Water: Monitoring & Assessment
3.2 The Visual Assessment
To conduct the visual stream assessment portion of the watershed survey, volunteers regularly walk, drive, and/or canoe along a defined stretch of stream observing water and land conditions, land and water uses, and changes over time. These observations are recorded on maps and on visual assessment data sheets and passed to the volunteer coordinator, who can decide whether additional action is needed. Volunteers might themselves follow up by reporting on problems such as fish kills, sloppy construction practices, or spills they have identified during the visual assessment.The basic steps to follow are:
Task 1 Determine the area to be assessedThe visual assessment will have most value if the same stream or segment of stream is assessed each time. In this way, you will grow familiar with baseline stream conditions and land and water uses, and will be better able to identify changes over time. You should choose the largest area you feel comfortable assessing and ensure that it has easy, safe, and legal access. The area should have recognizable boundaries that can be marked or identified on road maps or U.S. Geological Survey topographic maps. This will help future volunteers continue the visual assessment in later years and help the program coordinator easily locate any problems that have been identified.
Once you have identified the area to be assessed, define it clearly in words (for example, "Volunteer Creek from Bridge over Highway One to confluence of Happy Creek at entrance to State Park"). Then, either draw the outline and significant features of the stream and its surroundings on a blank sheet of paper or obtain a more detailed map of the area, such as a plat, road, or neighborhood map. This will serve as the base map you will use to mark stream obstructions, pollution sources, land uses, litter, spills, or other problems identified during your visual assessment.
Task 2 Determine when to surveyBecause land and water uses can change rapidly and because the natural condition of the stream might change with the seasons, it is best to visually assess the stream or stream segment at least three times a year. In areas with seasonal changes, the best times to survey are:
- Early spring, before trees and shrubs are in full leaf and when water levels are generally high
- Late summer, when trees and shrubs are in full leaf and when water levels are generally low
- Late fall, when trees and shrubs have dropped their leaves but before the onset of freezing weather
Again, it is important to survey the stream at approximately the same time each season to account for seasonal variations. You might find it productive to drive through the watershed once a year and to walk the stream (or the stream's problem sites) at other times (see Tasks 4 and 5).
Task 3 Gather necessary equipmentIn addition to the general and safety equipment listed in Chapter 2, the following equipment should be gathered before beginning the visual assessment:
- Reference map such as road map or USGS topographic map, to locate the stream and the area to be assessed
- Base map to record land uses, land characteristics, stream obstructions, sources of pollution, and landmarks
- Field data sheet
- Additional blank paper, to draw maps or take notes if needed
- Relevant information from background investigation (e.g., location of NPDES outfalls, farms, abandoned mines, etc.)
Task 4 Drive (or walk) the watershedThe purpose of driving (or walking) the watershed is to get an overall picture of the land that is drained by your stream or stream segment. It will help you understand what problems to expect in your stream, and it will help you know where to look for those problems.
Remember never to enter private property without permission (see section 2.3 - Safety Considerations).
As with all other monitoring activities, you should undertake your watershed drive or walk with at least one partner. If you are driving, one of you should navigate with a road map and mark up the base map and field sheet with relevant discoveries while the other partner drives. You might want to pull over to make detailed observations, particularly near stream crossings.
As you drive or walk the watershed, look for the following:
- The "lay" of the land--become aware of hills, valleys, and flat terrain. Does any of this area periodically flood?
- Bridges, dams, and channels--look for evidence of how the community has dealt with the stream and its flood potential over the years. Are portions of it running through concrete channels? Is it dammed, diverted, culverted, or straightened? Where the road crosses the stream, is there evidence of erosion and pollution beneath bridges? Is streamflow obstructed by debris hung up beneath bridges?
- Activities in the watershed--look for land use activities that might affect your stream. In particular, look for construction sites, parking lots, manicured lawns, farming, cattle crossings, mining, industrial and sewage treatment plant discharges, open dumps, and landfills. Look for the outfalls you identified in your background investigation. Also look for forested land, healthy riparian zones, undisturbed wetlands, wildlife, and the presence of recreational users of the stream such as swimmers or people fishing. (Note that heavy recreational use or large flocks of birds might adversely affect the quality of streams, ponds, lakes, and wetlands.)
Task 5 Walk the streamWhere you have safe public access or permission to enter the stream, stop driving or walking the watershed and go down to the stream. Use all of your senses to observe the general water quality condition. Does the stream smell? Is it strewn with debris or covered with an oily sheen or foam? Does it flow quickly or sluggishly? Is it clear or turbid? Are the banks eroded? Is there any vegetation along the banks? If you see evidence of water quality problems at a particular site, you might want to investigate them in more detail. Drive or walk upstream as far as you can, and try to identify where the water quality problem begins.
Use your field data sheet to record your findings. Always be as specific as possible when noting your location and the water conditions you are observing. Draw new maps or take pictures if that will help you remember what you are observing. Don't be afraid to take too many notes or draw too many pictures. You can always sort through them later.
Take note of the positive conditions and activities you see as well as the negative ones. This, too, will help you characterize the stream and its watershed. Look for such things as people swimming or fishing in the stream; stable, naturally vegetated banks; fish and waterfowl; or other signs that the stream is healthy.
For more information on what to look for in and around the stream, consult Chapter 4 and, in particular, the Stream Habitat Walk.
Task 6 Review your maps/field data sheetsThe last step of the watershed survey's visual assessment is to review the maps, drawings, photos, and field data sheets you have assembled for your stream or stream segment. What is this information telling you about problem sites, general stream condition, potential for future degradation, and the need for additional action? In most cases you will find that you have put together an interesting picture of your stream. This picture might prompt additional monitoring or community activity, or could urge your program coordinator to bring potential problems to the attention of water quality or public health agencies in your area.
When reviewing your data, be sure maps are legible and properly identified, photos have identifiable references, and field data sheets are filled out completely and accurately. Your program coordinator might ask for your field data sheets, maps, and other material and can probably help interpret the findings of your watershed survey.
References and Further Reading
Delaware Nature Education Center. 1996. Delaware Stream Watch Guide. July.
Ely, E. 1994. Delineating a Watershed. The Volunteer Monitor. 6(2):3.
Ely, E. 1994. LandUse Surveys. The Volunteer Monitor. 6(2):19.
Gordon, N.D., T.A. McMahon, et al. 1992. Stream Hydrology: An Introduction for Ecologists. John Wiley and Sons.
Kerr, M. and V. Lee. 1992. Volunteer Monitoring: Pipe Detectives Manual. March 1992. Rhode Island Sea Grant, University of Rhode Island, Coastal Resources Center.
Kerr, M. and V. Lee. 1992. Volunteer Monitoring: Shoreline Mapping Manual. March. Rhode Island Sea Grant, University of Rhode Island, Coastal Resources Center.
Maryland Save Our Streams. Watershed Survey, Stream Survey, and Construction Site Inventory (packets). Maryland Save Our Streams, 258 Scotts Manor Drive, Glen Burnie, MD 21061.
Trautmann, N. and E. Barnaba. 1994. Aerial Photographs A Useful Monitoring Tool. The Volunteer Monitor. 6(2):17.
University of Rhode Island. 1990. Rhode Island Watershed Watch: Shoreline Survey Manual for Lakes, Rivers, and Streams. Draft. June.
Yates, S. 1988. Adopting a Stream: A Northwest Handbook. Adopt-A-Stream Foundation. University of Washington Press.
Watershed Survey Visual Assessment (PDF, 15.0 KB)
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