Patterns Observed by Nationally Assessing 303(d) Waters In or Near National Forest Lands

We analyzed co-occurring Clean Water Act Section 303(d)-listed (state-assessed as impaired) waters and National Forest properties in an effort to estimate the implications of the 303(d) list for US Forest Service (USFS) impaired waters management and assist restoration planning on public lands. The assessment summarized 303(d) waters on or near National Forest lands by water body type and general source of impairment. We found that 3,066 section 303(d) waters occur within or near National Forest lands. Data were aggregated and assessed at the individual state as well as national levels. We summarized findings in a number of different ways with implications for seeking efficient, regional or national-scale planning and assistance to guide or complement local-scale TMDL efforts in forested lands. We noted patterns reflecting variability among states' leading impairments, regional clustering by impairment type, and overall national frequency by pollutant source or impairment type. For example, we found that over 60% of 303(d)-listed waters on or near USFS lands were clustered in just four states, and several top impairment types (temperature, sediment, habitat modification, mercury, and metals) were concentrated within one or a few states rather than widely distributed among all National Forests. The findings of this assessment can help efforts to focus public lands forestry sector-related water quality planning and assistance at regional and state scales based on the frequency, types and distribution of impairment patterns revealed.