(1,000–2,000 years old) was all clearcut relatively early (around the early 20th century); the predominantly maple-alder successional stage forest is today mature. Evergreens will gradually predominate. Typical trees include deciduous maple, alder, ash, and willow, with madrona, cascere, and evergreen Western Red Cedar, Western Hemlock, Douglas fir, pine, and spruce. Sedges, cattails, and other common indigenous flora fill out the understory and wetland areas, with particularly huge Lady Ferns along the ravine between 105th and 110th streets. A chum salmon run on Pipers Creek was successfully restored in the late 20th Century. Peak season to see returning salmon is November. Environmental Learning Center In addition to the variety of program activities and environmental stewardship, the community-driven Carkeek Park Environmental Learning Center (ELC) is becoming a model for resource efficiency and protection of human health and the environment. Built to the highest standard of the U.S. Green Building Council, sustainable building features of the ELC include: rooftop rainwater harvest for flushing toilets and managing storm water. This is becoming dramatically more attractive for large buildings and as potable water is becoming scarce (and expensive); energy-efficient highly insulated building envelope, intelligent lighting, and natural ventilation (some is rediscovery: natural lighting and ventilation were common before electricity); solar electric (photovoltaic) panels provided by City Light's Green Power program 80% recycling or salvaging of demolition and construction waste; salmon-friendly landscaping, meaning drought-tolerant, native species and increased storm water infiltration; paints and coatings, adhesives, sealants, wood composites and carpeting which protect indoor air quality; recycled content products were used in construction: concrete, backfill, wood composite casework, insulation, and flooring; salvaged materials included peeler logs from a naval building in South Lake Union; and regional materials were preferred, supporting the regional economy and reducing the energy, waste, and pollution associated with transportation (one of the biggest components of fossil fuel and energy use). Due to cuts to the City of Seattle's budget, the ELC closed in 2013. Notes and references See also Daylighting (streams) Vivian Carkeek Water resources Bibliography This page has since been replaced by Further reading Seattle Parks and Recreation: Carkeek Park Broadview, Seattle Nature centers in Washington (state) Parks in Seattle