Whitman Mission National Historic Site - Water Quality

Surface water resources at the park include Mill Creek, Doan Creek, the Millpond, and the irrigation ditch. Mill Creek originates in the Blue Mountains, approximately 30 miles east of Whitman Mission and flows through the northwestern corner of the NHS. Doan Creek originates three miles east of the NHS and passes through a private airport and agricultural land before entering the NHS at the northeastern boundary. Here, Doan Creek splits into two channels; one continuing west along the northern boundary until joining with Mill Creek (this is the historic channel); and the other irrigation channel turning south, then west and connecting back to Mill Creek just west of the park’s entrance road. The historic Millpond covers about two and one-half acres and is held by earthen dikes. The irrigation channel from Doan Creek supplies the Millpond. Marcus Whitman is credited with establishing the first irrigation ditch in this area. In one form or another at least one irrigation ditch has crossed the Mission Grounds since Whitman’s time. In addition to the existing surface water resources, evidence exists of former stream channels for both Doan Creek and the Walla Walla River. A former Doan Creek channel is an important wetland habitat in the northeastern quarter of the park. The former channel of the Walla Walla River (the oxbow of the Walla Walla River) is important to the interpretation of the history of Whitman Mission National Historic Site. The park’s potable water well draws water from a gravel aquifer, the shallower of the two aquifers underlying the Walla Walla Valley. The surface waters of Doan Creek and the Millpond are periodically tested for their basic water chemistry such as pH, temperature, nitrate, dissolved oxygen, and other factors. Water quality is good, although pH and temperature levels are higher than optimum for native fish habitat. Doan Creek was also tested for potential pesticide pollution. No pesticides were detected.