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HomeMy WebLinkAboutPublic Comments from William NashEvidence Memo: Risks & Considerations for Solar -PV Near Wetlands Purpose To summarize current scientific evidence on environmental impacts of solar -PV facilities — especially soil/water contamination, hydrology and microclimate shifts, and wildlife (notably waterbird) impacts — and highlight how these findings apply to solar proposals near sensitive wetland ecosystems. Key Evidence & Findings 1. Reduced biodiversity / altered wildlife communities — especially waterbirds • A recent global review, Assessing the Impact of Solar Farms on Waterbirds: A Literature Review of Ecological Interactions and Habitat Alterations (2025), notes that waterbirds are a "vital part of wetland ecosystems" but there is a "lack of information" regarding how solar infrastructure interacts with wetlands, microclimate, contaminants, and species interactions. MDPI • The review identifies potential threats: contaminated runoff/leachate, altered microclimate, land -use change, and altered habitat — all of which could affect waterbird behavior, reproduction, and survival. MDPI In a field study in southern California, Aquatic Habitat Bird Occurrences at Photovoltaic Solar Energy Development in Southern California, USA (2021) found that while some aquatic/bird species use PV sites, these sites did not replicate natural wetland value: bird diversity and abundance remained much higher at natural waterbody reference sites; the so-called "lake effect"—where birds mistake panels for water—was not clearly demonstrated. MDPI+1 • For water -surface (floating) PV installations, Floating photovoltaic systems homogenize the waterbird communities across subsidence wetlands in the North China Plain (2023) found that after FPV installation, the total number of waterbirds increased, but species diversity (Simpson's index, evenness) decreased. The community became more homogenized: diving birds decreased, while vegetation - gleaning and other guilds increased. PubMed+1 • Implication: Solar installations near wetlands may shift bird communities, reduce habitat suitability for wetland -specialist species, and degrade biodiversity even if "some" birds remain or are attracted. 2. Soil and Water Quality Risks — Contaminant Leaching & Chemical Exposure • A very recent study, Impact of photovoltaics on soil and water by metal(loid)s including technology critical elements: preliminary study (2025), analyzed soil and water near an older PV installation in Poland. The results detected elevated levels of several potentially hazardous elements (e.g., antimony, copper, tin, lead, gallium, indium, tellurium) in soils near PV arrays. The authors concluded that long-term PV use may contribute to trace -element pollution in soil, with potential risk to soils and associated hydrology or groundwater. Sprin erLink • The same study found that PV shading and layout caused spatial heterogeneity in soil moisture distribution — meaning some areas under panels became drier while gaps between panels were more moist. SSpringerLink Implication: In a wetland context—where soils, groundwater, and surface water are tightly interconnected — any leaching of heavy metals or technology-critical elements from aging or damaged panels could pose long-term contamination risk. Heterogeneous soil moisture could also disrupt natural hydrology, vegetation, or substrate conditions sensitive to water regime. 3. Hydrology & Microclimate Alteration — Changing Soil Moisture, Runoff, Groundwater Recharge • General plant-scale and ecosystem studies indicate that PV arrays often alter microclimate variables (soil moisture, temperature, wind, albedo) and hydrologic behavior (infiltration, runoff timing and distribution). The global synthesis Existing evidence on the effects of photovoltaic panels on biodiversity: a systematic map with critical appraisal of study validity (2023) found that while most research has occurred in deserts or drylands, some changes (especially in soil moisture and vegetation under panels) are documented even in non-arid settings. SpringerLink+1 • A more recent field study in a non-wetland but sensitive ecosystem — Environmental impacts of pastoral-integrated photovoltaic power plant in an alpine meadow on the eastern Tibetan Plateau (2025) — showed that PV installation significantly altered soil hydrothermal conditions: under-panel soil was colder and drier, gaps between panels were colder and moister; soil-moisture depletion rates changed, and snow/soil freeze-thaw period extended by –50 days. ACP • Other empirical work suggests that properly engineered solar farms can mitigate hydrologic disruption (runoff / erosion) with stormwater controls and vegetation management, but results are variable and depend heavily on design, slope, soil, vegetation, and climate. ScienceDaily+1 • Implication: Because wetlands depend on regular inundation, consistent groundwater recharge, and stable soil-moisture regimes, even relatively subtle shifts in hydrology/microclimate or soil moisture could degrade wetland functions — hydrology, vegetation, species habitat, flood absorption, etc. 4. Knowledge Gaps — Limited Wetland-Specific Research; Uncertain Long-Term Outcomes • The 2025 waterbird review explicitly notes the dearth of studies about solar installations in or adjacent to wetlands — nearly all empirical work to date concerns deserts, grasslands, agricultural lands, or non-wetland terrestrial ecosystems. MDPI+1 • The soil-water contamination study is "preliminary" and calls for more research across different geological and climatic zones. SpringerLink • Because of this limited data, projecting long-term, cumulative, or synergistic impacts (e.g. contamination + hydrology shifts + habitat fragmentation + species- specific vulnerability) for a coastal marsh or tidal wetland such as Los Cerritos remains speculative. • Implication: The lack of robust, wetland-specific science means that decision- makers and stakeholders should apply precaution, require conservative siting, robust baseline and long-term monitoring, and —where possible —avoid placing PV infrastructure in or adjacent to high-value wetlands. Conclusions & Recommendations (for Wetland -Adjacent Solar Projects) Based on the scientific evidence: Solar -PV is not a "benign" land use in or adjacent to wetlands. While PV helps reduce carbon emissions, in sensitive ecosystems like wetlands there are real and documented risks to hydrology, soil and water chemistry, and wildlife. Potential for contamination and ecological disruption is real — especially over long time periods and under changing climate / hydrologic conditions. Trace elements leaching, altered water regimes, soil moisture changes, and microclimate shifts can undermine wetland functions. • Biodiversity — especially wetland -specialist species — may be degraded, even if generalist species persist or increase. Changes in bird community composition and lower ecosystem "quality" have been observed. • Given gaps in the science, the precautionary principle should apply. Any PV proposal near wetlands should be evaluated with extra care: require full environmental review, baseline soil/ water/ biodiversity studies, long-term monitoring, and commitment to avoid or decommission if adverse effects appear. Therefore: For a project such as the proposed PV installation near Los Cerritos Wetlands, the evidence strongly supports either (a) relocating the project to a less -sensitive, non - wetland area, or (b) if no reasonable alternative exists, requiring rigorous mitigation measures, buffer zones, robust monitoring and adaptive management — and even then, weighing carefully whether the trade-offs are worth it, given the ecological value of the wetland.