Eastern Washington
Eastern Washington: Septic on the Dry Side of the Cascades Eastern Washington. Cross the Cascade Range heading east and Washington’s septic story changes entirely. Spokane and the surrounding region sit in a rain shadow — the mountains block most of the moisture rolling in off the Pacific, leaving Eastern Washington with a climate closer to the arid interior West than to the famously wet lowlands just 200 miles away. Same state code, different soil story: Eastern Washington systems still fall…