Sampling Considerations for Establishment of Baseline Loadings from Forested Watersheds for TMDL Application

Five methods for estimating maximum daily and annual nitrate (NO3) and suspended sediment loads using periodic sampling of varying intensities were compared to actual loads calculated from intensive stormflow and baseflow sampling from small, forested watersheds in north central West Virginia to determine if the less intensive sampling methods were accurate and could be utilized in TMDL development. There were no significant differences between the annual NO3 load estimates using non-intensive sampling methods and the actual NO3 loads. However, maximum daily NO3 loads were estimated less accurately than annual loads. The ability to estimate baseline NO3 loads fairly accurately with non-intensive concentration data is attributed to the small fluctuation in NO3 concentrations over flow and time, particularly during storms. By contrast, suspended sediment exports determined by any of the non-intensive methods varied significantly and widely from and compared poorly to the actual exports for both daily and annual methods. Weekly sampling better approximated actual annual exports, but there were no significant statistical differences among weekly, monthly, and quarterly estimates. Suspended sediment concentrations varied widely within and among storm events, so that accurate estimates of total annual or maximum daily loads could not be obtained from infrequent sampling.     

Restoring the Great Basin Desert, U.S.A.: Integrating Science, Management, and People

The Great Basin Desert lies between the Sierra Nevada Mountains to the west and the Rocky Mountains to the east. Nearly 60% of the area’s deserts and mountains (roughly 30 million ha) are managed by the U. S. Department of Interior’s Bureau of Land Management. This area is characterized by low annual precipitation, diverse desert plant communities, and local economies that depend on the products (livestock grazing, recreation, mining, etc.) produced by these lands. The ecological and economic stability of the Great Basin is increasingly at risk due to the expansion of fire-prone invasive species and increase in wildfires. To stem this loss of productivity and diversity in the Great Basin, the BLM initiated the “Great Basin Restoration Initiative” in 1999 after nearly 0.7 million ha of the Great Basin burned in wildfires. The objective of the Great Basin Restoration Initiative is to restore plant community diversity and structure by improving resiliency to disturbance and resistance to invasive species over the long-term. To accomplish this objective, a strategic plan has been developed that emphasizes local participation and reliance on appropriate science to ensure that restoration is accomplished in an economical and ecologically appropriate manner. If restoration in the Great Basin is not successful, desertification and the associated loss of economic stability and ecological integrity will continue to threaten the sustainability of natural resources and people in the Great Basin.