Abstract: A multi-parameter tool assembly provides for monitoring of one or more parameters, such as those relating to water quality. As part of the tool assembly, a sensor head is configured to receive and electrically interconnected with a plurality of interchangeable sensor head components. The sensor head components are specially configured to provide for the removal and insertion out of sensors through the application of a linear force. The housing for the tool assembly, which may include a plurality of layers, is further configured for simplified assembly with the sensor head and other components through the use of at least one radially compressive sealing device. The assembly is further connectable to a communications network wherein signals may be exchanged with one or more remote locations.