Jackson Bottom Wetlands Preserve
Water Quality Monitoring Sites
Jackson Bottom Wetlands Preserve — southern end of Preserve
Tualatin River Monitoring Site
The Tualatin River drains an area of 712 square miles. The river generally flows in easterly direction from its headwaters in the Coast Range to its confluence with the Willamette River. The river is approximately 83 miles long, with several tributaries, including Scoggins, Gales, Dairy, Rock and Fanno Creeks.
Jackson Bottom Wetlands Preserve is located in the 3000-acre Jackson Bottom floodplain of the Tualatin River. Jackson Bottom is located just downriver of the Dairy Creek confluence with the Tualatin. In winter and spring, as a result of significant precipitation events, the Tualatin River overflows onto large areas of the Preserve. Most of the Preserve is at 128-130 feet MSL (above Mean Sea Level). The water quality monitoring site at the Preserve is at River Mile (RM) 44.4. (RM 0 is at the confluence with the Willamette River.)
Gene Pool Monitoring Site
The “Gene Pool” is a restored wetland pond on the Jackson Bottom floodplain. It is named after Gene Herb, a retired wildlife biologist, who serves on the Preserve’s Board of Directors. The Gene Pool is located about 1/4 mile northeast of the Education Center. The Gene Pool was constructed in 1998 to provide open water habitat for ducks and other water birds. A water quality station is maintained at the Gene Pool. In order to interpret the water quality data, a basic understanding of the hydrology of the Gene Pool is needed.
For much of the year the Gene Pool is hydraulically separated from the rest of the floodplain. A low berm holds water in the Gene Pool. Groundwater flow is generally low due to the low permeability of the silt and clay soils. During the summer, much of the Gene Pool dries out, exposing mudflats that are used by shorebirds. The west portion of the Gene Pool, where the water quality monitoring station is located, generally still holds water during the drier months. During the summer there is considerable growth of aquatic plants and algae.
Clean Water Services recycles treated wastewater in the Gene Pool in late spring (May - June) and again in fall (November - December). The treated wastewater is discharged into the east side of the Gene Pool; the monitoring site is on the west (opposite) side. In winter and spring, as a result of significant precipitation events, the Tualatin River overflows onto large areas of the Preserve, including the Gene Pool. At water levels above approximately 129 feet above Mean Sea Level (MSL) , water flows into the Gene Pool.