Municipal Guide To Clean Water: Conducting Sanitary Surveys to Improve Coastal Water Quality
What to look for: 3. Land use
Land use is directly linked to water quality. Studies have demonstrated that as the watershed population increases, so does the abundance of fecal indicator bacteria in coast- al watersheds. The land-water interface is not restricted to shoreline areas, but is connected and influenced by land use and activities throughout the watershed, some of which are described below.33, 60, 61
Record the types of land use and activities on the field datasheet and in the sanitary survey database. Some areas may require follow-up investigation to verify (when possible) their impact on water quality.
Depending on the type of land use, record whether or not vegetative buffers are present to trap and filter runoff.
How developed is the shoreline and watershed?
Studies of coastal areas have demonstrated a strong rela- tionship between increased bacterial counts and watershed population, and an even stronger relationship between fe- cal bacteria abundance and developed land within a water- shed. Increased population increases the amount of human sources capable of impairing coastal water quality.33, 34, 60
Are there recreational uses of the shoreline?
Large numbers of people in the water (“bather loads”) and unhealthy beach habits, such as young children without swim diapers and people using the beach/wa- ter as their toilet, can contribute bacteria to coastal waters. Ad- ditionally, studies have shown that bathers can shed significant amounts of Enterococci and S. aureus into the water column.62 Gary Curtis Keri Lindberg
Note the approximate percentage of developed shore- line and estimate the percentage of impervious surface. Impervious surfaces (parking lots, roads, roofs) associ- ated with human population and development inhibit the land’s filtration ability, permitting a larger volume of pollutants to accumulate on the land surface, which are then more rapidly conveyed to waterways.64
Note the presence or absence of vegetative buffers (areas of natural or planted vegetation) located between developed areas and the beach/water body. Vegetative buffers filter pollutants and reduce the flow and volume of runoff reaching the shoreline. Buffers trap polluted runoff, allowing the water to percolate into the ground. Manicured lawns are not buffers.65
Note the average number of bathers and the presence/ absence of restroom facilities. Collecting bacteria samples during peak usage may help illustrate the relationship between the number of beach users and high bacteria levels. Statistical analysis can be conducted to further determine this relationship.63
LaMarr Cannon, Maine NEMO