removing those trees, it might be determined a year later that it wasn’t really necessary. “It’s possible that a year from now, our technical people might say, ‘Gee, you don’t really need to do that.’”
When the current Corrales levee was dedicated after being built in 1996-97, it was touted as the best in the United States. “This is one of the best, if not the best, levee in the nation,” said Don Lopez, representing the State Engineer’s office and the Interstate Stream Commission.
At the October 12, 2021 Village Council meeting, members of the Corrales Bosque Advisory Commission tried to convince the mayor and council not to give the fire chief and the MRGCD carte blanche to take out all non-native vegetation along the levee. They especially urged that Russian olive trees be retained as a crucial source of food for birds in winter.
Joan Hashimoto, chairperson for the advisory commission, warned that the wholesale removal of trees and thicket next to the levee could actually jeopardize its integrity. Bike tires, hiking boots and horse hooves predictably would cut new paths down the side of the levee channeling increased erosion.
And, she said, the project will “allow bikes, people and dogs to find a new place to reach wildlife. The native shrub and tree removal combined with the Clear Ditch drying, and also the river being almost non-existent, is like a triple-whammy for the animals of our nature preserve.”
Hashimoto pointed out that “levee toe thinning will cut a huge number of living trees and destroy valuable habitat, while a massive dead-and-down fuel load problem exists and indeed gets larger every year with cottonwood’ auto-pruning branches and trees dying.
“I understand regulations. Maintaining the levee is important. Ever since the current levee was constructed over 20 years ago, the east slope has been maintained from the levee road. Although the levee toe is not in strict compliance with regulations, which has been the case and well-known since its construction, the Army Corps of Engineers which has done the levee surveys, has said that the toe vegetation non-compliance would not affect future levee eligibility for federal funding.”
She insisted that the Corrales bird study corridors, or transects, not be destroyed by clearing next to the levee, pointing out that research in those corridors has been funded by the Corps of Engineers and Hawks Aloft, Inc. “It’s important to preserve the transects.”
She concluded by urging “Do thinning where it’s indicated, not monolithic clearing and thinning.”
Another bosque advisory commissioner, Joan Morrison, said she was discouraged by council’s approval of the Fire Department’s plan.
“This proposed clearing of all trees and shrubs including native New Mexico olive is horrendous, and although they say it is only three percent of the total bosque, my walk today revealed that it is likely the most important three percent.
“There isn’t much New Mexico olive down in the middle of the bosque at all. And you can bet that clearing a 10-foot strip (10 feet isn’t really all that wide, barely enough for any big machinery) will likely turn into a strip much wider.”
At the council meeting, Morrison said “Last month, I and other CBAC members presented our concerns regarding the proposed Invasive Species Clearing Project Work Plan. Since our commission’s response to any work in the bosque will be science-based, we subsequently presented to you, on October three, our report in which we outlined these concerns, presented data that our members had collected on the number of trees potentially affected by this project, and offered recommendations and to collaborate with the Fire Department and Conservancy on this work plan.
“In reading the work plan submitted to you for tonight’s meeting, I was dismayed to discover that not only were none of our concerns or recommendations considered or even acknowledged, but that in some ways this new work plan proposes to be even more harmful to our bosque.
“May I remind council members that the Corrales Bosque Preserve is designated as a protected area and an Important Bird Area, and the Village of Corrales is tasked with maintaining it as a natural area and wildlife preserve. Council has also approved the Bosque Management Guidelines which are meant to foster data-driven decisions and collaboration with the goal of protecting and preserving a variety of habitats in our bosque.
One concern about this proposed work continues to involve process: the CBAC was not informed of the initial proposal until three days before the September council meeting, CBAC members present and past who have extensive scientific background were not consulted or even informed, and our concerns were not considered in this new proposal despite our stated willingness to coordinate on this project with the Fire Department and the Conservancy.
“Our primary concerns remain the potential impacts to wildlife habitats from the proposed work.”
Morrison was critical that “No justification is given for the need to completely clear a 10-foot strip out from the toe along the entire length of the levee. In its over 20 years of existence, the levee has never required such vegetation clearance despite multiple inspections. The levee’s east slope has always been maintained from the levee road on the top, so why the need now for complete clearing out from the toe?
“During the September 23 field trip, Chief Martinez indicated that limited fire access pathways into the bosque could be cleared rather than clearing along the entire length of the levee. Thus we see no justification for complete clearing.
“Non-native vegetation within the ten feet should be cleared only at the points where access is needed into the bosque for fire equipment and personnel or where a specific levee maintenance activity is required. Large scale clearing of vegetation along the levee sides and out ten-20 feet from the toe will encourage people to make new paths down the levee sides, causing even more subsidence and erosion.
“There is an extensive amount of dead and down wood along the levee toe that has been left from former clearing projects. This material constitutes a large and dangerous fuel load. It is important that all cut trees and other dead and down material generated by this project and from previous projects within the 20-foot area from the levee toe should be removed out of the bosque. If left, this material only adds to this already large fuel load, increasing fire risk.”
Morrison is professor emerita of biology and environmental science at Trinity College in Hartford, Connecticut.
She emphasized that “Any clearing or thinning work in the bosque must be completed by the start of migratory songbird nesting season, April 15, 2022. However, some hawks and owls known to nest in the bosque begin nesting as early as February and March.
“If this work is to move forward such nests must be identified and appropriate buffers designated. Disturbance or destruction of these nests resulting from the project would be a violation of the federal Migratory Bird Treaty Act.
“Council members, Corrales is advertised as a village with a lovely and natural bosque, and people come here to enjoy it. Do we want to be known as the Village that cut down prime bosque habitat?
“If you are inclined to accept this proposed work plan, I request that you do so only with commitment to assign and be accountable for the following modifications:
- Leave all New Mexico olive untouched within the entire 20 feet from the levee toe.
- The Hawks Aloft transects should be left untouched by this project.
- Do not clear the entire ten-foot strip along the entire length of the levee but only where needed, at identified intervals where access into the bosque is required for fire equipment and personnel.
- Remove all cut trees and other dead and down wood generated by this project and others within the 20-foot area from the levee toe, and remove it out of the bosque.”
A former member of the advisory commission, ornithologist Janet Ruth, said the project should avoid taking out standing dead trees since such “snags” provide crucial opportunities for cavity-nesting birds.
“I would prefer to see those left standing except if they posed a real risk.”
Ruth’s submission to the Audubon Society resulted in its designation of the Corrales bosque as an “Important Bird Area” in 2014.