All the criteria mentioned in the following list are defined specifically in relation to hydropower dams. This list is non-exhaustive; it does not include all decision criteria that may be important to all people. For example, in some situations, it may be important to include additional animal species, community economic impact, demand for whitewater and/or flatwater recreation, jobs, water quality (could use existing state water quality standards), etc. For decision criteria that are included, many criteria could be unpacked into different sub-criteria (e.g., species-specific habitat area (e.g., Atlantic salmon only, or Alewife only), different uses for reservoir storage such as drinking water or fire suppression). The criteria identified in this list are representative of current issues important to dam decision making as expressed by stakeholders in interview.
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Variable |
Units |
Equation |
Description |
Source |
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Sea-run fish habitat area |
100 square meters |
 |
A proxy criteria estimated as possible upstream sea-run fish (Atlantic salmon, Alewife, Blueback herring, American eel) functional habitat (Roy et al., 2018). |
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River recreation area |
Square kilometers |
 |
Estimated downstream area of river that may increase or decrease with a dam decision alternative, represents functional area for whitewater recreation defined by Roy et al. (2018). |
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Reservoir storage |
100,000 acre-feet |
 |
Estimated storage potential of the reservoir, based on its volume (Roy et al., 2018). |
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Breach Damage Potential |
unitless |
 |
A proxy for safety based on the State hazard rating, which indicates the potential for downstream property damage, injury, and death in the case of dam breach (Roy et al., 2018). |
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Properties Impacted |
Number of properties |
 |
Estimated number of properties impacted by the decision alternative, based on potential changes in viewshed or property value (Roy et al., 2018). |
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Annuitized Cost Keep and Maintain |
2019 USD/ year |
Annuitized Cost Keep & Maintain = O&M |
Annual O&M costs assuming no capital costs and minimum safety requirements for keeping and maintaining a project, making this the status quo option. Estimated as a percentage of total capital cost (O’Connor et al., 2015). |
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Annuitized Cost for Improve Hydro |
2019 USD/ year |
Annuitized Cost Improve Hydro = CAPEX Hydro*((0.062)*(1+0.062)^20)/(((1+0.062)^20)-1)+O&M |
Annuitized cost (annual cost of the project over its lifetime) of improving hydropower generation at a project (equation comes from NREL, 1995 report), assumes a 20-year lifetime and 6.2% discount rate (O'Connor et al. 2015). |
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Annuitized Cost for Improve Fish |
2019 USD/ year |
Annuitized Cost Improve Fish = (CAPEX Fish+((1300000*Capacity)^0.56))*((0.062)*(1+0.062)^20)/(((1+0.062)^20)-1)+O&M |
Annuitized cost (annual cost of the project over its lifetime) of improving hydropower generation at a project (equation comes from NREL, 1995 report), assumes a 20-year lifetime and 6.2% discount rate (O'Connor et al. 2015), and includes an annuitization of the 30-year lifetime cost of fish passage mitigation for threatened and endangered species (Hall et al., 2003), plus O&M. |
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Annuitized Cost for Improve Fish AND Hydro |
2019 USD/ year |
Annuitized Cost Fish & Hydro = ((CAPEX Fish+CAPEX Hydro)+((1300000*Capacity)^0.56))*((0.062)*(1+0.062)^20)/(((1+0.062)^20)-1)+O&M |
Annuitized cost - annual cost of a project over its lifetime. Here, we use the sum of capital cost for improved hydro and fish passage, assuming a 20-year lifetime and 6.2% discount rate (O'Connor et al. 2015) and including an annuitization of the 30-year lifetime cost of fish passage mitigation for threatened and endangered species (Hall et al., 2003), plus O&M. |
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Annuitized Cost for removal |
2019 USD/ year |
Annuitized Cost Removal = CAPEX Remove*((0.062)*(1+0.062)^20)/(((1+0.062)^20)-1)+O&M |
Cost of removing the dam, annually over a period of 20 years (equation comes from NREL, 1995 report), assumes a 6.2% discount rate (O'Connor et al. 2015). |
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Average Annual Electricity Generation Hydro Improve |
GWh/year |
N/A |
Licensee-reported average annual electricity generation - gigawatthours of electricity generated annually at a particular dam site, averaged from 2015 - 2018 (Brookfield report to FERC). Penobscot Mills sites, average electricity generation reported on the FERC license was used. |
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Potential Additional Generation (kWh) |
GWh/year |
N/A |
Potential additional average annual electricity generation - kilowatt hours of electricity generate annually in addition to whatever is already being generated at a particular dam site. Calculated using potential additional capacity estimate (from 2015 Maine Hydropower Study, these were selected using the MEMA database of Maine dams) multiplied by the capacity factor over 24 hours/day for a year. |
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Annual CO2 Emission reduction |
metric kilotonnes |
Annual emissions reduction = 0.196*annual generation |
Estimate of avoided carbon dioxide emissions from annual hydropower-generated electricity production (reservoir or diversion-design dams); based on decreasing generation from the State's electricity generation mix; includes life cycle emissions impacts.Where dams are diversion-style, 0.142 is used as the GHG emissions avoided (kgCO2eq/kWh) value. |
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Annual Additional CO2 Emission reduction |
metric kilotonnes |
Annual emissions reduction = 0.196*annual generation |
Estimate of avoided carbon dioxide emissions from annual hydropower-generated electricity production (reservoir or diversion-design dams); based on decreasing generation from the State's electricity generation mix; includes life cycle emissions impacts. Where dams are diversion-style, 0.142 is used as the GHG emissions avoided (kgCO2eq/kWh) value. |
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We collected data on the following decision criteria as a part of a targeted pre-survey effort, prior to a participatory workshop held in October 2019, with real dam decision makers in Maine. While we engaged participants in defining the social criteria data values for the version of the Dam Decision Support Tool used in the October 2019 workshop, we ultimately decided to leave the data values blank in the final version of the Dam Decision Support Tool published online (except for Indigenous Cultural Traditions and Lifeways, the values from which come from a survey of Penobscot Nation citizens (N=2), supported by informal conversations with Penobscot Nation citizens and representatives. Future studies could improve on these data by surveying a greater number of tribal citizens, but for public release we deemed it important to include real values for this criterion, however small the survey sample).
For future work involving these ‘social’ or qualitative decision criteria, we recommend surveying a broader population than the users of the Dam Decision Support Tool. Directions for the multiple-choice (1 - 5) survey questions we crafted are as follows: “You will be asked to consider several dam projects coming up for Federal Energy Regulatory Commission (FERC) relicensing in the Penobscot River Watershed: Medway Dam, Ripogenus Dam, West Enfield Dam, and the Penobscot Mills Project (also referred to as Great Northern Paper Mill and including 5 dams: Millinocket/Quakish, East Millinocket, North Twin, Dolby, and Millinocket Lake). During any relicensing process, the hydropower operation license application is opened to public comment, water quality certifications are issued, and federal and state agencies submit formal opinions about the operation of the dam. For each of the questions here, you will rate a series of decision criteria (i.e., attributes or issues related to dams) for a specific dam. You will be asked about possible options for the dam, based on your prior knowledge of the dam site. PLEASE USE YOUR PERSONAL AND/OR PROFESSIONAL EXPERIENCE TO HELP YOU ANSWER THESE QUESTIONS - you are not representing your entity in the same way you were in questions 7-8. Draw on ANY personal and/or professional experience you have to answer these questions.”
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Variable |
Description |
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Aesthetics_KeepMaintain |
Rating to convey the importance of improving or preserving aesthetics (e.g., appearance, scenic value, smell, sound) at a dam site. Survey Question: consider each option (e.g., remove dam, improve hydropower generation) one at a time. What do you think the state of AESTHETICS would be at the MEDWAY DAM site if the decision alternative happened? For example, if you think the aesthetics of the existing dam are good, you would select a high rating (4 -5) for "keep and maintain dam". If you think the aesthetics would be greatly improved by removing the dam, you would select a high rating for "remove dam". |
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Aesthetics_Remove |
Rating to convey the importance of improving or preserving aesthetics (e.g., appearance, scenic value, smell, sound) at a dam site. Survey Question: consider each option (e.g., remove dam, improve hydropower generation) one at a time. What do you think the state of AESTHETICS would be at the MEDWAY DAM site if the decision alternative happened? For example, if you think the aesthetics of the existing dam are good, you would select a high rating (4 -5) for "keep and maintain dam". If you think the aesthetics would be greatly improved by removing the dam, you would select a high rating for "remove dam". |
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Aesthetics_ImproveHydro |
Rating to convey the importance of improving or preserving aesthetics (e.g., appearance, scenic value, smell, sound) at a dam site. Survey Question: consider each option (e.g., remove dam, improve hydropower generation) one at a time. What do you think the state of AESTHETICS would be at the MEDWAY DAM site if the decision alternative happened? For example, if you think the aesthetics of the existing dam are good, you would select a high rating (4 -5) for "keep and maintain dam". If you think the aesthetics would be greatly improved by removing the dam, you would select a high rating for "remove dam". |
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Aesthetics_ImproveFish |
Rating to convey the importance of improving or preserving aesthetics (e.g., appearance, scenic value, smell, sound) at a dam site. Survey Question: consider each option (e.g., remove dam, improve hydropower generation) one at a time. What do you think the state of AESTHETICS would be at the MEDWAY DAM site if the decision alternative happened? For example, if you think the aesthetics of the existing dam are good, you would select a high rating (4 -5) for "keep and maintain dam". If you think the aesthetics would be greatly improved by removing the dam, you would select a high rating for "remove dam". |
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Aesthetics_FishANDHydro |
Rating to convey the importance of improving or preserving aesthetics (e.g., appearance, scenic value, smell, sound) at a dam site. Survey Question: consider each option (e.g., remove dam, improve hydropower generation) one at a time. What do you think the state of AESTHETICS would be at the MEDWAY DAM site if the decision alternative happened? For example, if you think the aesthetics of the existing dam are good, you would select a high rating (4 -5) for "keep and maintain dam". If you think the aesthetics would be greatly improved by removing the dam, you would select a high rating for "remove dam". |
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Town/City_KeepMaintain |
Rating to convey the importance of the dam for preserving the existing town/city identity for residents living along the river. Survey Question: consider each option (e.g., remove dam, improve hydropower generation) one at a time. How would you rate the sense of TOWN/CITY IDENTITY at the MEDWAY DAM site if an option happened? For example, if you think community identity is currently strongly linked to the existing dam, you would select a high rating (4 - 5) for "keep and maintain dam". If you think a free-flowing river at that site would contribute to a strong sense of community identity, you would select a high rating for "remove dam". |
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Town/City_Remove |
Rating to convey the importance of the dam for preserving the existing town/city identity for residents living along the river. Survey Question: consider each option (e.g., remove dam, improve hydropower generation) one at a time. How would you rate the sense of TOWN/CITY IDENTITY at the MEDWAY DAM site if an option happened? For example, if you think community identity is currently strongly linked to the existing dam, you would select a high rating (4 - 5) for "keep and maintain dam". If you think a free-flowing river at that site would contribute to a strong sense of community identity, you would select a high rating for "remove dam". |
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Town/City_ImproveHydro |
Rating to convey the importance of the dam for preserving the existing town/city identity for residents living along the river. Survey Question: consider each option (e.g., remove dam, improve hydropower generation) one at a time. How would you rate the sense of TOWN/CITY IDENTITY at the MEDWAY DAM site if an option happened? For example, if you think community identity is currently strongly linked to the existing dam, you would select a high rating (4 - 5) for "keep and maintain dam". If you think a free-flowing river at that site would contribute to a strong sense of community identity, you would select a high rating for "remove dam". |
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Town/City_ImproveFish |
Rating to convey the importance of the dam for preserving the existing town/city identity for residents living along the river. Survey Question: consider each option (e.g., remove dam, improve hydropower generation) one at a time. How would you rate the sense of TOWN/CITY IDENTITY at the MEDWAY DAM site if an option happened? For example, if you think community identity is currently strongly linked to the existing dam, you would select a high rating (4 - 5) for "keep and maintain dam". If you think a free-flowing river at that site would contribute to a strong sense of community identity, you would select a high rating for "remove dam". |
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Town/City_FishANDHydro |
Rating to convey the importance of the dam for preserving the existing town/city identity for residents living along the river. Survey Question: consider each option (e.g., remove dam, improve hydropower generation) one at a time. How would you rate the sense of TOWN/CITY IDENTITY at the MEDWAY DAM site if an option happened? For example, if you think community identity is currently strongly linked to the existing dam, you would select a high rating (4 - 5) for "keep and maintain dam". If you think a free-flowing river at that site would contribute to a strong sense of community identity, you would select a high rating for "remove dam". |
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Lifeways_KeepMaintain |
Rating to convey the importance of preserving or restoring the culture and practices of indigenous people at the dam site. Survey Question: consider each option (e.g., remove dam, improve hydropower generation) one at a time. How would you rate strengthening the practice of INDIGENOUS CULTURAL TRADITIONS and LIFEWAYS at the MEDWAY DAM site if the decision alternative happened? For example, if you think the practice of indigenous cultural traditions and lifeways are currently strongly supported by the existing dam, you would select a high rating (4 - 5) for "keep and maintain dam". If you think a free-flowing river at that site would strengthen the practice of indigenous cultural traditions and lifeways, you would select a high rating for "remove dam". |
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Lifeways_Remove |
Rating to convey the importance of preserving or restoring the culture and practices of indigenous people at the dam site. Survey Question: consider each option (e.g., remove dam, improve hydropower generation) one at a time. How would you rate strengthening the practice of INDIGENOUS CULTURAL TRADITIONS and LIFEWAYS at the MEDWAY DAM site if the decision alternative happened? For example, if you think the practice of indigenous cultural traditions and lifeways are currently strongly supported by the existing dam, you would select a high rating (4 - 5) for "keep and maintain dam". If you think a free-flowing river at that site would strengthen the practice of indigenous cultural traditions and lifeways, you would select a high rating for "remove dam". |
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Lifeways_ImproveHydro |
Rating to convey the importance of preserving or restoring the culture and practices of indigenous people at the dam site. Survey Question: consider each option (e.g., remove dam, improve hydropower generation) one at a time. How would you rate strengthening the practice of INDIGENOUS CULTURAL TRADITIONS and LIFEWAYS at the MEDWAY DAM site if the decision alternative happened? For example, if you think the practice of indigenous cultural traditions and lifeways are currently strongly supported by the existing dam, you would select a high rating (4 - 5) for "keep and maintain dam". If you think a free-flowing river at that site would strengthen the practice of indigenous cultural traditions and lifeways, you would select a high rating for "remove dam". |
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Lifeways_ImproveFish |
Rating to convey the importance of preserving or restoring the culture and practices of indigenous people at the dam site. Survey Question: consider each option (e.g., remove dam, improve hydropower generation) one at a time. How would you rate strengthening the practice of INDIGENOUS CULTURAL TRADITIONS and LIFEWAYS at the MEDWAY DAM site if the decision alternative happened? For example, if you think the practice of indigenous cultural traditions and lifeways are currently strongly supported by the existing dam, you would select a high rating (4 - 5) for "keep and maintain dam". If you think a free-flowing river at that site would strengthen the practice of indigenous cultural traditions and lifeways, you would select a high rating for "remove dam". |
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Lifeways_FishANDHydro |
Rating to convey the importance of preserving or restoring the culture and practices of indigenous people at the dam site. Survey Question: consider each option (e.g., remove dam, improve hydropower generation) one at a time. How would you rate strengthening the practice of INDIGENOUS CULTURAL TRADITIONS and LIFEWAYS at the MEDWAY DAM site if the decision alternative happened? For example, if you think the practice of indigenous cultural traditions and lifeways are currently strongly supported by the existing dam, you would select a high rating (4 - 5) for "keep and maintain dam". If you think a free-flowing river at that site would strengthen the practice of indigenous cultural traditions and lifeways, you would select a high rating for "remove dam". |
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History_KeepMaintain |
Rating to convey the importance of the dam for preserving/restoring the industrial history of the site. Survey Question: consider each option (e.g., remove dam, improve hydropower generation) one at a time. How would you rate the INDUSTRIAL HISTORICAL IMPORTANCE of the MEDWAY DAM site if the option happened? For example, if you think the existing dam holds a lot of industrial historical importance, you would select a high rating (4 - 5) for "keep and maintain dam". If you think a free-flowing river at that site would hold a lot of industrial historical importance, you would select a high rating for "remove dam". |
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History_Remove |
Rating to convey the importance of the dam for preserving/restoring the industrial history of the site. Survey Question: consider each option (e.g., remove dam, improve hydropower generation) one at a time. How would you rate the INDUSTRIAL HISTORICAL IMPORTANCE of the MEDWAY DAM site if the option happened? For example, if you think the existing dam holds a lot of industrial historical importance, you would select a high rating (4 - 5) for "keep and maintain dam". If you think a free-flowing river at that site would hold a lot of industrial historical importance, you would select a high rating for "remove dam". |
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History_ImproveHydro |
Rating to convey the importance of the dam for preserving/restoring the industrial history of the site. Survey Question: consider each option (e.g., remove dam, improve hydropower generation) one at a time. How would you rate the INDUSTRIAL HISTORICAL IMPORTANCE of the MEDWAY DAM site if the option happened? For example, if you think the existing dam holds a lot of industrial historical importance, you would select a high rating (4 - 5) for "keep and maintain dam". If you think a free-flowing river at that site would hold a lot of industrial historical importance, you would select a high rating for "remove dam". |
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History_ImproveFish |
Rating to convey the importance of the dam for preserving/restoring the industrial history of the site. Survey Question: consider each option (e.g., remove dam, improve hydropower generation) one at a time. How would you rate the INDUSTRIAL HISTORICAL IMPORTANCE of the MEDWAY DAM site if the option happened? For example, if you think the existing dam holds a lot of industrial historical importance, you would select a high rating (4 - 5) for "keep and maintain dam". If you think a free-flowing river at that site would hold a lot of industrial historical importance, you would select a high rating for "remove dam". |
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History_FishANDHydro |
Rating to convey the importance of the dam for preserving/restoring the industrial history of the site. Survey Question: consider each option (e.g., remove dam, improve hydropower generation) one at a time. How would you rate the INDUSTRIAL HISTORICAL IMPORTANCE of the MEDWAY DAM site if the option happened? For example, if you think the existing dam holds a lot of industrial historical importance, you would select a high rating (4 - 5) for "keep and maintain dam". If you think a free-flowing river at that site would hold a lot of industrial historical importance, you would select a high rating for "remove dam". |