HYDROLOGY

The streams in South Latourette Park are tributaries of the Fresh Kills, which drains into the Arthur Kill stream channel. Within the study area, all drainage enters Richmond Creek, which flows westerly until it joins the Fresh Kills. An unnamed tributary drains southwestward in the northern part of the study area (Fig. 2). This creek was diverted in the 1820s from the millpond south over the drainage divide to the upland grist mill. After the mill was closed, the creek flowed southwest again into the marsh until the lower reaches were blocked by the landfill construction. The lower reaches now join the Richmond Creek Estuary just east of the West Shore Expressway.

Richmond Creek is an estuary, the water level having a normal tidal range of about five feet (USGS data). Extensive tidal marshes once lined its banks, and many of these areas were ditched to increase their rate of drainage. A significant proportion of these wetlands are now occupied by municipal solid waste landfills where the Greatkills soil now exist.

GROUNDWATER AND AQUIFER RECHARGE

After rainwater infiltrates the soil, it flows downward through pores and cracks until it reaches the depth below which the soil is saturated with water. The surface of this saturated zone is called the water table. The water table usually is not level but has some slope, which allows groundwater movement to occur.

Saturated soil materials, such as gravel, sand, or fractured bedrock called aquifers, contain large pores to allow water to flow through them readily. Within aquifers, groundwater behaves somewhat differently than surface waters, such as streams or lakes. While surface waters flow downhill under the influence of gravity, groundwater flows toward areas having lower hydraulic pressure (i.e. lower "head"). Areas having higher head tend to be at relatively high elevations in the landscape, such as ridgetops. This location is where groundwater is recharged, especially if the soil is sandy or gravelly, such as the Penwood and Manchester soils. Areas with lower head tend to occur at lower land elevations, such as concave areas, valleys or near estuaries, and are often groundwater discharge zones. Fredon, Wallkill and Rippowam soils occur in these areas. Groundwater commonly flows upward in these discharge zones, being forced against the pull of gravity by water higher in the aquifer that has greater hydraulic head. Soil interpretations listed in the Soil Map Unit Description section can be applied by computer programs to identify areas of turfgrass with severe hazards of groundwater contamination from excess herbicide, pesticide, and fertilizer use (Fig. 10).

Figure 10. Soils of the golf course area with turfgrass cover that have: severe risk for pesticide leaching losses to groundwater or aquifers because of a shallow water table (Lw) or because of high potential for groundwater recharge (Lg); or have severe risk for pesticide losses in runoff because of steep slope and high runoff (R).