Washington Lakes Research Articles

The influence of multidecadal climate variability and abrupt landscape change on terrestrial ecosystem composition and fire regime in the upper Columbia River basin - A high-resolution Holocene perspective

High-resolution paleoclimatic and paleoecologic datasets from a small lake in eastern Washington (USA) help elucidate Holocene environmental dynamics in the interior Pacific Northwest. Round Lake lies near the ecotone between sagebrush steppe and dry pine forest, making it highly sensitive to changes in precipitation-evaporation (P-E) balance. We present isotopic, sedimentological, and paleoecological data from a single sedimentary sequence analyzed at sufficient resolution to detect sub-decadal climatic variability. During the early Holocene (11,000–8500 cal yr BP), when summer insolation was higher than present, Round Lake experienced persistent aridity that led to reduced forest cover and small, probably frequent surface fires. Sub-centennial hydroclimate fluctuations during this period were muted, as indicated by low multi-decadal variability in δ18Ocarbonate records from the region. Oxygen isotopes indicate increased cool-season moisture during the middle Holocene (8500-5300 BP), but stratigraphic evidence suggests intermediate and variable lake levels. The deposition of the Mazama tephra (ca. 7600 cal yr BP) immediately preceded to a protracted expansion of steppe at the expense of forest. Increased hydroclimate variability and fire activity following ash deposition likely restricted conifer taxa even when elevated cool-season moisture would have facilitated their growth. The late Holocene was marked by persistently high lake levels, as indicated by the lithostratigraphic and pollen records. Comparatively large multidecadal variations in precipitation, which peaked during the last millennium, were also prominent features of late-Holocene hydroclimate, and may have been related to the strengthening of the El Niño Southern Oscillation and Pacific Decadal Oscillation. Pinus and Pseudotsuga show a 60–100 year lag in their response to hydroclimatic variations inferred from the oxygen isotope records. These results highlight how millennial-to-decadal scale hydroclimate conditions, along with abrupt landscape change, influence ecology in a water-stressed region of western North America.

A Link Between Hydroclimate Variability and Biomass Burning During the Last Millennium in the Interior Pacific Northwest

AbstractWe present oxygen isotope and charcoal accumulation records from two lakes in eastern Washington that have sufficient temporal resolution to quantitatively compare with tree‐ring records and meteorological data. Hydroclimate reconstructions from tree‐rings and lake sediments show close correspondence after accounting for seasonal‐ to centennial‐ scale temporal sensitivities. Carbonate δ18O measurements from Castor and Round lakes reveal that the Medieval Climate Anomaly (MCA) experienced wetter November‐March conditions than the Little Ice Age (LIA). Charcoal records from Castor, Round, and nearby lakes show elevated fire activity during the LIA compared to the MCA. Increased multidecadal hydroclimate variability after 1250 CE is evident in proxy records throughout western North America. In the Upper Columbia River Basin, multidecadal wet periods during the LIA may have enhanced fuel loads that burned in subsequent dry periods. A notable decline in biomass burning occurred with Euro‐American settlement in the late nineteenth century.

Annual and Interannual Variability in the Diffuse Attenuation Coefficient and Turbidity in Urbanized Washington Lake from 2013 to 2022 Assessed Using Landsat-8/9

Water clarity, defined in this study using measurements of the downwelling diffuse light attenuation coefficient (Kd) and turbidity, is an important indicator of lake trophic status and ecosystem health. We used in-situ measurements to evaluate existing semi-analytical models for Kd and turbidity, developed a regional turbidity model based on spectral shape, and evaluated the spatial and temporal trends in Lake Washington from 2013 to 2022 using Landsat-8/9 Operational Land Imager (OLI). We found no significant trends from 2013 to 2022 in Kd or turbidity when both the annual and full datasets were considered. In addition to the spring peak lasting from April through June, autumn Kd peaks were present at all sites, a pattern consistent with seasonal chlorophyll a and zooplankton concentrations. There existed no autumn peak in the monthly turbidity dataset, and the spring peak occurred two months before the Kd peak, nearly mirroring seasonal variability in the Cedar River discharge rates over the same period. The Kd and turbidity algorithms were thus each more sensitive to different sources of water clarity variability in Lake Washington.

Zooplankton recovery from a whole‐lake disturbance: Examining roles of abiotic factors, biotic interactions, and traits

AbstractCommunity assembly following disturbance is a key process in determining the composition and function of the future community. However, replicated studies of community assembly at whole‐ecosystem scales are rare. Here, we describe a series of whole‐lake experiments, in which the recovery of zooplankton communities was tracked following an ecosystem‐scale disturbance, that is, application of the piscicide, rotenone. Using a before‐after‐control‐impact design, 14 lakes in eastern Washington were studied: Seven lakes were treated with rotenone, while seven lakes acted as reference systems. Each lake was monitored up to 6 months before and 1–2 years after the rotenone treatments. Zooplankton samples and environmental measurements were collected approximately monthly from each lake. Community responses following disturbance were assessed using metrics of abundance, diversity, and community composition, as well as taxonomic group abundance. Zooplankton recovery was also assessed using species traits related to habitat, feeding mode, trophic level, body size, and life history. In addition to patterns of recovery, potential mechanisms were explored relating to abiotic conditions, biotic interactions, and traits. There were steep declines in the abundance (average across years: 99%) and diversity (average across years: 75%) of the zooplankton community following rotenone treatment. Although abundance had recovered by the second year of the study, community diversity had not fully recovered after 2 years. Communities from rotenone lakes appeared to be compositionally recovered within about 8 months following disturbance. Cyclopoid copepods were typically the first group to recover and remained dominant for a few months, whereas cladocerans recovered more slowly, typically within ~6–7 months following rotenone. Calanoid copepods were not fully recovered 2 years after rotenone treatment. Traits related to body size and feeding mode were associated with the zooplankton communities following rotenone treatment. We failed to observe significant spatial synchrony in recovery patterns of zooplankton across lakes, though we did observe significant synchrony of zooplankton taxonomic groups within lakes. These findings suggest that traits related to ecological function, and to a lesser extent, biotic, and abiotic factors, as well as characteristics of the disturbance itself, may be important in helping to understand recovery processes.

Effect of Moss Killer on Dissolved Oxygen and Turbidity of Western Washington Lakes

Several studies have been conducted on the effects of various pollutants on freshwater water systems in Washington state; however, research into the effects of increased concentrations of zinc, particularly via moss control products (representing a significant portion of the accumulative zinc pollution in Washington waterways) is scarce. The goal of this study is to shed light on the effect of moss control on the health of native aquatic microbial communities in Western Washington, measured via rate of change of dissolved oxygen and turbidity levels. Samples from Green Lake, Martha Lake, and Lake Washington were collected and introduced to varying concentrations of moss control, and the dissolved oxygen and turbidity levels of these samples were monitored over five days. It was discovered that there is a statistically significant negative correlation between concentration of moss control and both dissolved oxygen and turbidity. More research is needed to verify and further investigate these relationships.

Monitoring Variations in Lake Water Storage with Satellite Imagery and Citizen Science

Despite lakes being a key part of the global water cycle and a crucial water resource, there is limited understanding of whether regional or lake-specific factors control water storage variations in small lakes. Here, we study groups of small, unregulated lakes in North Carolina, Washington, Illinois, and Wisconsin, USA using lake level measurements gathered by citizen scientists and lake surface area measurements from optical satellite imagery. We show the lake level measurements to be highly accurate when compared to automated gauges (mean absolute error = 1.6 cm). We compare variations in lake water storage between pairs of lakes within these four states. On average, water storage variations in lake pairs across all study regions are moderately positively correlated (ρ = 0.49) with substantial spread in the degree of correlation. The distance between lake pairs and the extent to which their changes in volume are correlated show a weak but statistically significant negative relationship. Our results indicate that, on regional scales, distance is not a primary factor governing lake water storage patterns, which suggests that other, perhaps lakes-specific, factors must also play important roles.

Establish a Mathematical Model for Key Nutrients in Catfish Ponds

Catfish (Pangasius) is a famous and popular food in many countries around the world, and it has contributed greatly to the economy through exports. However, Pangasius farming without planning leads the fish to be more susceptible to disease and causing high pollution to the environment. The objective of this study is to use the mathematic model to identify the development processes of key nutrients in the catfish ponds. The model was used data from Washington lake and calibration and validation by measured data at the Vietnamese pond. The results showed that the actual PO₄^3- was in the range of 0.043 - 3.07 mg/l, PO₄^3- modeling in range of 0.043 to 1.956 mg/L; TP actual: 0.098 – 3.924 mg/L, TP modeling: 0.098 – 2.658 mg/L with an average error of the PO₄^3- and TP at the modeling graphs were 40% and 30.83%. The actual NO₃^- concentration: 0.018 - 0.8, modeling NO₃^-: 0.018 - 0.832 mg/L; actual NH₄⁺: 0.146 – 2.83 mg/L, NH₄⁺ modeling: 0.146 – 3.432 mg/L; actual TN: 0.442 - 5.55 mg/L, TN modeling: 0.442 - 5.852 mg/L, the average error of NO₃^-, NH₄⁺ and TN at the modeling graphs were 40.31%, 27.47% and 17.74%. The MSE and RMSE of of PO₄^3- in actual are 0.159 and 0.399 and in model are 0.000 and 0.016; TP in actual are 0.138 and 0.371 and in model are 0.000 and 0.003; NO₃^- in actual are 0.043 and 0.206 and in model are 0.000 and 0.000; NH₄⁺ in actual are 1.343 and 1.159 and in model are 0.005 and 0.072; TN in actual are 0.195 and 0.441, in model are 0.001 and 0.031, respectively. The result of modeled data was still in the range of environmental indicators was mentioned in much other research. It helps to control the development of environmental factors in the pond to optimize the fish production as well as reduce the impact to the received areas. The model need to be continuing research to identify the impact of external factors (weather, light, etc.,) and also reduce the errors for better management.

Catchment characteristics, water quality, and cyanobacterial blooms in Washington and Oregon Lakes

Rose VJ, Forney WM, Norton RA, Harrison JA. 2018. Catchment characteristics, water quality, and cyanobacterial blooms in Washington and Oregon Lakes. Lake Reserve Manage. 35:51–63A cyanobacterial bloom (CB) model specifically developed as a screening tool for at-risk and affected lakes would benefit natural resource managers and scientists seeking cost-effective monitoring and mitigation measures to prevent blooms. We tested whether water quality, land use/land cover (LULC), and lake morphometry data could explain CB occurrence in a dataset containing 60 lakes and reservoirs in the Pacific Northwest United States using univariate and multiple logistic regressions. Of the explanatory variables evaluated by univariate regression, chlorophyll a concentration was most strongly associated with CB occurrence (pseudo-r2 = 0.39). Other factors significantly related to CB occurrence included modeled dissolved inorganic phosphorus (DIP) yield, total phosphorus concentration (TP), “mixed forest,” “developed – open space,” and “developed – low intensity” (positive correlations), and water clarity, “evergreen forest,” and “barren land” (negative correlations). The best multiple regression model evaluated included the following independent variables: TP, “drainage area,” and “developed – open space” (AIC = 47.67, modified R2 = 0.53). We selected the best performing univariate model to test for lakes at risk of developing CBs to highlight how simple models based on water quality and LULC factors may be valuable tools for conducting preliminary screenings as part of a monitoring program. Consistent with other studies, our findings suggest an important role for phosphorus in controlling CBs in the Pacific Northwest. Our study indicates that, in addition to more traditionally used water quality data, LULC variables and modeled DIP yield are strongly associated with CBs and may be valuable in the development of predictive models.

Beyond Eutrophication: Vancouver Lake, WA, USA as a Model System for Assessing Multiple, Interacting Biotic and Abiotic Drivers of Harmful Cyanobacterial Blooms

Eutrophication of lakes and reservoirs has contributed to an increase in the magnitude and frequency of harmful cyanobacterial blooms; however, the interactive effects of nutrient availability (eutrophication) and other abiotic and biotic drivers have rarely been comprehensively studied in the field. We undertook an eight-year (2005–2013) research program that assessed the interaction of multiple factors driving cyanobacterial blooms in Vancouver Lake, a large, shallow eutrophic lake in Washington, USA. Our program consisted of nearly continuous monthly or weekly monitoring of water quality and plankton community composition over eight years, as well as multiple zooplankton grazing experiments over three years. We found a relatively consistent seasonal succession of phytoplankton and zooplankton assemblages, and a pattern of interacting factors influencing cyanobacterial bloom dynamics. Typically, a combined effect of decreased dissolved inorganic nitrogen (N), a sudden increase of dissolved inorganic phosphorus (P), and a cascading effect of zooplankton grazing created a ‘perfect storm’ of conditions that promoted the rapid proliferation of cyanobacteria over the two to three weeks before a bloom. At the blooms’ peaks, cyanobacterial carbon biomass reached as high as 20 µg L−1, with total [chl a] often exceeding 750 µg L−1. In the weeks following the blooms’ peaks, [PO4-P] and [NH4-N] dropped and copepod feeding rates fell to near zero, whereas microzooplankton grazing rates reached their maxima. Microzooplankton grazing impact, combined with low nutrient availability, then drove down cyanobacteria abundance. Vancouver Lake serves as a model for understanding multiple, interacting drivers of cyanobacterial bloom dynamics in shallow, temperate lakes, and is therefore an important system in which to investigate new questions related to the science and management of harmful algal blooms.

Last Millennium Meridional Shifts in Hydroclimate in the Central Tropical Pacific

AbstractReconstructing past changes in the spatial structure of tropical Pacific hydroclimate requires archives of past moisture balance across spatial gradients of precipitation. To date, only one, 600‐year, terrestrial record of hydroclimate is available for the central tropical Pacific (CTP) from Washington Lake, Washington Island, limiting the ability to test the hypotheses regarding the location of the CTP Intertropical Convergence Zone (ITCZ) in the last millennium. A new lake sediment record from Lake 30, Kiritimati, Republic of Kiribati, 3° south of Washington Island, provides additional constraints on past CTP ITCZ position. Lake 30 geochemical and sedimentological data indicate an episode of increased microbial mat development and gypsum precipitation from 900 to 1200 CE, coincident with the Medieval Climate Anomaly (MCA). We infer drier conditions during the MCA at Kiritimati as the Washington Lake proxy record indicates wetter conditions, suggesting that the CTP ITCZ was displaced northward during the MCA relative to its position today. At the transition between the MCA and the Little Ice Age (LIA), Lake 30 sediment becomes predominantly carbonate, suggesting a transition to wetter conditions and a southward shift of the ITCZ relative to its MCA position. However, a tropical Pacific synthesis of hydroclimate‐sensitive proxy records does not point to a consistent spatial or temporal pattern of variability in the MCA and LIA, suggesting multiple influences on centennial‐scale tropical Pacific hydroclimate during the last millennium.

Genome Sequence of Prosthecochloris sp. Strain HL-130-GSB from the Phylum Chlorobi.

ABSTRACTThe genome of the green sulfur bacterium Prosthecochloris sp. strain HL-130-GSB, isolated from a cyanobacterial mat obtained from Hot Lake, a saline meromictic lake in Washington, USA, comprises 2,437,774 bp in a single contig. The genome is predicted to encode 2,565 proteins and contain 47 tRNA genes and 2 rRNA operons.

Bigger is Better: Optimizing Trout Stocking in Western Washington Lakes

AbstractThe effect of the length of Rainbow Trout Oncorhynchus mykiss on catch rate, catch size, and cost of stocking was evaluated in two western Washington lakes. Rainbow Trout of two general length‐classes (200–300 [“catchables”] and 300–400 mm [“jumbos”]) were differentially marked and stocked 1 d prior to a fishery utilizing typical sportfishing techniques. In both study lakes, larger trout represented a larger proportion of the total catch than would have been expected if proportional to lengths at stocking. Fish in the largest individual length‐class (360–380 mm) were, on average, 12.5 times more likely to be caught by sport anglers than those in the smallest individual length‐class (200–220 mm). Larger Rainbow Trout are more expensive to produce for stocking agencies. However, fish stocked in the 280–300‐mm class were twice as likely to return to the creel as expected and therefore are the best value in terms of number of fish caught per dollar invested. The results of this study suggest that a stocking strategy aimed at stocking fish 280 mm or larger would result in lower cost overall and increased satisfaction from anglers. Additionally, stocking Rainbow Trout less than 280 mm appears to have minimal recreational value in western Washington lakes.Received July 14, 2016; accepted January 7, 2017 Published online April 4, 2017

Bacterial growth tolerance to concentrations of chlorate and perchlorate salts relevant to Mars

AbstractThe Phoenix lander at Mars polar cap found appreciable levels of (per)chlorate salts, a mixture of perchlorate and chlorate salts of Ca, Fe, Mg and Na at levels of ~0.6% in regolith. These salts are highly hygroscopic and can form saturated brines through deliquescence, likely producing aqueous solutions with very low freezing points on Mars. To support planetary protection efforts, we have measured bacterial growth tolerance to (per)chlorate salts. Existing bacterial isolates from the Great Salt Plains of Oklahoma (NaCl-rich) and Hot Lake in Washington (MgSO4-rich) were tested in high concentrations of Mg, K and Na salts of chlorate and perchlorate. Strong growth was observed with nearly all of these salinotolerant isolates at 1% (~0.1 M) (per)chlorate salts, similar to concentrations observed in bulk soils on Mars. Growth in perchlorate salts was observed at concentrations of at least 10% (~1.0 M). Greater tolerance was observed for chlorate salts, where growth was observed to 2.75 M (>25%). Tolerance to K salts was greatest, followed by Mg salts and then Na salts. Tolerances varied among isolates, even among those within the same phylogenetic clade. Tolerant bacteria included genera that also are found in spacecraft assembly facilities. Substantial microbial tolerance to (per)chlorate salts is a concern for planetary protection since tolerant microbes contaminating spacecraft would have a greater chance for survival and proliferation, despite the harsh chemical conditions found near the surface of Mars.

Seeking Northlake: Place, technology, and public as enabling constraints for urban transdisciplinary research

This article reviews the urban transdisciplinary research of the Northlake Collective, a multidisciplinary group of graduate students in the University of Washington's Lake Union Laboratory. Through a series of place-based investigations, we explored a small slice of Seattle ultimately seeking to engage the public through an online digital humanities portal. The broader goal of our work and this paper is to address how we, as a team of emerging scholars, understand and investigate ‘cities’ in the current century as both networked at the global scale and dynamic places for everyday interactions and processes. The paradoxes and complexity inherent to understanding the ‘city’ and how to address these concerns led us to develop a framework that might enrich grounded urban theory through the ‘enabling constraints’ of place, technology and public. The productive character of these three concepts, combined with the practical constraints and interrelationships they bring to bear, allowed us to deepen our work and produced the context for our research of Northlake. We propose this tripartite framework for exploring the contemporary city via the structure afforded by transdisciplinary, born-digital collaborations.

Relationships between sucretolerance and salinotolerance in bacteria from hypersaline environments and their implications for the exploration of Mars and the icy worlds

AbstractThe most extremely osmotolerant microbial isolates are fungi from high-sugar environments that tolerate the lowest water activity (0.61) for growth yet reported. Studies of osmotolerant bacteria have focused on halotolerance rather than sucretolerance (ability to grow in high sugar concentrations). A collection of salinotolerant (≥10% NaCl or ≥50% MgSO4) bacterial isolates from the Great Salt Plains of Oklahoma and Hot Lake in Washington were screened for sucretolerance in medium supplemented with ≥50% fructose, glucose or sucrose. Tolerances significantly differed between solutes, even though water activities for saline media (0.92 and 0.85 for 10 and 20% NaCl Salt Plains media, respectively) were comparable or lower than water activities for high-sugar media (0.93 and 0.90 for 50 and 70% sucrose artificial nectar media, respectively). These specific solute effects were differentially expressed among individual isolates. Extrapolating the results of earlier food science studies with yeasts at high sugar concentrations to bacteria in salty environments with low water activity should be done with caution. Furthermore, the discussion of habitable Special Regions on Mars and the icy worlds should reflect an understanding of specific solute effects.

Cyanotoxin bioaccumulation in freshwater fish, Washington State, USA.

Until recently, exposure pathways of concern for cyanotoxins have focused on recreational exposure, drinking water, and dermal contact. Exposure to cyanotoxins through fish consumption is a relatively new area of investigation. To address this concern, microcystins and other cyanotoxins were analyzed in fish collected from nine Washington lakes with recurrent toxic blooms using two types of enzyme-linked immunosorbent assays (ELISAs) and liquid chromatography/mass spectrometry/mass spectrometry (LC-MS/MS). Microcystins or microcystin-like compounds were elevated in fish liver relative to muscle and other tissues (liver>gut>muscle). Microcystin concentrations in fish fillet samples using anti-Adda ELISA (range 6.3-11 μg/kg wet weight) were consistently higher in all fish species than concentrations using anti-microcystin (MC)-leucine-arginine (LR) ELISA (range 0.25-2.4 μg/kg wet weight). MC-leucine-alanine (LA) was the only variant detected in fish (2.5-12 μg/kg in four livers) among the nine variants analyzed by LC-MS/MS. Fish fillets showed no accumulation of the MCs targeted by LC-MS/MS. Other cyanotoxins analyzed (anatoxin-a, saxitoxin, domoic acid, and okadaic acid) were not detected in fish. Based on this and evidence from other studies, we believe that people can safely consume two 8-oz fish fillet meals per week from lakes with blooms producing MCs (clean the fish and discard viscera).

A new species of Diaphanosoma Fischer, 1850 (Crustacea: Branchiopoda: Sididae) inhabits lakes of the western United States

<p><em>Diaphanosoma edmondsoni </em>sp. nov. is described from material from several lakes in Washington, California, and Montana. It differs from all other known species of the genus in having a specific combination of traits: a head with conspicuously protruding dorsal part, comparatively small eye shifted ventrally, specific armament of postero-ventral valve margin, lack of thorn(s) near posterior valve margin, comparatively long distal basal spine of postabdominal claws of slightly variable shape, and occasional presence of additional large spines on the claws. This is the first endemic species of the genus (and also of the family Sididae and order Ctenopoda) recorded in the western part of North America, which along with some other cladocerans form a group of taxa highlighting this region as one of the regional centers of endemic aquatic fauna. <strong></strong></p>

Lake and reservoir volume: Hydroacoustic survey resolution and accuracy

Volume measurements are essential for a wide variety of lake and reservoir applications, with recent technological and computational advances greatly improving volume estimate accuracy. Triangulated irregular network bathymetric models, created with spatially referenced depth data, are now commonly available for computer processing. Large datasets can easily be handled in geographic information system software, but field data acquisition is the principal time investment; therefore, determining minimum data density requirements associated with accurate volume estimates has great practical and economic relevance. We used spatially referenced hydroacoustic depth data acquired along parallel transects to assess survey resolution required to obtain accurate volume measures on 5 northeastern Washington lakes and reservoirs. Volume estimates decreased in each study waterbody as sampling resolution decreased, exhibited by significant (P < 0.0001) monotonic decreasing functions. Our study showed that hydroacoustic surveys with 50 m transect spacing were 99.0–99.6% (95% confidence interval, 98.3–100.5%) accurate compared to modeled volume. Across all study sites, volume estimates based on 300 m spaced transect surveys averaged 4.2 and 9.6% lower, with and without near-shore transects, respectively, when compared to 50 m spaced transect surveys. The addition of a near-shore transect increased the accuracy of volume estimates at large transect spacings, especially when large near-shore changes in depth were missed. As expected, higher sampling resolution increased volume estimate accuracy; however, our results suggest that survey effort should focus on topographically complex areas, such as near-shore areas, when time and/or economic constraints limit the acquisition of data.

The use of parasites as indicators of ecosystem health as compared to insects in freshwater lakes of the Inland Northwest

Trematode parasites have complex life cycles, requiring multiple hosts. If these parasites are present in an ecosystem, then one can infer that their respective hosts must also be present. Thus, these parasites may serve as reliable indicators of species diversity in an ecosystem. To test this, we sampled larval trematodes and aquatic insects from three freshwater lakes in Idaho that varied in heavy metal pollution and three lakes in Washington that varied in agricultural use. We hypothesized that if parasites do serve as reliable indicators of ecosystem health, then parasite diversity should be higher at the least disturbed sites and should positively correlate with insect diversity. We found that the Shannon diversity index for parasites was highest at the WA reference lake (1.36) compared to the two WA lakes (0.54 and 0) exposed to cattle grazing. The ID lake with the highest levels of heavy metals experienced the highest insect diversity, but a low trematode diversity. We conclude that parasite diversity indices work as well as insect diversity indices as indicators of ecosystem health, especially in instances of heavy metal pollution.

Climatic analysis to determine where to collect and release Puccinia jaceae var. solstitialis for biological control of yellow starthistle

Puccinia jaceae var. solstitialis is an autoecious rust fungus that is native to areas of Afro-Eurasia with a Mediterranean climate. An isolate collected near Sivas, Turkey was released for classical biological control of yellow starthistle (YST), which is an invasive alien weed in California, USA. The fungus has been released throughout California, but long-term establishment rates are generally low, apparently because this ecotype is not well adapted to the climate where the weed is most invasive. Using a site with excellent establishment as a target, the Match Climates function in CLIMEX climate modeling software identified similar sites in and around the San Francisco Bay Area, east to the Central Valley and Sierra foothills, and along the coast of Southern California. Similar sites in other states include Walla Walla, Washington, Pendelton, Oregon and Salt Lake City, Utah. A Compare Locations model based primarily on experimentally measured temperature and humidity requirements of the rust produced similar results. Using Sacramento, California, which is in the center of YST distribution, as a target, the Match Climates function predicted that the best locations to search for rust accessions to use in California are near Tunis, Tunisia, Foggia, Italy, Khalkis, Greece, Kayseri, Turkey, and possibly Constantine, Algeria. This generally agrees with the prediction of a Compare Locations model based on the geographic distribution of YST in California. Climatic factors that limit the long-term establishment of the fungus are likely to be summer heat and/or dry stress and short dew periods.