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watershed news I ~. , After six years of drought and t\\'o decades of unprecedented growth in the already arid western Unites States, nothing defines this region more than its lack of water. And, the forecast isn't promising. The recently released Statewide \Vater Supply Initiative (S\VSI) report indicates that supply will fall 10 percent short of demand for Colorado in 2030 under the best circumstances. This may be the most appropriate definition of drought for water resource managers -- when water supplies cannot meet established demands. This is more than just a \vatcr quantity issue, however; drought also impacts water quality -- and watershed groups can playa vital role in mitigating these impacts. Drouaht 'mDacts on Water Qualify Stream Water The quality and quantity of natural flowing streams are directly impacted by the lack of rain and snowmelt. Contaminants already present may become concentrated and have a detrimental effcct on water uses. There is less good quality watcr available for drinking and stock water, crop and landscape irrigation. water-based recreation, aquifer recharge, and dilution water for waste\vater effiuent discharges. But the competition for this water docs not stop here. The water is still needed for maintaining water delivery to downstream users and for maintenance of healthy ecosystems. Healthy stream flows are necessary for stream channel maintenance and sediment flushing flows. habitat for aquatic wildlife. and natural ecosystem processes such as decomposition. \Vater quality impacts from drought in natural flowing streams include increased salinity. hardness. temperature, taste and odor problems. and microbial contamination. Excessive water use during periods of drought often dictates the artificial regulation and control of streamflow due to surface withdrawals. The new flow rates and volume rarely reproduce natural conditions \\-ithin streams and rivers. Criticalminimulll flows needed for riparian habitats downstream often are not maintained. Releases of impounded water (from reservoirs) generally have lower levels of dissolved oxygen. high turbidity. and altered temperatures \\-'hich can reduce downstream populations of fish and other aquatic wildlife. Lake and Reservoir Water Lower water levels in lakes and reservoirs can induce changes in temperature, dissolved oxygen. nutrient cycling. salinity. and seasonal water tUll1over. Exposed lake sediments in the larger beach areas nonnally under water ~an produce rooted plants that Watershed groups can playa critical role in the restoration of wetland and riparian areas that serve an important role in maintaining water quality. ~ " . .. - ~ .... then become submerged and die when the lake level returns. These dead and decaying plants release chemicals that, even at low levels, alter tastc and odor. Instream dams themselvcs create several forms of nonpoint source pollution that affect watcr quality both upstrcam and downstream. Degradation can include changes in temperature. dissolved oxygen, turbidity, and habitat. inundation of \vetlands and riparian areas. and impacts on aquatic life. The sediments. pesticides. petrochemicals. solid wastes. and other contaminants present on the landscape before the reservoir is built \vill be present in the reservoir water. The residence time can be long for these constituents in the water body. During drought, it may also be necessary to \vithdraw water from lower levels in reservoirs, which can lead to higher levels of trace clements in the water. Groundwater, Wells and Springs Under natural conditions, recharge and discharge of aquifers arc more balanced. Drought can alter these