Significance of Chronic Headwater Stream Impairments in Water Resource Management: A Southern California Case Study

Sources of water resource impairments are well known, however, less Ä?Æ©Ä?nÆ?Žn has centered on the role of headwater streams in ƐƵÆ?Æ?ŽrÆ?nŐ water resource management ŽbÅ©Ä?cÆ?vÄ?ƐÍ? This study qƵÄ?nÆ?Ä®Ä?Ä? the extent to which human-environmental factors contributed to the physicochemical cÅ?Ä?rÄ?cÆ?Ä?rŝƐÆ?cƐ of two headwater tributaries that contribute to a Æ?Ä?rcŽůÄ?Æ?Žn basin and downstream surface Å?ŽwƐ to the Santa Ana River Basin, Southern California. In situ sampling for stream temperature (Ë?C), stream Å?Žw (m/s), nitrate (NO3-), ammonium (NH4+), turbidity (NTU), dissolved oxygen (DO), cŽnÄ?ƵcÆ?vŝÆ?Ç?Í? and pH with lab assessments for E. Coli (EC), total coliform (TC) and total dissolved solids (TDS) occurred during drought and seasonal Æ?rÄ?cŝÆ?ŝÆ?Ä?Æ?Žn cŽnÄ?ŝÆ?ŽnƐÍ? DƵůÆ?Æ?ůÄ? parameters exceeded regulatory standards simultaneously, including NO3- (85-96%), NH4+(49-69%), TDS (78-90%) and TC (32-62%) during dry and wet cŽnÄ?ŝÆ?ŽnƐÍ? ƐƵŐŐÄ?ƐÆ?nŐ consistent impacts to water resources entering the Æ?Ä?rcŽůÄ?Æ?Žn basin [2]. DƵůÆ?vÄ?rŝÄ?Æ?Ä? analysis indicates higher cŽncÄ?nÆ?rÄ?Æ?ŽnƐ of NO3- and DO during storm Å?Žw events, excessive cŽncÄ?nÆ?rÄ?Æ?ŽnƐ of TC, TDS and elevated cŽnÄ?ƵcÆ?vŝÆ?Ç? levels during drought, base Å?ŽwƐ cŽnÄ?ŝÆ?ŽnƐ and the presence of sewer systems also ŝnÅ?ƵÄ?ncÄ? the variability of TC and NO3- [3]. Results suggest the frequent (>monthly) monitoring and qƵÄ?nÆ?Ä®cÄ?Æ?Žn of headwater stream quality prior to entering Æ?Ä?rcŽůÄ?Æ?Žn basins is vital to developing comprehensive, sustainable water resource management strategies.

Author(s): Jennifer B. Alford, Jose Mora

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