Sweet Hall Marsh is the lower-most extensive tidal fresh water marsh located in the Pamunkey River, one of two major tributaries of the York River. The reserve is 353 ha (871 acres) in area and includes 331 ha (818 acres) of emergent fresh-water marsh, 14 ha (35 acres) of permanently flooded broad-leaved forested wetlands and approximately 4 ha (9 acres) of scrub-shrub. The marsh community is classified as freshwater mixed. Vegetation in the creekbank zone of Sweet Hall Marsh includes arrow arum, smooth cordgrass, big cordgrass, smartweeds, rice cutgrass, wild rice, water hemp, water dock, Walter's millet and marsh milkweed. Sedges (Carex spp.), reed grass, rushes (Scirpus spp.), cattail, marsh mallow and panic grass can be found in the levee zone of the marsh along with species found along the creekbank. The low marsh interior is dominated by arrow arum. The sensitive jointvetch (Aeschenomene virginica), a candidate for federal listing as an endangered species, is found in Sweet Hall Marsh. Mean tidal range at Sweet Hall Marsh is on the order of 0.9 m.

Location and Access:

Sweet Hall Marsh (37° 34' N; 76° 50' W) is approximately 7 km from West Point, where the Pamunkey and Mattaponi converge to form the York River. The site is 63 km upriver from VIMS and 83 km from the mouth of the York River. This reserve site is privately owned and permission must be obtained prior to any use. Please contact Reserve staff for more information.

Monitoring Programs:

Water Quality Monitoring - An Endeco YSI Environmental Monitoring System PC6000 or PC6600 is deployed in a permanent station built 3 meters from the bank in the Pamunkey River. The station is adjacent to Sweet Hall Marsh on the downriver side. Water temperature, water depth, pH, dissolved oxygen, salinity and turbidity have been recorded since January 1999. Beginning in 2002, water column inorganic nutrients (ammonium, nitrate, nitrite, ortho-phosphate), total dissolved nitrogen and phosphorus, and chlorophyll are measured monthly at the water quality monitoring station.

Biological Monitoring - Many research projects investigating the freshwater marsh plant community and nekton utilization of the marsh, intertidal zone and subtidal waters around Sweet Hall marsh have been conducted. Please contact Reserve staff for more information regarding this or any other CBNERRVA monitoring program.

Meteorological Monitoring - A Campbell Scientific UT-10 meteorological station records wind speed and direction, air temperature, relative humidity, rainfall, barometric pressure and photosynthetic active radiation (PAR). The weather station is located in an agricultural field immediately adjacent to the marsh. The weather station was established in March 1998 and is currently operational.