Event Title

Research to Inform Nutrient Endpoints in East Canyon Creek, Utah

Presenter Information

Michelle Baker

Location

ECC 203

Event Website

https://water.usu.edu/

Start Date

3-31-2008 11:30 AM

End Date

3-31-2008 11:45 AM

Description

Impairment of freshwater resources because of excess nutrients is a world-wide problem, and establishment of numerical nutrient criteria at local to regional scales is an important thrust of research in water quality. Research tools commonly used in aquatic biogeochemistry have not been used toward this end, but may provide scientifically defensible data to support nutrient criteria, especially at local scales. Accordingly, we addressed relationships among water column nutrients, stream production, and nutrient cycling in East Canyon Creek, Summit/Morgan Counties, Utah. East Canyon Creek has been on EPA’s 303d list since 1992 for elevated concentrations of total phosphorus (TP) and low dissolved oxygen. A total maximum daily load (TMDL) assessment completed in 2000 set the maximum allowable TP concentration at 0.04 mg/L. While efforts to reduce TP in the stream since that time have been generally successful, low DO is still common at some sites in mid-summer. Our research showed that P uptake processes were less efficient at TP concentrations > 0.04 mg/L, which supports the established nutrient endpoint. More interestingly, our results provided several lines of evidence that nitrogen (N) should be considered as a nutrient of concern. First, imbalances between water column and producer stoichiometry indicated N limitation was likely; second, algal biomass increased in response to N amendments; third, nutrient uptake parameters were higher for N than for P at reach scales; and fourth, measures of primary production were more strongly correlated to N cycling rates than P cycling rates. Given that N and P are required to build biomass, a ratio-based approach to nutrient management warrants consideration. When management efforts focus on one nutrient in isolation, the other nutrient may play a greater role in water quality impairment.

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Mar 31st, 11:30 AM Mar 31st, 11:45 AM

Research to Inform Nutrient Endpoints in East Canyon Creek, Utah

ECC 203

Impairment of freshwater resources because of excess nutrients is a world-wide problem, and establishment of numerical nutrient criteria at local to regional scales is an important thrust of research in water quality. Research tools commonly used in aquatic biogeochemistry have not been used toward this end, but may provide scientifically defensible data to support nutrient criteria, especially at local scales. Accordingly, we addressed relationships among water column nutrients, stream production, and nutrient cycling in East Canyon Creek, Summit/Morgan Counties, Utah. East Canyon Creek has been on EPA’s 303d list since 1992 for elevated concentrations of total phosphorus (TP) and low dissolved oxygen. A total maximum daily load (TMDL) assessment completed in 2000 set the maximum allowable TP concentration at 0.04 mg/L. While efforts to reduce TP in the stream since that time have been generally successful, low DO is still common at some sites in mid-summer. Our research showed that P uptake processes were less efficient at TP concentrations > 0.04 mg/L, which supports the established nutrient endpoint. More interestingly, our results provided several lines of evidence that nitrogen (N) should be considered as a nutrient of concern. First, imbalances between water column and producer stoichiometry indicated N limitation was likely; second, algal biomass increased in response to N amendments; third, nutrient uptake parameters were higher for N than for P at reach scales; and fourth, measures of primary production were more strongly correlated to N cycling rates than P cycling rates. Given that N and P are required to build biomass, a ratio-based approach to nutrient management warrants consideration. When management efforts focus on one nutrient in isolation, the other nutrient may play a greater role in water quality impairment.

https://digitalcommons.usu.edu/runoff/2008/AllAbstracts/2