Chapter IV - Affected Environment, cont.

The Natural Environment

Regional Geology

Whitman Mission NHS is located in the Walla Walla Basin. The bedrock of the Walla Walla Basin is composed of layered flows of Columbia River Basalt of the Miocene and Pliocene ages and is over 3,000 feet thick. These layers are often separated by sedimentary beds of clay, diatomite, tuff, pumicite, or sand. The uppermost layer of basalt at Whitman Mission National Historic Site is approximately 524 feet below the surface. Above this are continental deposits of clay and gravel, probably of Pleistocene age. Overlying the old gravel is a mantle of Pleistocene silty and clayey loess known as the Palouse Formation. This constitutes the predominant parent material for the soils of the area.

Climate

The climate at Whitman Mission National Historic Site is dry and moderate. Annual precipitation in the vicinity of the NHS averages 15.98 inches of rainfall (determined from a 7 year average), including the melted water content of snow. Approximately 17.8 inches of snow falls during the winter months. The daily temperature variation can be as much as 40 degrees during the summer. Mean monthly maximum temperatures range from 40.1 to 97.3 degrees Fahrenheit, while mean minimum temperatures range from 26.6 to 57.4 degrees Fahrenheit. Frequent, strong winds can occur anytime, as well as chinook winds. Prevailing winds year around come from the southwest.

Weather Station
On the northern edge of the maintenance facility area is a fenced space approximately 15 feet by 15 feet that is used for weather monitoring. The National Weather Service furnished and presently maintains the equipment. Whitman Mission National Historic Site staff make observations each day and provide the National Weather Service staff with the data. This weather observation station is designated as the official precipitation monitoring station for Walla Walla, Washington. The NHS staff is responsible for furnishing daily maximum and minimum temperatures, precipitation, and water evaporation data to agencies and organizations that request it, as well as to the National Weather Service. Evaporation and wind speed also are recorded during the growing season, which is approximately April through September. Whitman Mission National Historic Site has been a National Weather Service cooperative weather observer since 1936.

Air Quality

Whitman Mission has been designated a Class II 2 area for purposes of controlling increases in air pollution under the Clean Air Act. No air quality monitoring presently is conducted at the NHS or in surrounding areas. The closest air quality monitoring station is at La Grande, Oregon, 70 miles southeast of the NHS. Other stations are located in North Cascades National Park and Mount Rainier National Park in Washington. The Washington State Department of Ecology has an air quality office in Kennewick and another in Spokane. One of the primary concerns of the office is wind blown dust produced from agricultural operations. The Walla Walla County Burn Control Office now operates a phone line which relays information concerning burning.

Air quality is important to Whitman Mission National Historic Site in terms of visibility. Generally, wind conditions maintain clear visibility in the area. Notable exceptions to clear visibility occur in the spring and fall during agricultural operations. Thick dust is blown from the plowing and planting of adjacent agricultural fields, and smoke occurs during the burning of agricultural fields. During periods of atmospheric inversions, smoke and dust can become trapped over the Walla Walla Valley.

Soils

Digital soil maps for Whitman Mission National Historic Site do not exist. Soil maps for Walla Walla County were published in 1964, by the USDA Soil Conservation Service (now the Natural Resources Conservation Service). At a scale of 1:31,680, or one inch equaling one-half mile, the 98.15 acre NHS is covered in less than two square inches on the map. Soil information on file at the NHS was hand-drawn onto an aerial photograph of the NHS taken about 30 years ago.

Generally, the soils at Whitman Mission vary and include gravel, organic soil, silt loam, loess, hard pan, and clay. The water table ranges from one to four feet deep through most of the lower elevations of the NHS. Frost penetration averages eight inches with a maximum of sixteen inches.

Topography

Whitman Mission National Historic Site is located at the southern extreme of the Palouse Prairie region of southeastern Washington. The township and range reference is Township 7 North, Range 35 East, Section 32, of the United States Geologic Survey (USGS) Topographic Quadrangle Map, College Place 1966. General elevation within Whitman Mission National Historic Site is level and ranges from 615 feet above sea level to 724 feet at the top of Memorial Hill (which rises over 100 feet above the surrounding countryside).

Water Resources

Surface Hydrology
Surface water resources at the NHS 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, a former dairy, and agricultural land before entering the NHS at the northeastern boundary. Here, Doan Creek splits into two channels through the NHS; 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 Swegle Road near the intersection with Whitman Mission Road (the NHS's entrance road). Further west, Mill Creek joins the Walla Walla River.

The historic Millpond covers about two and one-half acres and is held by earthen dikes. The Millpond was restored in 1961, and is located on the eastern end of the Mission Grounds. The Millpond is supplied by the irrigation channel from Doan Creek.

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. Currently, Whitman Mission National Historic Site is responsible for maintaining 5,967 feet of irrigation ditch in accordance with Washington State law. The current irrigation ditch on the NHS land supports water that supplies two farms west of the NHS.

There have been previous discussions as to which portion of Doan Creek is an irrigation ditch and which portion is classified a creek under the state hydrological permitting process. The concern raises issues as to the appropriate maintenance of the channel to allow for water flow. If the channel is an irrigation ditch then no permits are necessary from the state for ditch maintenance undertaken by the NHS staff. If the channel is classified as a creek, then permits are necessary for maintaining water flow. Presently, the state views the irrigation ditch as Doan Creek. During a 1997 meeting with the Water Master (Washington State Department of Ecology) and the Washington State Department of Fish and Wildlife, it was decided to place a screen at the diversion box where Doan Creek enters the NHS. This screen would prevent fish from entering the irrigation channel thereby keeping that channel an irrigation ditch. A permit is then not necessary for maintaining water flow. Doan Creek has been manipulated to the point that the natural channel is not readily distinguishable. At least portions of the original stream bed could be reestablished by use of old maps. This would allow for the establishment of a free-flowing Doan Creek and a defined irrigation ditch.

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 NHS. 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.

Restoration of Doan Creek

Doan Creek before restoration

In 1995, the staff at Whitman Mission NHS contracted with Inter-Fluve, Inc. located in Hood River, Oregon, to prepare a restoration plan for Doan Creek. Historically used for irrigation, Doan Creek had been changed so that the natural historic stream alignment was unclear. The intent of the study was to restore in part the natural stream system function of the north channel, and to allow irrigation to continue through the NHS. The primary goal of restoring Doan Creek was to reduce annual channel maintenance. The suggested restoration techniques, which are now being implemented, would restore partial functionality by preserving or modifying vegetation and physically modifying some of the channel segments. In general, the northern channel would be restored to a natural meandering stream (closer to its original condition) with wetlands. Native hardwood trees and shrubs would be planted to provide shade and long term stability, and to increase the potential for wildlife. Since the southern channels have significant cultural resources, this area would be maintained as an irrigation-type channel. The banks of the irrigation ditch would be stabilized through the Mission Grounds and the remainder of the irrigation channel would be assessed for other management options.

Subsurface Hydrology
The park's potable water well draws water from a gravel aquifer, the shallower of the two aquifers underlying the Walla Walla Valley. The well is certified by the Washington State Department of Ecology. During the 1970s, Whitman Mission participated with local government agencies and landowners to monitor the depth of water in the shallow aquifer. The Walla Walla Regional Water Study Committee was the umbrella organization that compiled the data. The study confirmed that, in general, the water level in this aquifer is becoming deeper.

Whitman Mission will not experience a shortage of water in the foreseeable future because the park well goes into the aquifer for a considerable depth. Most county residents depend upon the aquifer and the cities of Walla Walla and College Place use the aquifer when demand is highest in the summer. Walla Walla and the Washington State Department of Ecology have proposed a program to pump water from the deep basalt aquifer into the shallow aquifer to stop the loss of water from the shallow aquifer. Whitman Mission would cooperate again with any regional organization to monitor water depth in the park well.

Water Quality
The chemical analysis of the potable well water has been consistently monitored every three years. In 1992, the national historic site received funding to test the surface waters of Doan Creek and the Millpond for 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. The NHS staff received funding for subsequent water quality monitoring in 1998, and again, no pesticide pollution was detected.

The National Park Service's Water Resources Division in Fort Collins, Colorado, reviewed six national databases maintained by the U.S. Environmental Protection Agency for water quality monitoring data within the area of the NHS. Of the 8,307 monitoring observations reported in the databases, approximately 95% were recorded before 1978. Samples were not collected from 1978 through 1991. The only recent water quality monitoring is mentioned above. From the limited available data, it appears sections of the Walla Walla River, Mill Creek, and the Millpond have been influenced by human activities. Potential human sources of contaminants include upstream, historic wastewater discharges, or both, along with mining and quarrying operations, agricultural runoff, and urban storm water runoff.

Water Rights
At the time of land acquisition for Whitman Mission National Historic Site, certain water rights also accompanied the acquired properties. The NHS obtains its water rights certificates through the Water Rights Program administered by the Washington State Department of Ecology. The NHS holds water rights certificates including ground wells and from surface waters. Future use of these water rights and resources is an obvious management concern at the NHS, while continuing to respect the valid existing water rights of downstream users.

Irrigation water from Doan Creek is shared among three land owners-the NHS and two neighbors. Maintenance of a free-flowing irrigation channel is accomplished cooperatively among the three interests for the portion of the irrigation ditch east of the NHS. The NHS staff is responsible for the maintenance of the irrigation ditch within the park. A fourth party, over whose land the upper part of Doan Creek runs, but who has no water rights, is also involved. The National Historic Site is situated between this neighbor and the other two; therefore, the NHS is the first to be called upon to correct any problem concerning irrigation water flow, such as water leaks, and weed and moss control. The NHS uses its share of water to fill the historic Millpond and irrigate 10 acres of lawn at the Mission Grounds. The other two neighbors with water rights irrigate their respective farms. To assure the other users that the NHS was using no more than its fair share of water, the staff installed a meter in 1996 to measure the amount of water used for irrigation.

Wetlands
Approximately 10 acres of the NHS is wetland, but is not formally classified as such in any NPS, U.S. Army Corps of Engineers, National Wetlands Inventory, or Natural Resource Conservation Service document. The NHS staff needs to have this area formally evaluated. There are distinct former stream channels of Doan Creek and the Walla Walla River which hold water in the winter and spring. There is a wetland enhancement project planned by NHS staff to unchannel Doan Creek along the northern boundary to allow more water to meander, supporting the wetland habitat mentioned above.

The U.S. Army Corps of Engineers purchased land that borders the south boundary of the NHS and the north bank of the Walla Walla River as part of the Snake River Mitigation Plan. This land is now owned and managed by the Washington State Department of Fish and Wildlife as a riparian habitat. Management of this land in its natural state is compatible with the historic setting of the NHS.

Floodplains
The Floodway, Flood Boundary and Floodway Maps published by the Federal Emergency Management Agency (Panel 440 of 500, December 1, 1983, Walla Walla County, Washington, Unincorporated Areas) show Whitman Mission National Historic Site to have approximately 50% of its land area in either the 100 or 500-year flood boundary of the Walla Walla River or Mill Creek. (Refer to Figure 2, Physical and Natural Features.) The northern portion of the NHS is situated in the Lower Mill Creek floodplain, with the 100-year flood boundary at an elevation of about 623 feet, while the 500-year flood boundary is at approximately 626 feet. No NHS facilities are located within this floodplain, although the maintenance area is close to the boundary.

In the southern portion of the NHS, the Walla Walla River floodplain, has the greater extent of potential flooding. The 100-year flood boundary is at an elevation of approximately 618 to 621 feet, and extends from an east-west line that runs just south of the Millpond. The 500-year flood boundary would cover the entire Mission Grounds and the Oregon National Historic Trail. However, no NPS buildings would be affected. The concrete walkway, and a portion of the NHS road at the entrance to the NHS would be the only NHS improvements to be affected.

Walla Walla County ordinances prohibit development in the floodway and impose limitations and building in the 100-year floodplain.

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2. The 1977 Clean Air Act amendments designated all national parks over 6000 acres and wilderness areas over 5,000 acres as Class I. This classification affords the most protection from new major emitting sources. All other areas that meet the National Ambient Air Quality Standards were designated Class II.
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