sentences:  At in size, it is larger than all four mainstem Klamath reservoirs combined (excluding Upper Klamath Lake).According to the USGS watershed classification system, the Klamath Watershed is a 6-digit, level 3 Accounting Unit within Region 18, known as the California watershed region.The accounting unit of the Klamath Watershed is 180102 and includes twelve 8-digit Hydrologic Units (HUCs) covering 9.4 million acres.