2019_KittitasCountyHMP_Volume 1_For Adoption

Home Browse Search

CHAPTER 4. KITTITAS COUNTY PROFILE 4-6 than the ability of soil microorganisms to purify it, thus increasing the chance of groundwater contamination. Proper precautions should be taken when developing areas considered to have aquifer recharge potential so that the function of these areas may be maintained without depleting or contaminating groundwater supplies. The ability of soils to allow replenishment of groundwater reservoirs becomes an increasingly important consideration as more demand is placed on groundwater for commercial and domestic use. Large areas of high aquifer recharge potential are found in the Yakima River Basin and its tributaries within Kittitas County. However, no critical aquifer recharge locations have been identified in Kittitas County, according to the Interim Critical Areas Development Ordinance 94-22. Agricultural Suitability The suitability of soils for agricultural production has been classified by the USDA NRCS Soil Conservation Service into eight classes. These categories are determined by expected crop yields and required soil management techniques. Generally speaking, Class 1 through Class 4 soils produce the highest yields with the least amount of soil management. Class 5 through Class 8 soils require more costly soil management and lower yields are expected. Kittitas County contains a considerable diversity of soils with varying agricultural properties for growing crops and trees. 4.3.4 Seismic Features Seismic events could pose limited landslide and liquefaction hazards in areas where steep or exposed slopes occur. Landslides occur when the structural integrity of a geological formation is damaged. There are known areas of landslide activity, which may or may not have resulted from seismic events, along the Yakima River. Soil liquefaction occurs when soil loses its strength and bearing capacity during an earthquake. This is most likely to occur on non-cohesive soils with high moisture content. These soils are poorly compacted and, in combination with moist conditions, are subject to liquefying during an earthquake. Structures built on liquefiable soils are subject to greater shaking and damage during an earthquake, but this damage can be minimized by engineering and construction methods. Kittitas County has little potential for seismic events other than secondary effects from activity occurring west of the Cascades. The Uniform Building Code rates seismic risk from 1 (low risk) to 4 (high risk). Most of Kittitas County is within Seismic Zone 2. The Snoqualmie Pass area is within Zone 3. 4.3.5 Climate Eastern Washington climate is a function of maritime and continental influences. The Yakima River basin’s location just east of the Cascade crest places it in a rain shadow, with hotter summers, colder winters, a shorter growing season, and less precipitation than areas of similar latitude west of the Cascades. Temperatures generally increase and precipitation generally decreases from northwest to southeast and from high to low elevation. Temperatures Because of the variation in elevation, temperatures vary greatly in the Yakima River basin. In the Kittitas Valley, summers tend to be hot, with wide divergent fluctuations, and mild to severe winters. Data is scarce for higher elevations; however, those areas are generally characterized by cool summers and cold winters. For example, in the Subalpine Fir forest zone, which extends from approximately 2,000 feet to the timberline, mean July temperatures in the range of 55ºF to 65ºF can be expected.