Using a combination of tabular and spatial data queries, we identified 129,773 flowlines in the hydrological framework of the National Hydrography Dataset Plus Version 1 (NHDPlusV1) that were created due to breaks in flowlines resulting from flowline intersection with quadrangle map boundaries. We found instances of this occurring in all 18 processing units of the NHDPlusV1 dataset. To aid in managing for this characteristic of the NHDPlus, we developed this EcoReach table (nhdplusv1_ecoreachv2.0.csv) that assigns all flowlines into units that are representative of ecological stream reaches. These "ecological stream reaches" may be defined by: stream origins, stream confluences, lake or reservoir inflows or outflows,...