Which of the following measures indicates the rate at which clear water seeps out of a test hole?

The measure that indicates the rate at which clear water seeps out of a test hole is best identified as hydraulic conductivity. Hydraulic conductivity is a specific measurement that quantifies how easily water can flow through soil and is typically expressed in units such as centimeters per second. This property reflects the ability of the soil to transmit water under saturated conditions, which is essential for understanding groundwater flow, drainage, and the effectiveness of septic systems.

While soil permeability and soil percolation tests are related concepts, they do not directly measure the seepage rate from a test hole in the way hydraulic conductivity does. Soil permeability refers to the capacity of the soil to allow fluids to pass through it, which can vary based on factors like soil texture and structure. Soil percolation tests are specifically designed to assess the rate at which water moves through soil by measuring the drop in water level in a test hole over time but do not provide a specific measure of hydraulic conductivity.

The Baird-Parker saturation test, primarily used in microbiological contexts, is unrelated to the measurement of water infiltration rates in soil. Therefore, hydraulic conductivity is the most accurate term for describing the rate at which clear water seeps out of a test hole.