Review of the manuscript: "Warming of the Willamette River, 1850–present: the effects of climate change and direct human interventions" by Talke et al. In its current state, it is far from a scientific research paper, instead a technical report.  Most of the content in the discussion of results and conclusions are merely descriptions of their results and a list of general knowledge without any significant novel contribution. If the authors manage to rewrite the manuscript some notes about minor details are below:

1. What are exactly system changes mentioned in the short summary? Authors should use some related technical terms.
2. What is the novelty of this paper? Can the author mention some scientific applications including the novel idea?
3. Line 87-88: The statement is not clear. How warming climate and hotter extremes are linked to land-use changes?
4. Line 97-98: What is the characterization of natural variability? How it is linked to climate change?
5. Line 100-101: What are the natural and background condition? Please mention.
6. Line 106: What are chronic and acute anthropogenic factors? Describe with some examples.
7. Line 114-120: Remove these results from the introduction section.
8. Line 122: Study area will be more appropriate than the setting.
9. Section 2 and its subsequent sections are quite lengthy and not clear. This should be short, precise and reader-friendly. Some results are discussed in this section which should be moved to the result and discussion section.
10. Importance is given to the derivation of T_w in this paper while the paper tile is suggesting the impact of climate change and direct human intervention. Authors can change accordingly.
11. Can uncertainty be assessed using RMSE? Any reference to this statement? Or authors can consider separate uncertainty analysis.
12. Section 3.3.1: How the authors have evaluated the % of T_w change (mentioned in short summary that 30% from system change and 70% from climate change)?
13. Have the authors used any particular separation/attribution analysis? If not then how % of the contribution is shown?
14. Line 746: How the authors used the sensitivity studies? Describe it in methodology.
15. Line 782: How are the system changes estimated by changing regression coefficients? Please explain.
16. In Section 2, several anthropogenic factors are discussed. The authors should consider these factors in attribution analysis.
17. What is the significance of precipitation in this work? As precipitation is an important climatic variable, it can't be ignored in this analysis. The authors can refer following articles. (* Swain, S. S., Mishra, A., Chatterjee, C., & Sahoo, B. (2021). Climate-changed versus land-use altered streamflow: A relative contribution assessment using three complementary approaches at a decadal time-spell. Journal of Hydrology, 596, 126064. * Liang, S., Wang, W., Zhang, D., Li, Y., & Wang, G. (2020). Quantifying the impacts of climate change and human activities on runoff variation: case study of the upstream of Minjiang River, China. Journal of Hydrologic Engineering, 25(9), 05020025.)
18. Figures should not be cited in the conclusion. Please rewrite this section.
19. Line 902: The citation of Jay and Naik, 2011 is wrong. Citations should be in a uniform manner followed by HESS guidelines.
20. Proper proof-reading is needed, but more importantly, better use of technical language and precise description is lacking throughout the manuscript.

General Comments:

The manuscript gives a thorough investigation of changes in stream temperature in the Willamette river from the 1850s to the present. The authors compile air temperature, discharge, and stream temperature data from a variety of sources throughout the region, and use these data to construct statistical models that give insight into the magnitude of change in stream temperature throughout three different historical periods. The authors then investigate the seasonal and interannual changes in observed stream temperature records and validate their models by comparing model accuracy (including a comparison to other stream temperature predictions in the same region.) The models are then used to quantify the importance of climatic and system changes (notably reservoirs, loss of shading, and landscape alterations) over time, with good quantification of how the two compare in magnitude and seasonality using sensitivity experiments.   

The results of this paper give a clear insight into how and why stream temperatures are changing in the Willamette river, investigate the causes of these changes, and draw connections to the ecological impacts of rising stream temperatures. While the paper is well framed, the extensive methods section makes it difficult for the reader to keep track of the different data sources and to get a clear and concise understanding of how the models presented in the results were constructed. Thus, the manuscript could benefit from making the methods section more concise, contextualizing the model with other models that have been used for stream temperature modeling, with additional information made available in supplemental materials. Overall, the model results and analysis substantiate the manuscript’s conclusions about changing temperatures in the Willamette river over time. Finally, the digitization of historical observations since the mid-19th century adds value as data are sparsely available for these time periods, but are not yet archived for public use, detracting from the overall impact of the paper. 

Specific Comments:

1. The authors provide extensive detail about the specific climate and long-term changes in the region. Because the detail of different regions is so extensive, it is difficult for a reader who is not familiar with the study area to distill the historical changes of the region to understand how system impacts have changed over time. A more concise description would help the reader to focus on key points which are integrated into the model methodology. Additionally, contextualizing the changes in the Willamette river with other river basins in the continental U.S. (e.g. other basins with similar snowmelt influence) in the introduction (rather than just referring to similar studies in the discussion) could help a broader audience understand the study area before getting into methods and results. 

1. Section 2.3: While the discussion of the advection-diffusion equation provides important information about how physical understanding can help inform accurate statistical model architecture, the in-depth analysis detracts from the reader’s ability to understand the equations used for the final statistical models that are run and used for reporting results. Shortening sections 2.3 and 2.4 and/or highlighting what equations relate to the final chosen models will greatly help the readability of the methods

1. Lines 509-510: The authors refer to the “total of 8 statistical models” that are developed (listed in Table 2). When the reader refers to Table 2, however, there are 7 different stations named, implying that there are not 8 but 7 different models. Furthermore, it is difficult to decipher the governing equations for these models, and if the only major difference is the data sources and time periods used for each. Clarification would help greatly in this section of the manuscript.

1. While there is extensive discussion of how the chosen statistical model was derived, there is no noted comparison to other statistical stream temperature methods making it difficult to put this model in the context of previous statistical models which are also derived from physics-based equations. Adding information on how this model compares to other statistical models (such as air2stream, ARIMA models etc.) would help give a better understanding and context to readers familiar with stream temperature modeling, and help make these methods more applicable to other systems. 

1. The authors mention 8 different models (line 509), however, the text does not clearly explain what differentiates these 8 different models. iTable 2 includes 7 different models. Including a table of the different models, and some measure of comparative accuracy for the summer vs. winter sub-models would be helpful.

1. Line 969: The manuscript states that “The water temperature data used in the research is available upon request, and will be uploaded to a data repository upon acceptance of the manuscript.” With other meteorological and flow data available from other sources. Because the procurement of data used in this study is a large value add, publishing all data in a corresponding data package together (if possible) will greatly improve the open use of data from this study. 

Tecnical Corrections:

Line 245: Missing space– should read “1881– 2021 record”

Table 2: 10th column (RMSE Winter Calibration) Does not properly align/format with 11th column should be fixed.

Figure 3: the x-axis of the bottom right-hand figure (d) is cut off and should be fixed.