Alterra Power Corp. has a deal to buy the water rights for four hydroelectric projects along British Columbia's Toba Valley. The projects are 20 to 30 kilometres from the Toba Montrose and Jimmie Creek hydroelectric operation that Vancouver-based Alterra is developing about 80 kilometres from Powell River, B.C. Alterra said it's buying the water rights from Sigma Engineering, a subsidiary of Synex International .