June 30, 2014. Last week, the House approved a new version of House Bill 1057 (originally a study of interbasin transfer issues). The House added a new section requiring the Environmental Management Commission (EMC) to study the method used for establishing minimum stream flows necessary to protect stream ecology — or “ecological flows”. In the meantime, the bill would prevent the Department of Environment and Natural Resources (DENR) from developing river basin hydrologic models based on the recommendations of an ecological flow study just completed in late 2013 — work the General Assembly itself directed in 2010 legislation.
The state’s Division of Water Resources (DWR) has been working on river basin hydrologic models for more than a decade. The models turn information like water volume; seasonal flow; user demand (such as drinking water intakes); and permitted wastewater discharges into a tool for predicting how water supply will respond to different conditions. Federal relicensing of North Carolina’s hydropower dams prompted development of some of the earliest hydrologic models; those models became the basis for new hydropower license conditions. DWR has completed models for most of the state’s major river basins; the piece missing from the models has been a placeholder for water needed to maintain aquatic ecosystems.
State and federal permit reviews for large water supply projects (like reservoirs and new drinking water intakes) have long required analysis of impacts on aquatic life as well as downstream water users. The analysis has generally been done by the permit applicant on a project by project basis. Session Law 2010-143 required DENR to characterize the ecology of the state’s river basins; identify the flow needed to maintain the integrity of those ecosystems; and incorporate the “ecological flow” into each river basin hydrologic model. S.L. 2010-143 did not give the “ecological flow” component any regulatory effect; the law simply set in motion a process for looking more systematically at the impact of stream flows on aquatic ecosystems. Even though the law had no immediate regulatory impact, it immediately encountered opposition from some municipalities — led by the City of Raleigh — out of concern that development of ecological flows would lead to greater limits on public water supply projects.
As required under S.L. 2010-143, DENR convened a science advisory board to recommend a method for identifying the minimum stream flow necessary to maintain ecosystem integrity in each of the state’s river basins. The science advisory board included representatives of agriculture, local government, electric utilities, conservation organizations and both state and federal regulatory agencies. The advisory board’s 2013 report titled “Recommendations for Estimating Flows to Maintain Ecological Integrity in Streams and Rivers in North Carolina” just became available in November 2013. The report recommends a minimum “flow-by” (the percentage of flow that remains in a stream after allowing for withdrawals ) of 80-90%. Based on the recommendation, DENR intends to use 85% flow-by as a planning tool, but will not change existing permitted flows or individually determined flow regimes. DENR has also indicated that more data will be needed before implementing other recommendations in the report. You can find a DWR presentation on use of the science advisory board’s report here .
House Bill 1057 appears to reject outright the work done by the science advisory board and requires the EMC to do a new review of methods used to establish ecological flows — again based on the provisions of S.L. 2010-143. The bill also allows the EMC to create another scientific advisory panel. It isn’t clear what would be accomplished other than a further delay in consideration of ecological needs in river basin wear supply modeling.
In some ways, the ecological flows controversy parallels the earlier (successful) effort to limit use of sea level rise projections in state planning. Opposition to possible policy changes no longer waits for the actual policy discussion — instead, the opposition has organized to limit use of the underlying scientific or technical information.