. Critical trends assessment program : keeping an eye on Illinois habitats. Critial trends assessment program; Habitat conservation. streams- .-, ^-^ stonefly .he rivers and streams of Illinois travel approximately 87,000 miles across our landscape. Before the arrival of European settlers, most Illinois streams had meandering courses, natural vegetation, and associated rich wetlands. Since then, agricul- ture and development have promoted draining of wetlands, made streams more cloudy, and straightened (channelized) and levied stream channels. While these stream "improve- ments" have
. Critical trends assessment program : keeping an eye on Illinois habitats. Critial trends assessment program; Habitat conservation. streams- .-, ^-^ stonefly .he rivers and streams of Illinois travel approximately 87,000 miles across our landscape. Before the arrival of European settlers, most Illinois streams had meandering courses, natural vegetation, and associated rich wetlands. Since then, agricul- ture and development have promoted draining of wetlands, made streams more cloudy, and straightened (channelized) and levied stream channels. While these stream "improve- ments" have grown a vibrant economy, they have done so at the expense of many aquatic species, including freshwater mussels, environmentally sensitive aquatic insects, and fish. The abilit)' of Illinoisans to recreate in and to obtain drinking water from the state's streams has also declined. nymph;; 'M Statewide Stream Quality* CTAP's random sampling design and large number of sites (149 sites, Fig. 1) allows for powerful statements to be made about stream quality across the state and in various regions. CTAP assesses streams of all sizes and qualities in proportion to their occurrence across the landscape. Since much ot the state has been dramatically altered, the streams also appear heavily altered. Table 8 provides a brief explanation of the environ- mental indicators used by CTAP to assess stream condition. Results of Statewide Monitoring ⢠EPT taxa richness was heavily affected by channelization. Streams with meandering channels had 40% greater rich- ness than did channelized streams (Fig. 20). ⢠The effect of channelization on EPT remained constant over all stream sizes. (Fig. 21). ⢠HBI (Hilsenhoff Biotic Index) did not var)' appreciably across the state, probably as a result of the historical loss of intolerant species. addisfiy larvae. HQI (Habitat Quality Index) was heavily affected by channelization, with meandering streams scoring signifi- cantly lower than channeliz
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