This paper addresses support for energy efficient singlehop communications in Environmental Monitoring Wireless Sensor Networks (WSN). The main contributions are twofold firstly; the identification of scenarios where single hop communication, between multiple sensors and a base station is both feasible and offers benefits with respect to power preservation. Secondly, the design implementation and evaluation of the Power and Reliability Aware Protocol (PoRAP) which can minimize energy consumption whilst preserving reliability is presented. PoRAP is a measurement based adaptive protocol that provides probabilistic reliability. It uses measurements of Received Signal Strength Indicator (RSSI) to identify when the transmission power can be decreased without reducing the Packet Reception Rate (PRR). Consequently, reduced power can often be used for transmission. In PoRAP source transmission is scheduled and radios only start for the reception of control packets and data transmissions. The scheduling reduces the likely hood of collisions and minimizes idle listening. The required duty cycle is reduced further by tracking clock drift between sensors and base stations. In these ways PoRAP reduces the power required forsingle hop communication between a sensor and its base station.