Hydropower and instream flow requirements for fish in Sweden

Abstract

SwedPower AB, Stockholm, SwedenStandardized methods for determining instream flow needs in connection with hydropower development have still not been established in Sweden. However, claims related to conflicting uses of running waters have long engaged the Water Right Courts. Historically, the floating of timber has constituted a strong reason for regulating rivers. Later, the creation of large reservoirs and the subsequent alteration of the natural river flow have mainly been related to the generation of hydroelectricity. In recent decades, the expectations of stakeholders have also been directed at recreational fisheries and the maintenance of biodiversity. Dry channels below diversion points are no longer considered acceptable. Swedish legislation allows for a regular review and reissue of permits to regulate rivers and operate hydroelectric power plants. However, it is only possible to enforce changes which are economically reasonable. The maximum loss of electricity which must be endured by a producer without reciprocal demands of compensation amounts to 5%. Presently, fishing may be regarded as the second most important interest in terms of the use of river resources. Accumulated knowledge of fish ecology makes it possible to use models for the management of fish populations. However, decisions regarding minimum releases of water are usually still based on the natural hydrograph rather than on documented relationships between fish yield and the characteristics of the watercourse. Over the past 7 years, Vattenfall, the largest producer of hydroelectricity in Sweden, has carried out research and development to test, improve and introduce instream flow methods for the management of regulated rivers. Experiences regarding biotope adjustments as an alternative to increased releases of water are presented, and the economic and biodiversity aspects are discussed.