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River Watershed Monitoring

River Monitoring

		A river's water quality is affected by the land uses in its watershed. Precipitation that runs off the land and precipitation that enters groundwater ultimately discharge to a river and determine its water quality. Sampling base flow, runoff events, and biota helps to measure the water quality in a river. The Water and Environmental Analysis Lab (WEAL) provides individuals and groups several options to help meet the needs of river/watershed monitoring and studies.  These programs focus on providing data and educational information to help understand and manage rivers/watersheds.
WEAL offers a river package which provides lab services, assists in sampling techniques, grant preparation, performs river/watershed studies, study design, and interprets data for river/watershed groups interested in a detailed summary of the condition of their river.  River Monitoring Package:  ammonium nitrogen chloride Nitrate+Nitrite N reactive phosphorus total Kjeldahl nitrogen total phosphorus total suspended solids

Baseflow - Sampling Background

Base flow quality is measured during low flow periods (usually summer and winter) when surface runoff is minimal. Winter is a particularly good time to measure base flow conditions because cold conditions slow the biological transformation of nutrients. Besides giving an indication of stream health, base flow quality can provide a good measure of a watershed’s groundwater quality. For instance, samples for nitrate and pesticide analyses taken during base flow conditions may indicate the amount of these pollutants that enter a watershed’s groundwater.
			For most streams, base flow conditions may be sampled during a period when there has been no significant thawing or precipitation for at least three days. Samples are obtained by grab method. Measuring stream flow during these sampling events is desirable as it allows groundwater discharge to be quantified and is useful in delineating the land area contributing groundwater flow to the stream.
Sample sites should represent all major tributaries in the watershed. It is preferable to locate these sites immediately above bridges or other easily accessible locations. Ideally, stream flow measurement sites should have open water during the winter; therefore, selecting sites with high velocities and sampling in early winter is advised. On larger tributaries more than one sample site may be desirable to document changes in water quality that may occur from the headwater of the stream to near the mouth of the stream.

Potential benefits from the use of base flow sampling:
   Determine nutrient and pesticide inputs to streams from groundwater discharge.

   Provide information to focus time and money to the sub-watersheds that are having the greatest impact on water quality.

   Assess the average groundwater quality within different sub-basins.

   Evaluate which land use practices are affecting stream water quality via groundwater flow.

   Monitor groundwater quality trends within a watershed over time.

Sampling Design

		For most streams, base flow conditions may be sampled during a period when there has been no significant thawing or precipitation for at least three days. Samples are obtained by grab method. Measuring stream flow and/or staff gages when samples are collected is desirable.
Sample sites should represent all major tributaries in the watershed. It is preferable to locate these sites immediately above bridges or other easily accessible locations. Ideally, stream flow measurement sites should have open water during the winter; therefore, selecting sites with high velocities and sampling in early winter is advised. On larger tributaries more than one sample site may be desirable to document changes in water quality that may occur from the headwater of the stream to near the mouth of the stream.

Runoff Event - Sampling Background and Design

Runoff event monitoring has historically been the focus of many stream sampling programs, but many problems are associated with it. Stream flow and contaminant concentrations vary from season to season and throughout any individual runoff event.

Continuous event samplers that are triggered automatically and collect samples throughout an entire runoff event are the best tool for getting quantitative water quality information, but these are very expensive. As a result, continuous event samplers are used in few watersheds and then only on main tributary sites. We have modified a device called a siphon sampler which automatically collects a sample whenever a predetermined rise in water level occurs. This allows all tributaries to be sampled at similar rises in water level and enables better comparison of water quality conditions throughout a watershed.  Siphon samplers are available for University of Wisconsin Stevens Point research projects lab.