Designated in 1991, CBNERRVA established a multi-component system along the salinity gradient of the York River estuary that encompassed the diverse collection of habitats found within the southern Chesapeake Bay subregion. With its two principal tributaries, the Pamunkey and Mattaponi Rivers, the York River is the Bay's fifth largest tributary in terms of flow and watershed area. The York River estuary is classified as a microtidal, partially mixed estuary. Tidal range varies from 0.7 m and at its mouth to over 1 m in the upper freshwater tributary reaches and salinity distribution ranges from tidal freshwater to polyhaline regimes. Land use is predominantly rural in nature with forest (61%) and agricultural lands (21%) being the dominant land cover; wetlands comprise approximately 7% of the basins area. Reserve components include: (1) Goodwin Islands (148 ha), an archipelago of polyhaline salt-marsh islands surrounded by inter-tidal flats, extensive submerged aquatic vegetation beds, and shallow open estuarine waters near mouth of the York River; (2) Catlett Islands (220 ha), consisting of multiple parallel ridges of forested wetland hammocks, maritime-forest uplands, and emergent mesohaline salt marshes; (3) Taskinas Creek (433 ha), containing non-tidal feeder streams that drain oak-hickory forests, maple-gum-ash swamps and freshwater marshes which transition into tidal oligo and mesohaline salt marshes; and (4) Sweet Hall Marsh (443 ha), an extensive tidal freshwater-oligohaline marsh ecosystem located in the Pamunkey River, one of two major tributaries of the York River. CBNERRVA manages these reserves to support informed management of coastal resources by supporting research that advances the scientific understanding of watershed and estuarine systems, highlighting proper stewardship of coastal resources, and improving general public and professional literacy through education and training programs.