Major challenges are projected for crops that are near the warm end of their suitable range or depend on highly utilized water resources . Human health Adverse health impacts from climate change have already been documented, and are expected to increase during the twenty-first century. Montanans will experience health impacts from increased temperatures and decreased stream flows that are similar to those in other parts of the country. Decreased summer stream flows will lead to heavier concentrations of pollutants including toxic metals, microbes and nutrients. Higher temperatures and increased forest fires will adversely affect air quality, increasing incidences of asthma, lung and heart disease. On average, climate change has already extended the allergy season by 20 days annually since 1950. State adaptation and mitigation Renewables In April, 2005, Montana established a renewable energy portfolio which requires all public utilities to derive at least 15% of their electricity from renewable energy resources by 2015. Part of Montana's renewable energy development plan is to stimulate rural economic development by requiring public utilities to buy renewable energy credits and electricity generated by community-based energy utility companies. From 2010 to 2014, public utility companies in Montana must purchase 50 MW from these rural community-based utility companies. Beginning in 2015, that figure will grow to 75 MW. Any utility company serving more than 5,000 people is required to create a renewable energy standard which promotes renewable energy development, with specific emphasis on rural economic development. Currently, Montana's renewable energy is derived primarily from wind energy, geothermal energy and solar energy. Montana offers many tax incentives and loan programs for individuals and businesses to promote renewable energy development at all levels in both the private and the public sector. This renewable-energy promoting legislation includes production incentives, utility grants and loans, a green power program, property tax exemptions, and production tax reductions. In 2009, Montana received $10.3 million in federal Recovery Act funding to improve the energy efficiency of state buildings and expand renewable energy use and recycling infrastructure in the state. The funds will also be used for grants to encourage use of new clean energy technologies that have moved into the production phase but are not yet well known or utilized in the state. Montana Department of Environmental Quality (DEQ) will also extend low-interest loans to consumers, businesses, and nonprofit organizations to install various renewable energy systems, including wind, solar, geothermal, hydro and biomass. Wind