Proponents of the concept of the hydraulic effect argue that the reduction or elimination of discretion in one area of the criminal justice system will simply resurface at processing stages that are not covered by the reform effort. This view was tested using data originally collected by the Minnesota Sentencing Guidelines Commission as part of their evaluation of felony sentencing practices. The sample included 1,273 felons convicted in Minnesota district courts for fiscal year 1978, 2 years before the State's sentencing guidelines went into effect; 1,369 felons from the first 18 months under the guidelines; and 1,738 felons processed during the subsequent 12-month period, from October 1981 to September 1982. The analysis considered charging and two types of plea bargaining -- charge bargaining and sentence bargaining -- as the dependent variables. The independent variables were the offense, case processing, and offender attributes expected to influence results of plea bargaining. The main case processing variable was the county of adjudication. Time-specific models for initial charging practices and each type of plea bargaining were estimated to examine whether the determinants of these dispositional decisions had changed over time. Findings did not support the concept of the hydraulic effect. The Minnesota guidelines appear to be a successful experiment in criminal justice reform. 40 footnotes.