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Peer-Review Record

High-Resolution Assessment of Riparian Impervious Cover Across Watersheds to Inform Land Use Policy and Management

Sustainability 2026, 18(10), 5141; https://doi.org/10.3390/su18105141

by Daniel A. Auerbach¹

, Kenneth B. Pierce^1,*

, Ken Muir¹

, Keith Folkerts¹, Robin Hale¹, Kara A. Whittaker¹

, Simone Des Roches¹

, Danielle Lazarus² and John Withey²

Reviewer 1:

Jonathan J. Halama

Reviewer 2: Anonymous

Reviewer 3: Anonymous

Reviewer 4: Anonymous

Sustainability 2026, 18(10), 5141; https://doi.org/10.3390/su18105141

Submission received: 4 February 2026 / Revised: 20 April 2026 / Accepted: 13 May 2026 / Published: 20 May 2026

(This article belongs to the Special Issue Sustainable Geography and Urban Planning: Urban Ecology, Livability, Nature Connection, and Water-Sensitive Urban Design)

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Excellent research. The RMZ dataset will be extremely useful for many focusing on stream habitat health.

Besides some writing and figure suggestions below, consider including aspects of fish habitat cold water refugia becoming increasingly disparite. You discuss how your riparian analysis reveals urbanized areas versus upstream forested areas differ, but that in itself will not impact fish populations. Discussing how it will impact fish populations by further degrading remaining quality stream habitat is a direct link to your analysis. I do not think this requires any new or further analysis. This idea could be included in just the discussion.

Few manuscripts on this idea...
Mejia FH, Ouellet V, Briggs MA, Carlson SM, Casas-Mulet R, Chapman M, Collins MJ, Dugdale SJ, Ebersole JL, Frechette DM, Fullerton AH, Gillis CA, Johnson ZC, Kelleher C, Kurylyk BL, Lave R, Letcher BH, Myrvold KM, Nadeau TL, Neville H, Piégay H, Smith KA, Tonolla D, Torgersen CE. Closing the gap between science and management of cold-water refuges in rivers and streams. Glob Chang Biol. 2023 Oct;29(19):5482-5508. doi: 10.1111/gcb.16844. Epub 2023 Jul 19. PMID: 37466251; PMCID: PMC10615108.

D.A. Roon, J.B. Dunham, C.E. Torgersen. A riverscape approach reveals downstream propagation of stream thermal responses to riparian thinning at multiple scales, Ecosphere, 12 (2021), Article e03775, 10.1002/ecs2.3775

Fullerton, A. H., C. E. Torgersen, J. J. Lawler, R. N. Faux, E. A. Steel, T. J. Beechie, J. L. Ebersole, and S. G. Leibowitz. 2015. Rethinking the longitudinal stream temperature paradigm: region-wide comparison of thermal infrared imagery reveals unexpected complexity of river temperatures. Hydrological Processes. DOI: 10.1002/hyp.10506

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Few suggestions to improve writing:
Line 21: suggest "high resolution (1m)"
Lines 66-72: this sentence(s) [due to changes already tracked, bit unclear if already one or two sentences in my copy] has "and" numerous times. Suggest rewording or making two/three sentences to convey message.

Was about to comment a table would really help to summarize all the differing resolutions/scales. Appreciate Table 1.
- Author decision on this. I suggest including the m^2 or km^2 where there are hectares. People gravitate toward one or other. But here much of the data are in meter^2 resolution.

Figure 1 the purple is very difficult to see when the dark green floodplain is in background. Suggest a different color. Probably black line for the StreamCat rp100 100m buffer

Personal style: I would have figure referencing like "Figure 3 a" be "Figure 3a". when "a" is spaced out floating it makes one question if an error.

Paragraph lines 333 thru 341 are very important and very interesting! I was able to follow the analysis, but had to reread a few times. Partly what threw me off was "compare Figure 3 e and f to Figure 2 e and f, Figure 4, a and b". I suggest expanding the text here, probably just another sentence, to guide the reader a little more. maybe focus on "compare Figure 3 e and f to Figure 2 e and f" then further your point with follow-up sentence regarding "Figure 4, a and b".

Table 2, there seems to be no explanation why Wahkiakum county has only Non-UGA; dashed out UGA?

Line 410: suggest something like "In contrast, within urbanized areas the hydrographic representation is less varied for the lower mainstem reaches where human alteration of land cover tends to be more prevalent."

Line 452: "these results do not"
Line 536: suggest "ongoing change is critical toward protecting"

Author Response

Excellent research. The RMZ dataset will be extremely useful for many focusing on stream habitat health.

Thank you; we hope these data will see continued development to further enhance their utility for planners and conservation practitioners.

We appreciate this good suggestion, and the ideas in the proposed papers factor into other ongoing research projects centered more clearly on population dynamics relative to riverscape alteration. We did not include this material, however, as it seemed best suited to a more detailed treatment of spatial patterns within networks.

Few manuscripts on this idea...

Mejia FH, Ouellet V, Briggs MA, Carlson SM, Casas-Mulet R, Chapman M, Collins MJ, Dugdale SJ, Ebersole JL, Frechette DM, Fullerton AH, Gillis CA, Johnson ZC, Kelleher C, Kurylyk BL, Lave R, Letcher BH, Myrvold KM, Nadeau TL, Neville H, Piégay H, Smith KA, Tonolla D, Torgersen CE. Closing the gap between science and management of cold-water refuges in rivers and streams. Glob Chang Biol. 2023 Oct;29(19):5482-5508. doi: 10.1111/gcb.16844. Epub 2023 Jul 19. PMID: 37466251; PMCID: PMC10615108.

##########################################################
Few suggestions to improve writing:
Line 21: suggest "high resolution (1m)"

Changed

Lines 66-72: this sentence(s) [due to changes already tracked, bit unclear if already one or two sentences in my copy] has "and" numerous times. Suggest rewording or making two/three sentences to convey message.

Changed

Was about to comment a table would really help to summarize all the differing resolutions/scales. Appreciate Table 1.

- Author decision on this. I suggest including the m^2 or km^2 where there are hectares. People gravitate toward one or other. But here much of the data are in meter^2 resolution.

Square kilometers added

Figure 1 the purple is very difficult to see when the dark green floodplain is in background. Suggest a different color. Probably black line for the StreamCat rp100 100m buffer

Figure substantially revised for clarity

Personal style: I would have figure referencing like "Figure 3 a" be "Figure 3a". when "a" is spaced out floating it makes one question if an error.

We agree and are unsure how this formatting was present in the version provided for review.

Table 2, there seems to be no explanation why Wahkiakum county has only Non-UGA; dashed out UGA?

We agree this was unclear and placed too great a demand on readers. This text and the referenced figures have been substantially revised to reduce comparison across panels of different figures. Wahkiakum does not have Urban Growth Areas.

Text removed

Line 452: "these results do not"
Sentence revised

Line 536: suggest "ongoing change is critical toward protecting"

Sentence revised

Reviewer 2 Report

Comments and Suggestions for Authors

This study takes riparian impervious cover in Washington State as the research object, conducts landscape-scale dynamic assessment combined with high-resolution remote sensing data, and compares the assessment effects of different resolution and buffer zone delineation methods. The research topic is closely aligned with the practical needs of urban aquatic ecological management and land use policy formulation, the research methods have certain innovativeness, and the research results provide data support for regional riparian ecological protection. However, there is still room for improvement in the details of research methods, the depth of result analysis, the solution to research limitations, and the excavation of practical application value. The specific revision suggestions are as follows:

Insufficient description of key details in the manual review link of the HRCD method in Section 2.2 of Materials and Methods. Only the review of candidate polygons by analysts is mentioned, without clarifying the professional background and qualification requirements of the reviewers, nor explaining the inspection method of review consistency and quality control standards. At the same time, the corresponding dimension of the proportion and sample size of "1-4% or roughly n=1,000−40,000" is not explained, making it impossible for readers to clarify the spatial or temporal basis for its value selection. Relevant information needs to be supplemented to improve the repeatability and scientificity of the research method.

The Results section only presents the quantitative characteristics, spatial distribution of riparian impervious cover increase in Washington State, and the associated data with salmon habitats and urban growth areas, without conducting correlation analysis combined with the current riparian regulatory policies and land use planning in different regions of the state. It fails to reflect the combination of research data and regional management practices, making it difficult for readers to understand the policy and management drivers behind the research results. This dimension of analysis needs to be supplemented to highlight the practical value of the research results.

In the Discussion section, the solutions to research limitations only propose technical directions without analyzing their feasibility in combination with the actual situation of Washington State. For example, when mentioning solutions such as "LiDAR derived watercourses" and "spatial interpolation of soilssite index values", the acquisition and coverage of LiDAR data in the state and the technical implementation conditions of soil site index interpolation are not considered, nor are the administrative, technical or cost problems that may be faced in the implementation of the solutions analyzed, resulting in the lack of operability of the solutions. The expression needs to be optimized in combination with regional reality to enhance the reference value.

The practical application value and policy implications of the research are not elaborated in detail. Although it is mentioned in the conclusion that the research can provide a reference for the formulation of riparian land use policies, specific regulatory optimization and development control suggestions are not put forward for key areas such as urban growth areas and core salmon habitats in combination with the research results, nor is it clear how the research results can guide specific work such as low-impact development practices and riparian ecological restoration. Targeted application directions and implementable policy suggestions need to be supplemented in combination with research data to strengthen the practical guiding significance of the research.

The comparative analysis of the two assessment methods, RDE-HRCD and StreamCat-NLCD, in the paper is not systematic and in-depth. Only the result differences, error sources and data resolution differences between the two are pointed out, without conducting a comprehensive comparison from the three core dimensions of data accuracy, analysis efficiency and application scenarios. It is impossible to provide a method selection basis for riparian assessment work with different research purposes and different regional scales. This dimension of comparative analysis needs to be supplemented to improve the methodological research content.

Author Response

The description of HRCD processing has been increased substantially in L199-242. If desired, the internal protocol manuals can also be cited.

Thank you for this helpful feedback. We appreciate the interest in a better description of the practical value of the research results and have added paragraphs to the Discussion that 1) address why a full quantitative correlation analysis was beyond the scope of this paper (L505-517) and that 2) indicate some of how the RDE-HRCD information has factored into active regulatory policy (L518-526).

Thank you for this suggestion. We are keenly aware of the administrative and budgetary constraints shaping ongoing development of this and related public technical resources, and we have added text to better indicate the feasibility of some of the proposed next steps (L432-436). In addition to the statewide LiDAR hydrography effort already well underway, the research to address data gaps in the SPTH200yr layers is an agency priority.

Thank you for this suggestion. We value the interest in practical applications and, as noted above, have added a brief description of how the research has begun to contribute to adoption of more protective riparian regulatory standards. If desired, we could supplement this with further examples of how RDE datasets enable planners to rapidly screen a watershed for locations suited to restoration or protection through acquisition (e.g., targeting reaches with low or high tree canopy cover relative to upstream or downstream locations).

Thank you for this feedback. We agree that the comparative presentation warranted refinement. Our original intent in including the Streamcat-NLCD information was to provide an “illustrative contrast” rather than a detailed comparative analysis and validation. The accuracy and efficiency of Streamcat and NLCD are addressed in the cited publications and associated supporting materials, but we have revised to better convey the role of these coarser national data as an aid to thinking about the strengths and limitations of the “best available” high resolution data (rather than as a corroboration or directly comparable resource). Lines 466-504 contain revised descriptions in addition to those in Table 3. A more comprehensive description of change analysis using categorical land cover products would involve addressing the complexity of many-to-many pixel transitions between time points and was beyond the scope of this manuscript. However, we have attempted to convey our experience regarding likely applications of lower and higher spatial resolution land cover data, in particular the influence of the necessary temporal depth of record (i.e., favoring coarser but more consistently available Landsat-derived datasets).

Reviewer 3 Report

Comments and Suggestions for Authors

refer to attached comments

Comments for author File: Comments.pdf

Author Response

This manuscript, “High resolution, landscape scale assessment of riparian impervious cover across watersheds to inform land use policy and management,” dives deep into how impervious surfaces have changed in riparian zones across Washington State. Using an innovative 1-meter High Resolution Change Detection (HRCD) dataset from 2011–2017, the study goes head-to-head with the much coarser 30-meter satellite imagery (StreamCat-NLCD). The differences are striking—high-res data spots small increases in impervious cover, often less than 900m², that slip past traditional sensors.

The statistical analysis jumps off the page. Figure 5 shows 80.5% of change events were smaller than a single 30-meter pixel. No wonder high-res monitoring is crucial—regulators need this detail to enforce compliance. Stratifying data by UGA and salmon presence adds essential socio-ecological context.

Conclusions are solid and backed by the evidence. The discovery that most changes happened outside local regulatory jurisdictions points to a glaring policy gap. Even if annual increases (like 158 ha/year for RDE-HRCD) sound modest, their focus on salmon-bearing reaches threatens “no net loss” goals. There’s urgency here—the stakes are clear.

Looking ahead, a few tweaks could make this work even stronger:

- The manuscript notes StreamCat-NLCD probably overestimates change in arid east Washington due to bare soils or rocks mislabelled as impervious. A detailed table or appendix comparing these “false positives” between datasets would bolster the case for high-res imagery.

Thank you for this feedback. This statement was based on our experience manually inspecting different datasets, and we agree that a more systematic treatment might have been a worthwhile addition. (We even contemplated conducting a standalone analysis not limited to riparian extents.) However, we have removed this text as part of a broader revision to better reflect the original intent of including the Streamcat-NLCD as an “illustrative contrast” rather than as a focus of detailed comparative analysis and validation.

- Regulatory framing needs more substance. How might these findings update Critical Area Ordinances (CAOs) in Washington? A focused discussion could bridge the science-policy divide.

Thank you for this encouragement. We appreciate the interest in a better description of the practical value of the research results. We have added text to the Discussion that briefly describes some of how the RDE-HRCD information has factored into active regulatory policy contexts, including contributing to the adoption of more protective riparian regulatory standards (L518-526). This statewide assessment has not been the focus of specific legal proceedings, but the research surrounding it has and continues to support agency technical positions.

- For readers, visuals matter. A side-by-side comparison—something like Figure 1—showing a small-scale change invisible in NLCD but clear in HRCD would hit home.

We agree, and we have revised Figure 1 with additional “higher zoom” panels to better illustrate the scale of typical HRCD polygons relative to assessment extents. We also considered including a depiction of NLCD alongside HRCD, but a pixel scale visualization of change analysis using categorical land cover products would also involve addressing the complexity of many-to-many class transitions between time points, which we wished to avoid in this manuscript (particularly given the revisions to de-emphasize direct comparisons).

- There’s a need for transparency around RMZ buffer estimates. The authors should spell out limitations when defaulting to 100ft buffers where site index data are absent. Explaining whether this overstates or understates riparian area would clear up statewide estimates.

We have added text indicating that this missing data typically yields an RMZ dimension smaller than would otherwise be assigned. As noted to another review, the research to address data gaps in the SPTH200yr layers is an agency priority.

Reviewer 4 Report

Comments and Suggestions for Authors

The manuscript assesses riparian impervious-cover change across Washington State using a 1 m high-resolution change-detection workflow for 2011 to 2017, compares those results with 30 m StreamCat/NLCD estimates built on a different hydrography and fixed buffer, and adds a 2021 1 m CCAP standing-cover assessment. The manuscript reports hundreds of hectares per year of additional riparian impervious cover, strong concentration within urban growth areas, and higher relative density in salmon-associated reaches. The topic is important and the datasets are potentially valuable. However, the current draft is not yet ready because the two main assessment approaches are not sufficiently harmonized, uncertainty is discussed only qualitatively, and the manuscript contains substantial unresolved language and editing problems. I encourage the authors to revise carefully and consider the comments before further consideration.

Major comments

Problem: The manuscript is not in publication-ready prose. Numerous sentences contain visible editing artifacts, duplicated phrases, broken word joins, and unresolved revision text in the abstract, introduction, discussion, and conclusions.
Why it matters: This is not a cosmetic issue. It impairs meaning, makes several claims ambiguous, and raises concern that scientific statements may also not have been fully stabilized.
Recommendation: The authors should fully clean the manuscript before further review, then re-check every section for internal consistency after copyediting.
Problem: The central comparison between RDE-HRCD and StreamCat-NLCD is not apples-to-apples. The approaches differ in hydrography, corridor width, land-cover resolution, temporal window, and class definitions.
Why it matters: When methods differ simultaneously on several dimensions, similarity or difference in annualized totals cannot be interpreted cleanly as methodological agreement or disagreement.
Recommendation: The authors should either harmonize the comparison as far as possible, for example with matched extents, years, and class mappings, or reframe the exercise as an illustrative contrast rather than a quasi-validation.
Problem: Uncertainty is acknowledged, but it is not quantified in the reported results. The HRCD workflow uses quartile assignments and sampling decisions that introduce uncertainty, and the manuscript later notes residual error and possible upward bias from partial polygon intersections.
Why it matters: The main estimates are presented as point values without confidence intervals, sensitivity bounds, or propagated error. That makes it difficult to assess robustness.
Recommendation: The authors should provide quantitative uncertainty analysis, at minimum sensitivity bounds for change-category assignment, intersection assumptions, and comparison of alternative summarization rules.
Problem: Key claims about concentration within UGAs and salmon-associated reaches are descriptive only.
Why it matters: The patterns may be real, but the manuscript does not test whether they remain strong after controlling for reach area, county, hydrographic density, or western versus eastern Washington.
Recommendation: The authors should add formal quantitative analysis, for example effect sizes with confidence intervals, stratified comparisons, or a regression/permutation framework using reach area and relevant covariates.
Problem: The manuscript uses shifting spatial denominators and extents, especially for the 2021 status analysis. The methods describe extraction within RMZ and EOW polygons, the results discuss non-floodplain polygons in western Washington, and Table 2 is labeled RMZ+EOW extents.
Why it matters: These shifts make it hard to know exactly what area each percentage refers to, and they complicate interpretation across tables, figures, and narrative text.
Recommendation: The authors should define each analytical extent once, use a consistent notation throughout, and include a schematic or formula for every denominator used in percentages and ratios.
Problem: The treatment of “semi-pervious” HRCD change versus “medium/high intensity urban” NLCD classes is conceptually underdeveloped.
Why it matters: These are not equivalent constructs. Combining them into annualized totals can create misleading impressions of agreement.
Recommendation: The authors should justify the class crosswalk explicitly, show alternative summaries with and without semi-pervious areas, and state clearly what ecological process each class is meant to represent.
Problem: The 2021 CCAP standing-cover analysis is useful, but the manuscript does not present independent validation for this product within the study domain.
Why it matters: Because the CCAP layer supports one of the headline UGA findings, readers need some indication of accuracy or at least consistency against an internal benchmark.
Recommendation: The authors should validate the 2021 standing impervious layer against a sample of image-interpreted sites, or compare it to an independent high-resolution reference within representative counties.
Problem: The discussion overreaches from observational geospatial patterns to regulatory adequacy and “no net loss” implications. The manuscript itself notes that many assessed areas were outside operative local riparian jurisdiction during the time window.
Why it matters: This makes some policy conclusions stronger than the design can support. The data show spatial patterns of impervious cover change, not direct regulatory performance.
Recommendation: The authors should narrow the causal and policy language, separating what is directly shown from what remains a hypothesis or management implication.
Problem: Reproducibility is incomplete. The manuscript provides useful data links and a code link, but the supplementary material is still marked “TBD,” and the methods omit operational details needed to reproduce the exact outputs.
Why it matters: This is a data-rich geospatial study. Readers should be able to reconstruct the analytical workflow, including versioning, filters, joins, and summarization choices.
Recommendation: The authors should finalize the supplement, archive code in a stable release, and provide a reproducibility appendix covering software versions, parameter settings, and data snapshots.
Problem: The figures are central to the paper, but several are difficult to read at journal scale, especially the multi-panel statewide maps and the distribution plots.
Why it matters: When the visual evidence carries much of the argument, limited legibility directly weakens interpretation.
Recommendation: The authors should enlarge labels, simplify panels, state key numerical takeaways in captions, and consider moving some county-level maps or supplementary versions to higher-resolution appendices.
Problem: The reference list and end matter need major repair. Numbering is corrupted, some entries are inconsistently formatted, and front-matter placeholders plus “Supplementary Materials: TBD” remain in the draft.
Why it matters: This affects credibility and makes it difficult to evaluate the scholarship cleanly.
Recommendation: The authors should rebuild the reference list from the source manager, verify every citation-number mapping, and remove all production placeholders before resubmission.

Comments on the Quality of English Language

I think the English needs professional editing before publication. The underlying ideas are understandable, but the prose is presently compromised by uncorrected revision artifacts and inconsistent sentence construction.

Examples:

“Riparian ecosystems provide numerous services butthat are critical...” should be revised to “Riparian ecosystems provide numerous services that are critical...”
The sentence about high-resolution datasets capturing smaller changes is duplicated in the abstract and should appear once.
“Attention toAddressing this ongoing change will beis critical...” should be rewritten as a single clean sentence.

Author Response

Major comments

Problem: The manuscript is not in publication-ready prose. Numerous sentences contain visible editing artifacts, duplicated phrases, broken word joins, and unresolved revision text in the abstract, introduction, discussion, and conclusions.
Why it matters: This is not a cosmetic issue. It impairs meaning, makes several claims ambiguous, and raises concern that scientific statements may also not have been fully stabilized.
Recommendation: The authors should fully clean the manuscript before further review, then re-check every section for internal consistency after copyediting.

We apologize for this unfortunate situation, as we were unaware that reviewers would receive a version of the manuscript with edits still shown. This is the first instance in which what we considered an initial submission has gone to a first review with “track changes” evident, and we certainly would have avoided this had we been aware that it would happen.

Problem: The central comparison between RDE-HRCD and StreamCat-NLCD is not apples-to-apples. The approaches differ in hydrography, corridor width, land-cover resolution, temporal window, and class definitions.
Why it matters: When methods differ simultaneously on several dimensions, similarity or difference in annualized totals cannot be interpreted cleanly as methodological agreement or disagreement.
Recommendation: The authors should either harmonize the comparison as far as possible, for example with matched extents, years, and class mappings, or reframe the exercise as an illustrative contrast rather than a quasi-validation.

Thank you for this feedback. We agree that the comparative presentation warranted refinement. Our original intent in including the Streamcat-NLCD information was precisely to provide an “illustrative contrast” rather than a detailed comparative analysis and validation. We have revised throughout to better convey the role of these coarser national data as an aid to thinking about the strengths and limitations of the “best available” high resolution data (rather than as a corroboration or directly comparable resource).

Problem: Uncertainty is acknowledged, but it is not quantified in the reported results. The HRCD workflow uses quartile assignments and sampling decisions that introduce uncertainty, and the manuscript later notes residual error and possible upward bias from partial polygon intersections.
Why it matters: The main estimates are presented as point values without confidence intervals, sensitivity bounds, or propagated error. That makes it difficult to assess robustness.
Recommendation: The authors should provide quantitative uncertainty analysis, at minimum sensitivity bounds for change-category assignment, intersection assumptions, and comparison of alternative summarization rules.

Thank you for this feedback. We agree that adequately conveying uncertainty is essential, and we have contemplated various options in this manuscript given the aim of using existing public datasets for which some error sources were practically unquantifiable (e.g., hydrographic dataset positional error). This consideration contributed to our choice to describe the qualitative factors presented in Table 3, as our experience at the science-policy interface has shown that this type of information may be well received (indeed, sometimes better than statistical characterizations). Nonetheless, the description of HRCD processing has been increased substantially in L199-242 and the internal protocol manuals could also be cited if desired. We have noted the nature of these data as the type of high quality, high accuracy observations used for training or validation in other studies and products. In addition, we have revised the description of possible effects related to partial polygon intersections with lower quartile change proportions. We have also conducted bootstrap analyses to generate distributions for the total RDE-HRCD change estimates, recalculating the sum over the reach set after 1) a standard resampling with replacement and after 2) multiplying the observed value for each reach with a non-zero impervious increase by a random draw from a uniform distribution ranging from 0 to 2, as coefficients representing a range of ‘true’ change from none to double. These approaches do yield typical normal distributions for the statewide point estimates, but the first involves the inappropriate implicit assumption that the specific locations of individual changes are substitutable, while the errors imposed in the second are not meaningfully linked with the true sources of measurement error in the individual geographic observations. Consequently, we chose not to include them, even as supporting information. Although we think the revised manuscript adequately couches its claims, we would consider other specific proposals for additional analyses to perform.

Problem: Key claims about concentration within UGAs and salmon-associated reaches are descriptive only.
Why it matters: The patterns may be real, but the manuscript does not test whether they remain strong after controlling for reach area, county, hydrographic density, or western versus eastern Washington.
Recommendation: The authors should add formal quantitative analysis, for example effect sizes with confidence intervals, stratified comparisons, or a regression/permutation framework using reach area and relevant covariates.

Thank you for this feedback. We appreciate the interest in a more quantitatively sophisticated study. We have not added further modeling or analyses in these revisions, however, because this work was undertaken with the aim of providing a valid but quantitatively basic characterization of major patterns relevant to and approachable by a less technical audience. A more sophisticated modeling exercise exploring correlations (or even attempting to infer causality via econometric tools) was beyond the present scope, and we have clearly acknowledged this limitation (L507-517). In addition, we have removed all references to the work as an “analysis”, replacing with the term “assessment” to reduce the implicit suggestion of a quantitative extensive modeling effort.

Problem: The manuscript uses shifting spatial denominators and extents, especially for the 2021 status analysis. The methods describe extraction within RMZ and EOW polygons, the results discuss non-floodplain polygons in western Washington, and Table 2 is labeled RMZ+EOW extents.
Why it matters: These shifts make it hard to know exactly what area each percentage refers to, and they complicate interpretation across tables, figures, and narrative text.
Recommendation: The authors should define each analytical extent once, use a consistent notation throughout, and include a schematic or formula for every denominator used in percentages and ratios.

Thank you for noting this source of potential confusion. We have attempted to revise terms and labeling for greater clarity.

Problem: The treatment of “semi-pervious” HRCD change versus “medium/high intensity urban” NLCD classes is conceptually underdeveloped.
Why it matters: These are not equivalent constructs. Combining them into annualized totals can create misleading impressions of agreement.
Recommendation: The authors should justify the class crosswalk explicitly, show alternative summaries with and without semi-pervious areas, and state clearly what ecological process each class is meant to represent.

Thank you for this suggestion. We agree that the various NLCD “urban” or “developed” classes are not directly comparable with the HRCD impervious and semi-pervious change measures (see also previous response regarding the broader revision to clarify the coarser national data as illustrative constrast). We have presented estimates separately in revised Table 2 and Figure 3 and removed annualized values.

Problem: The 2021 CCAP standing-cover analysis is useful, but the manuscript does not present independent validation for this product within the study domain.
Why it matters: Because the CCAP layer supports one of the headline UGA findings, readers need some indication of accuracy or at least consistency against an internal benchmark.
Recommendation: The authors should validate the 2021 standing impervious layer against a sample of image-interpreted sites, or compare it to an independent high-resolution reference within representative counties.

Thank you for this feedback. Our manual inspection of these data has suggested that they are highly accurate relative to imagery, but we are not clear how this recommendation could be plausibly implemented within the scope of the manuscript (other than perhaps by including an additional figure as supporting information?). Is there a specific suggestion for “an independent high-resolution reference”?

Problem: The discussion overreaches from observational geospatial patterns to regulatory adequacy and “no net loss” implications. The manuscript itself notes that many assessed areas were outside operative local riparian jurisdiction during the time window.
Why it matters: This makes some policy conclusions stronger than the design can support. The data show spatial patterns of impervious cover change, not direct regulatory performance.
Recommendation: The authors should narrow the causal and policy language, separating what is directly shown from what remains a hypothesis or management implication.

Thank you for noting these concerns. The policy implications and applications have been tightened to ensure alignment with the evidence. Several statements that might have been interpreted as more speculative have been removed. We note that both the previous and revised manuscript were careful to acknowledge that the observed increases do not measure “direct regulatory performance”, given our recognition that such measurement would be extremely difficult if not impossible over even a sub-regional extent.

Problem: Reproducibility is incomplete. The manuscript provides useful data links and a code link, but the supplementary material is still marked “TBD,” and the methods omit operational details needed to reproduce the exact outputs.
Why it matters: This is a data-rich geospatial study. Readers should be able to reconstruct the analytical workflow, including versioning, filters, joins, and summarization choices.
Recommendation: The authors should finalize the supplement, archive code in a stable release, and provide a reproducibility appendix covering software versions, parameter settings, and data snapshots.

Thank you for this recommendation. We fully agree on the importance of transparency and reproducibility, especially for research in the public interest. We apologize for the “TBD” oversight, and we will plan to provide adequate scripting materials pending acceptance and finalization.

Problem: The figures are central to the paper, but several are difficult to read at journal scale, especially the multi-panel statewide maps and the distribution plots.
Why it matters: When the visual evidence carries much of the argument, limited legibility directly weakens interpretation.
Recommendation: The authors should enlarge labels, simplify panels, state key numerical takeaways in captions, and consider moving some county-level maps or supplementary versions to higher-resolution appendices.

We have revised and enlarged elements of all figures and will provide full size versions outside of the journal Word template.

Problem: The reference list and end matter need major repair. Numbering is corrupted, some entries are inconsistently formatted, and front-matter placeholders plus “Supplementary Materials: TBD” remain in the draft.
Why it matters: This affects credibility and makes it difficult to evaluate the scholarship cleanly.
Recommendation: The authors should rebuild the reference list from the source manager, verify every citation-number mapping, and remove all production placeholders before resubmission.

Again, we apologize for what seems to have been a production error in the editorial system, and we believe we have revised the document template elements in our control.

Round 2

Reviewer 4 Report

Comments and Suggestions for Authors

I can confirm that the authors have indeed addressed my previous concerns and implemented the requested revisions. I am now satisfied with the methodological clarifications and the adjustments made.

Comments for author File: Comments.pdf

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High-Resolution Assessment of Riparian Impervious Cover Across Watersheds to Inform Land Use Policy and Management

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