Freshwater Resilient Connected Network 2024 (2 Class Display)

UPDATED VERSION 2024-09-26. (Previous version 2023-09-28). Note this 2024 version includes some additional sites based on dam removals and feedback received since the first release in 2023. Data Download: The flowlines and polygons representing the Freshwater Resilient and Connected Network are available as an ESRI File Geodatabase. DETAILED DESCRIPTION This Freshwater Resilient and Connected Network (FRCN) polygon area dataset represents the FRCN watershed areas (HUC12-FCN-biodiversity areas) that make up the FRCN. The FRCN can also be represented using the Freshwater Resilient and Connected Network (FRCN) flowline dataset to represent the network flowlines (streams, rivers, waterbody centerlines) that were within the FRCN watershed polygon areas. The FRCN polygon units were coded into nine classes that can be collapsed into five or just two simple classes by loading the appropriately named .lyrx file in ArcPro. The Freshwater Resilient and Connected Network (FRCN) is a key output of TNC's Freshwater Resilience Analysis and represents a subset of the higher scoring units analyzed. We defined "Freshwater Resilience" as the ability of a stream network or other aquatic setting to maintain biologic diversity even as the system changes in composition and structure in response to changes in climate. Our hypothesis for mapping freshwater resilience was that the physical setting and its intactness, together with water availability and its alteration, drive resilience in freshwater systems by providing habitat options and the conditions to maintain ecological function. We use the term “functional connectivity” to refer to the area of a river network available for a fish or aquatic organism to move through before they encounter a dam or other barrier. The characteristics of this “functionally connected network” - its size, diversity, condition, and available water – determine its ability to support aquatic diversity under changing climates. To assemble the Freshwater Resilient Connected Network (FRCN), we intersected the resilience analysis units (HUC12-FCN polygons) with areas of freshwater recognized biodiversity value to identify resilient areas with recognized biodiversity value and/or areas that were near resilient with recognized biodiversity value. The units that qualified for inclusion in the FRCN were placed into four primary groups representing key strategies: PROTECT Resilient. These are large, diverse, and connected river networks in good condition with ample unaltered water. The main conservation strategy for these systems is to protect their current state. RESTORE AND PROTECT. These river networks meet the resilience criteria in all but one primary category. Restore Condition. These are potentially resilient river networks in poor condition due to watershed fragmentation, degraded floodplain habitat, or poor water quality. The main conservation strategy is to restore the condition of these networks. Restore Flow. These are potentially resilient river networks with altered flow regimes due to the compound effects of upstream dams, water withdrawal, impervious surface, and/or groundwater depletion. The main conservation strategy is to restore flow—or ensure these river networks better simulate—natural flow regimes. In some cases, particularly in the agricultural Midwest, we accepted sites into this category if they were below average in both flow and condition as these factors are intertwined and because inclusion of these sites was necessary for adequate representation of Midwestern freshwater systems in the FRCN. Reconnect. These are potentially resilient river networks that are too small to provide many options to their resident species due to a dam or dams. The main conservation strategy is to remove the dam[s] or adjust dam operations in order to reconnect the river to its adjacent network. The above four classes can be further described by one of the 9 FRCN more detailed classes of which they are composed of. The specific criteria for each of the nine categories is described below. (note “RecBio” refers to recognized freshwater biodiversity) PROTECT GROUP: All units are Resilient scoring. 1. Protect: Highly Resilient (Resilient FAA-AA, with RecBio): ): Resilience Above Average (AA > 1 - 2 SD) or Far Above Average (FAA >2 SD) , and overlapping freshwater recognized biodiversity area 2. Protect: Highly Resilient (without recognized biodiversity) (Resilient FAA-AA, without RecBio): Resilience Above Average (AA > 1 - 2 SD) or Far Above Average (FAA >2 SD), without overlapping freshwater recognized biodiversity areas 3. Protect: Resilient (Resilient SAA, with RecBio): Resilience Slightly Above Average ( SAA > 0.5-1 SD) and overlapping freshwater recognized biodiversity area RESTORE GROUP: All units have recognized biodiversity value overlap and are "Average Resilience' scoring. These units are relatively close to resilient scoring and have enabling conditions that could likely allow them to move up into the resilient group with improvement in primarily a single factor that they are currently scoring below average in and that our restoration actions could address. 4. Restore: Condition (Restore Condition, with RecBio): Units meeting following criteria: In Humid Freshwater Ecoregions: Average Resilience, Condition Slightly Below Average or Below Average (but not Far Below Average), Size-Diversity and Water Alteration Average or better, and any Water Availability. In Arid Non-xeric Freshwater Ecoregions: Average Resilience, Condition Slightly Below Average or Below Average (but not Far Below Average), Size-Diversity and Water Alteration Average or better, and Water Availability Average or better. In Arid xeric Freshwater Ecoregions: Average Resilience, Condition Slightly Below Average or Below Average (but not Far Below Average), Size-Diversity and Water Alteration Average or better, and Water Availability Slightly Above Average or better. 5. Restore: River Flow and Condition (Restore Flow and Condition, with RecBio): Must contain > 0 km of river flowline (>100 sq.km drainage area) AND be of Average Resilience with Flow Alteration and Condition both Slightly Below Average or worse, Size-Diversity Average or better, and any Water Availability score. 6. Restore: River Flow (Restore Flow, with RecBio): Must contain > 0 km of river flowline (>100 sq.km drainage area) AND be of Average Resilience with Flow Alteration Slightly Below Average or worse, Size-Diversity and Condition Average or better, and any Water Availability score. 7. Restore: Reconnect (Reconnect, with RecBio): Because “Size” of the connected river habitat in this analysis is innately an FCN attribute, the criteria used for the “Reconnect” query included a set of FCN scale criteria to identify higher scoring FCN with certain enabling conditions, and then a finer spatial scale set of HUC12 criteria to identify the highly qualifying “seed” area or smaller HUC12s within qualifying FCNs. Only areas meeting BOTH the HUC12 and FCN criteria for enabling conditions are included. Additionally only "qualifying HUC12 areas also overlapping with Recognized biodiversity are included. The final full criteria for a HUC12FCN unit to qualify for inclusion in the "Reconnect" set of priorities included: FCN Size was Slightly Below Average or Below Average (not Far Below Average) and the FCN was bounded by dams and the current network was 60% or less of its natural size (e.g., removing a dam or multiple dams could restore it to a substantially larger length), AND the FCN resilience score (area weighted average of internal hucfcn units) was Average or better, AND HUC12 resilience score was Average (e.g. FCN and HUC12 units were both relatively close to resilient already -- so improving size alone could likely move the unit into resilience) AND the FCN (area weighted average of internal hucfcn units) and HUC12 Flow Alteration and Condition were Average or better, AND in arid ecoregions the FCN (area weighted average of internal hucfcn units) and HUC Water Availability was also “Average” or better. 8. Possible Addition: Verify Water (Possible Addition: Verify Water, with RecBio): This additional set of possible FRCN sites includes areas with recognized biodiversity that are the highest scoring in their ecoregion (>0.5) and have Average or higher key attributes, BUT appear to potentially be water limited because they score Average for Water Availability in an arid ecoregion. The detailed query includes those units in arid ecoregions that were Best in Ecoregion (either terrestrial or freshwater ecoregion), with Average Resilience, Average in Flow Alteration, Condition, Size Diversity, and Water Availability. These units were not previously added to the “Best in Ecoregion” override because they were too limited in Potential Water Availability. If water is verified in these areas, they are priorities to add to the FRCN. 9. Additional Area: Reconnect FCN (full FCN extent) (Possible Addition: Reconnect FCN (full FCN extent)). This category highlights all arcs within an FCN where there was a “seed hucfcn area” within that FCN that was highlighted for “Reconnect, with biodiversity.” This is a category to help visually see the extent of the whole FCN that would benefit from a dam removal. We limited this query to a set of FCNs that contained sufficient HUC12 areas within that qualified for “Reconnect with biodiversity.” Sufficient area was defined as > 10 sq.km of seed HUC12 “Reconnect with bio”, or >5% of the whole FCN area covered by the seed area. Arcs were also limited to those that didn’t qualify for any of the above eight previous queries.