May 15, 2017

May 15, 2017

Honorable Kimberly D. Bose Secretary

Federal Energy Regulatory Commission

888 First Street, NE

Washington, DC 20426


Re:     Wilder Dam Project No. 1892

Bellows Falls Project No. 1855

Vernon Dam Project No. 1904

Connecticut River Conservancy Comments on Great River Hydro, LLC Study Reports filed by March 15, 2017; Request for Study Modification to Require Compliance with the RSP. 


Dear Secretary Bose,

The Connecticut River Watershed Council, Inc. (CRWC), now doing business as the Connecticut River Conservancy (CRC), is a nonprofit citizen group established in 1952 to advocate for the protection, restoration, and sustainable use of the Connecticut River and its four-state watershed.  We have been participating in the relicensing of the five hydropower facilities on the Connecticut River since the beginning of the process in late 2012.  We have reviewed the set of Study Reports that were posted by TransCanada by March 15, 2017.  CRC attended the study report meeting held on March 30, 2017.  In April, the licenses for the TransCanada facilities were transferred to a new owner, Great River Hydro, LLC.  Below are our comments.  CRC again hired Princeton Hydro to conduct a peer review of the revised ILP Study 2 and Study 3 Riverbank Transect and Riverbank Erosion Studies, and their review is attached to this comment letter.

Revised ILP Study 2 and Study 3:  Riverbank Transect and Riverbank Erosion Studies dated 2/4/2017

Comments based on peer review

CRC hired consulting engineering firm Princeton Hydro ( to conduct a peer review of this revised study report.  Based on the peer review, CRC continues to believe that Studies 2-3 were conducted: (1) in violation of the Revised Study Report (RSP) dated August 14, 2013 and approved with modifications from FERC on September 13, 2013; (2) did not follow several recommendations from FERC’s Determination on Requests for Study Modifications and New Studies dated November 29, 2016 (“FERC Determination”), (3) failed to rely on generally accepted scientific methods; and/or (4) otherwise reached conclusions that the science, data or evidence do not support.  The revised study report fails to comply with the RSP and/or the FERC determination in the following ways:

  • The FERC determination stated that TransCanada would use HEC-RAS modeling in combination with logistic regression statistical analysis at the 21 detailed monitoring sites. Great River Hydro’s revised study report did not include a logistical regression analysis on the 21 detailed monitoring sites.  Moreover, stakeholders were not provided with any sheer stress data, nor information how it might have been generated.  This runs counter to what TransCanada said they would do in their response to comment document dated October 31, 2016, responding to comment #3: “Shear stress analysis (a function of velocity) will be presented in a manner similar to WSE fluctuations.”
  • Princeton Hydro’s peer review identifies a number of problems with the regression analysis. One, as identified in Appendix E, is that the regression analysis assumes observations are independent variables.  Some of the results of the statistical analysis led to counter-intuitive results or inconclusive results, and the value of the analysis is therefore questionable.
  • The FERC determination recommends that the revised report should include additional information that describes how the hydraulic gradients were calculated and the resulting potential for riverbank erosion. The discussion should include any discussion of observation of groundwater seeps or groundwater elevation data collected during the studies.  No groundwater data, and thereby no hydraulic gradient data for the streambank were collected or analyzed.
  • The FERC determination recommended that the revised study report contain a detailed, qualitative discussion of the potential effects of ongoing erosion on other resources, with the discussion including comparative maps and site-specific observations. Few maps or qualitative assessments were included in the revised report.

To remedy these shortcomings, CRC summarizes some of Princeton Hydro’s recommendations below:

  • Great River Hydro should conduct a sheer-stress and velocity analysis using the one-dimensional HEC-RAS model to identify the likely causes of erosion at the 21 erosion monitoring sites. Great River Hydro should provide input and output data, as well as the HEC-RAS model itself, to facilitate review by stakeholders.
  • The input data used for the regression analysis should be evaluated for spatial autocorrelation and dependencies as recommended in Princeton Hydro’s attached peer review. If significant, an alternative statistical test should be completed.  Regression analysis should be completed on the data set related to the 21 transects.
  • Great River Hydro should collect groundwater elevation data and observations of groundwater seeps or seepage-related erosion at the 21 monitored transects. Great River Hydro should analyze that data to determine how operational water surface elevation (WSE) fluctuations potentially affect streambank stability.
  • Great River Hydro should include additional mapping as stated in the peer review, and further assessment of potential impacts of ongoing bank erosion and release of fine sediments to the river channel to cobblestone tiger beetle habitat, water quality impacts related to sight-feeding and respiration of fish, aquatic habitat and substrate, spawning of riverine fishes, and freshwater mussels.

Additional CRC comments

  1. There were numerous problems associated with the regression analysis, explained in the following comments.
    1. We do not understand why TransCanada chose to perform regression analysis on the 124-mile dataset of bank characteristics when the FERC determination and Princeton Hydro’s first peer review recommended regression analysis on the 21 detailed study sites. Even TransCanada acknowledged weaknesses with this dataset in October in response to comment #53: “This does not discount that certain areas may be particularly sensitive to changes, but the data set collected along 250 mi of bank is not refined enough to characterize all of the potential driving forces and resisting forces acting on the bank at any particular point.”
    2. The study report stresses repeatedly how important sediment characteristics are (see quotes included in the peer review letter on page 6). Yet sediment characteristics weren’t included in the regression analysis at all, because the data set given to the statistician didn’t include that information.  It is part of the 21 study sites, and again we are unclear why the regression analysis wasn’t performed on the data set associated with the 21 sites.
    3. The regression analysis used sheer stresses for two cases only: Case 1 at “low flow,” which was described as the high end of project operational flows.  Case 2 was “high flow” or the approximate 10-year recurrence interval flows.  CRC is unclear what flows were used for each case at each project.  At Wilder, for example, Table 6.1-1 footnote “a” states that the maximum Wilder station discharge with all three units operating is approximately 11,700 cfs.  However, Table 5.8-1 displayed velocities at the 13 impoundment sites using 10,000 and 16,000 cfs.  CRC is not sure what flows were used in the regression analysis and how this compares to the velocities used in the table shown in the report.  We also point out that it appears that no velocities or sheer stresses looked at operational flows other than the highest operational flow.  The range of flows under project operations was not assessed.
    4. In our comment letter dated September 30, 2016, CRWC had recommended that TransCanada should re-evaluate the existing data with regard to factors such as land use on the impacts of water level fluctuations on erosion. TransCanada’s response #36 stated, “We note that the Study 2 study plan was related to the 21 monitoring sites only, not to the entire river within the study area, which was the topic of Study 3.  While the report for both studies was consolidated, the goals and objectives for each study differed.  Effort was made to determine the relative importance of various factors through the use of the erosion ratio.  A determination of groundwater levels and careful mapping of all land uses along the river were beyond the scope of the study.”  Nevertheless, Appendix E indicates that forest vegetation contributes only a small amount in explaining erosion deviance.  We are once again confused why TransCanada did not use the data set for the 21 study sites in its logistic regression analysis, because these sites had a more detailed analysis of land use and riparian cover.
  2. Use of the Erosion Ratio

Princeton Hydro’s peer reviews have noted potential biases in the use of the erosion ratio and that it is not generally accepted scientific practice.  TransCanada in their 10/31/2016 responses to comments noted in several places that the erosion ratio was used in the 2007 fluvial geomorphology study of the Turners Falls impoundment and that this study was accepted by FERC and no stakeholders objected to its use at that time.  CRC, as one of the stakeholders involved in reviewing the 2007 Field study, would like to point out that the 2007 study was conducted in response to a FERC order dated June 28, 2005 that the owner Northeast Generation Company (called Northeast) “…submit a plan of action by which Northeast will be able to show a reduction in the rate of erosion of the shoreline of the Turners Falls Pool by the next scheduled river reconnaissance.”  Instead of submitting a plan, the owner of Northfield Mountain Pumped Storage Project (P-2485) hired Field Geology Services to conduct the fluvial geomorphology study.  The study produced some useful observations and recommendations, and stakeholders were generally pleased with the quality of the work (but displeased that the study never resulted in the required “plan”).  The erosion ratio was included in a single column in a single table, and had no bearing on the overall purpose of the report.  Therefore, the lack of comments should not be inferred as an agreement with the methodology of that single column—reviewers paid no attention to it, and focused comments on other elements of the study.

  1. Operation Trends

CRWC’s comment letter dated September 29, 2016, recommended that TransCanada “revise the report to add data supporting their claim that ‘normal project operations have changed little in several decades’ that appears in the last paragraph in the report.”  In TransCanada’s Response to Comments document dated October 31, 2016, the response to comment #37, TransCanada stated, “The revised report will provide additional information to support our claim that operations have changed little in several decades.”  Section 6.3 Historic Trends in Project Operations has been added in this revised study report.  In this section, TransCanada provided exceedance curves for impoundment elevations at midnight for 3 sample 10-year operating periods at the three dams.  This section actually indicates that project operations have changed, and provides explanations for these changes.

Of interest is that the 50% exceedance of Wilder impoundment elevation at midnight has increased by 6 inches in the recent decade compared to previous decades.  This corresponds with landowner concerns that the river is being held at higher elevations than in the past, submerging beaches that had been exposed in the past.  As we have learned with other projects on the Connecticut River, such as the Turners Falls impoundment, changes in the daily “average” water level can destabilize repaired banks.

CRC would like to add that exceedance curves for midnight readings do not capture the full scope of “normal operation of the station generation and impoundment storage.”  There is more to project operations than a midnight elevation of the impoundment.  In particular, in the past decade, we have seen deregulation of the electric industry, sales of hydropower assets to international companies and investment firms, and retirement of some of the larger coal and nuclear power plants in the region.  The changing energy market could result in more hydropower peaking and therefore higher sub-daily fluctuations of impoundments or multiple peaks per day.  The report contains no information on trends in operations leading to sub-daily changes, and TransCanada states on page 133 (also stated at the March 30 meeting) that to provide this information would be a time-consuming process converting paper logs sheets to electronic data.

  1. WSE Fluctuations

Appendix A contained river stage profiles for the 21 transects, showing the median WSE fluctuation zone compared to the river bank profile.  Table 4 in Appendix E shows the bins of the median fluctuation ranges.  It is notable that though the report often states how project operations result in a fairly narrow fluctuation range, data in Table 4 of Appendix E show that the riverbank lengths associated with median fluctuations of between 4 and 7 ft add up to 193,803 ft or 36.7 miles of bank.

TransCanada provided logger data to stakeholders, which helps us understand the nature of river fluctuations better than exceedance curves or shaded bands on a bank.  The graphs below have been made using the WSE logger data provided by TransCanada that were installed for Study 2 and 3, using one site for example purposes.  The graphs show how water levels at the Wilder impoundment transect site, Mudge W09, varied in August and October 2015.  In August, the river elevations varied between 383 and 385.5 ft, whereas in October, the river elevations never exceeded 384.5 ft, with two peaks per day being common.  It also appears that midnight is a time when the river levels are steeply rising, as the impoundments are being re-filled to get ready for the next day’s generation period.  Below each graph shows the USGS gage for the corresponding month at the Wells River, VT site, approximately 50 miles upstream of the Wilder Dam but downstream of the next upstream dam (Ryegate Dam).

CRC recommendation

The TransCanada RSP for Study 2 stated that, “Relationships observed between changing water levels and the timing of bank erosion will help establish whether water-level fluctuations, described in terms of magnitude, periodicity and duration, and increased shear stresses resulting from project operations are correlated with erosion in project-affected areas.”  Overall, Great River Hydro has provided information indicating that high flow events are the dominant cause of erosion along the banks of the Connecticut River impacted by the operation of Wilder, Bellows Falls, and Vernon Dams.  However, project operational effects have mostly gone unassessed.  If you examine the graphs provided below, CRC maintains that the operation of the dams cause river fluctuations that are far from that of a natural river.  The study report has looked at the magnitude of water level fluctuations, but not the periodicity and duration of water level fluctuations, and sheer stresses from project operations have only been looked at for the upper end.  Sub-daily fluctuations will undoubtedly have some effect on bank stability, and it may not be entirely due to changes in sheer stress.  Our understanding of the degree of influence of these fluctuations has not been appreciably advanced by this study.  CRC requests that these studies be modified pursuant to 18 C.F.R. § 5.15(a) and (d) (1) to fully address these comments.  In lieu of fixing the problems with the study, we may also need to just proceed with a gap in understanding.  To the extent possible we will recommend operational changes to reduce river fluctuations, and in lieu of that we will be recommending elements of a plan to mitigate the impact of project operations.

ILP Study 25:  Dragonfly and Damselfly Inventory and Assessment

The study uses 30 minutes for assessing project impacts on dragonfly eclosure, based on a literature review.  Using an eclosure period of 30 minutes seems to be too short a time span.  The FirstLight dragonfly study used a critical duration of 2 hours in their risk assessment.  CRC recommends Great River Hydro consider using a longer eclosure period to be consistent with the FirstLight report.

The study used logger data to assess impacts from water elevation increases during the 30-minute eclosure period.  The logger data were collected every 15 minutes and the hydraulic model data is hourly.  Showing an accurate river elevation rate of change for 30 minutes would be difficult with the available data.  Again, CRC recommends that Great River hydro use a longer eclosure period, such as 1-2 hours.


It seems that to assess project effects, the study should look at the height of water surface elevation (WSE) change over the critical time period (30 minutes in this study, but CRC would prefer 1-2 hours) and compare that with the typical distance above water that eclosure takes place.  Despite the habitat elevations and hourly WSE’s in figures in the report, we could not find information that would help us understand the amount of change in a 30-min, 1-hour, or 2-hour period.  For example, on page 20 it states that, “The mean vertical distance from the water surface at which eclosing Stylurus spiniceps were observed was 12 inches (range of 8-16 inches).”  What is the likelihood in the study areas that the water level would rise by 12 inches in the span of 30 minutes, 1 hour, or 2 hours?

We appreciate the opportunity to provide comments on the studies submitted by March 15, 2017.  I can be reached at or (413) 772-2020 x.205.



Andrea F. Donlon

River Steward


ATTACHMENT:  Princeton Hydro peer review dated May 15, 2017