Thursday, August 7, 2008: 3:20 PM
202 B, Midwest Airlines Center
Background/Question/Methods The Great North American Secchi Dip-In has collected transparency data in the United States and Canada continuously since 1994. Volunteers, both professional and non-professional, collect the data during three weeks that incorporate Canada Day (July 1) and July 4th. More than 38,000 transparency records have been collected on more than 7,000 waterbodies. Although most of the waterbodies are lakes and reservoirs, some sites are on rivers, streams, and estuaries. More than 470 programs, ranging in size from one to more than 1,000 volunteers have participated.
The goals of the Dip-In are to gather credible data on transparency and transparency trends across North America during an event that can be used by volunteer programs to energize existing volunteers and recruit new ones.
Results/Conclusions Probably the most frequent question we encounter relates to whether the Dip-In can generate meaningful data. We have had to justify (1) the use of volunteers, (2) transparency as a useful variable, (3) the utility of a single early-summer event, and (4) the utility of non-random sampling procedures. The logistics of data entry and of facilitating data access data has been addressed by encouraging web-based entry into a database from which data can be extracted via the Web by any interested person.
We use the data to detect trends in transparency, using waterbodies having five or more years of data.We found that only 203 of 1,878 waterbodies had significant changes in transparency, with only 45% of those having decreasing transparency. The reason for the changes continues to elude detection, with no apparent correlation with population trends, land use, or restoration efforts.
We also collect data on the volunteers’ perception of water quality and of the problems they perceive on the waterbody. There is a strong regional effect of ambient transparency on perception of quality. In regions of high transparency, quality is sensitive to changes in transparency; in regions of low to moderate transparency, the relationship is weaker and volunteers are more accepting of low transparency.
Despite dramatic changes in land use and population shifts, few of the monitored waterbodies in North America exhibit significant negative change in transparency. The volunteers themselves exhibit regional attitudes suggesting that water quality is not universally understood as a single standard. User perception may play an important role in attitudes towards urban development or restoration and protection measures.
The goals of the Dip-In are to gather credible data on transparency and transparency trends across North America during an event that can be used by volunteer programs to energize existing volunteers and recruit new ones.
Results/Conclusions Probably the most frequent question we encounter relates to whether the Dip-In can generate meaningful data. We have had to justify (1) the use of volunteers, (2) transparency as a useful variable, (3) the utility of a single early-summer event, and (4) the utility of non-random sampling procedures. The logistics of data entry and of facilitating data access data has been addressed by encouraging web-based entry into a database from which data can be extracted via the Web by any interested person.
We use the data to detect trends in transparency, using waterbodies having five or more years of data.We found that only 203 of 1,878 waterbodies had significant changes in transparency, with only 45% of those having decreasing transparency. The reason for the changes continues to elude detection, with no apparent correlation with population trends, land use, or restoration efforts.
We also collect data on the volunteers’ perception of water quality and of the problems they perceive on the waterbody. There is a strong regional effect of ambient transparency on perception of quality. In regions of high transparency, quality is sensitive to changes in transparency; in regions of low to moderate transparency, the relationship is weaker and volunteers are more accepting of low transparency.
Despite dramatic changes in land use and population shifts, few of the monitored waterbodies in North America exhibit significant negative change in transparency. The volunteers themselves exhibit regional attitudes suggesting that water quality is not universally understood as a single standard. User perception may play an important role in attitudes towards urban development or restoration and protection measures.