Initial release.

This release is an initial offering of reference dams based on a recent snapshot of the National Inventory of Dams and

Wieczorek, M.E., Wolock, D.M., and McCarthy, P.M., 2021, Dam impact/disturbance metrics for the conterminous United States, 1800 to 2018: U.S. Geological Survey data release, https://doi.org/10.5066/P92S9ZX6.

Network locations of dams have been established using some initial network location logic using drainage area as an indication of network matches.

There is a new "index_type" attribute which describes how the network location was determined.

"automatic" means that a network snap was used to determine the flowline the dam is along.

For dams with drainage area estimates from the National Inventory of Dams or the 2021 data release referenced above, drainage area was used as a matching criteria.

For the 2021 data release source, three categories were established:

• <10sqkm_da_mismatch is for dams near a headwater such that a drainage area mismatch is tolerable because NHDPlusV2 drainage area is at the outlet of a whole catchment.
• off_network_da_mismatch is where the dam's drainage area is very different from the catchment the dam is in so the dam is assumed to be off the flowline of a catchment.
• on_network_da_match is where a dam's drainage area is similar to that of the NHDPlus and is assumed to be on network.

The following is counts of each category included in this release.

      automatic_network_closest_drainage_area
                                         10100 
automatic_network_closest_flowline_no_da_check 
                                         12863 
                     nawqa_<10sqkm_da_mismatch 
                                         14155 
                 nawqa_off_network_da_mismatch 
                                          8356 
                     nawqa_on_network_da_match 
                                         27324