Rouge River National Wet Weather Demonstration Project
The Rouge River Project
Bringing the river back to life!

2002 Sampling Data and Trend Analysis

In 2002 the sampling program was in part a continuation of earlier programs, which focused on the collection of data at selected monitoring sites, in order to continue documenting water quality status and trends and to support the Phase 1 Combined Sewer Overflow (CSO) basin performance monitoring and reporting. In addition, the continued monitoring at selected sites in each Storm Water Management Area (SWMA) should help evaluate possible changes in water quality due to other stormwater management practices in each SWMA. The monitoring program in 2002 involved continuous monitoring of water quality (dissolved oxygen and temperature) at eight stations, river level and flow monitoring at 13 stations, and precipitation monitoring at 21 stations. During 2002 no dry or wet weather intermittent sampling was performed in the Rouge River Watershed. Intermittent sampling is planned to resume in 2003 and a plan has been developed to rotate intermittent sampling activities through the seven SWMAs over a five-year period. Additionally in 2002, the RPO and the Michigan Department of Environmental Quality (MDEQ)/Water Division collaborated on several “special studies” during the 2002 season. These studies were performed to determine the impact of watershed development and urbanization on the stream and stream channel.

To view a summary of the hydrologic, water quality, and bacteria (E. coli) findings by SWMA click on the SWMAs in the map below:

TREND ANALYSIS

Dissolved Oxygen Comparative Trend Summary.

Trend analysis results clearly demonstrate that DO concentrations are improving in the Rouge River Watershed during both wet and dry weather conditions. Average DO trend results indicate that most locations are improving during all seasons. The percent of daily DO measurements greater than 5mg/L also show that conditions are improving, particularly in the Lower Rouge River. Average DO trend results are summarized in the 2002 Baseline Data Summary Report in figures similar to those shown below for the linear regression and Seasonal Kendall test showing the proximity to CSO basins and now controlled CSO outfalls. Locations with no statistically significant trend are not shown on the maps.

Dissolved Oxygen All Weather Samples

Regression Analysis of the Daily Average Dissolved Oxygen (mg/L)

Dissolved Oxygen All Weather Samples

Seasonal Kendall Analysis of the Monthly Average Dissolved Oxygen (mg/L)

Trend analysis results for the percent of daily DO measurements greater than the State water quality standard of 5 mg/L also show that conditions are improving, particularly in the Lower Rouge River. In 2002, seven of the eight continuously monitored locations met the State standard more than 80 percent of the time.

A summary of the DO trend analysis results are presented in the figure below for each SWMA. The chart bars represent the average improvement in DO per year for wet and dry weather conditions over the period of available data. The Middle 1 and Lower 1 SWMAs are not represented in the chart because available DO data in these SWMAs was not suitable for trend analysis. DO concentrations have improved substantially at all locations evaluated, with the Lower 2 showing the most improvement of over 0.3 mg/L per year for both wet and dry weather.

E. coli Comparative Trend Summary.

E. coli trend analysis results generally showed improvement directly downstream of most watershed management activities, particularly downstream of now controlled CSO outfalls during wet weather. Some locations were identified where E. coli concentrations may be increasing. These sites were generally located near the headwaters in areas still being developed or in areas still impacted by CSOs. Although improving, most locations are still not meeting State water quality standards for E. coli total or partial body contact recreation.

Trend results are summarized in the 2002 Baseline Data Summary Report in figures similar to those shown below for the linear regression and Seasonal Kendall test showing the proximity to CSO basins and now controlled CSO outfalls. Locations with no statistically significant trend are not shown on the maps.

More improvement is clearly being observed during wet weather conditions, indicating that CSO control projects have resulted in substantial water quality improvements. Most of the potentially degrading conditions during dry weather appear to be in the headwaters where residential and commercial development are generally expanding or areas where CSO outfalls are still uncontrolled. It is evident that State water quality bacteria standards will not likely be attained without continued efforts to identify and remedy sources of bacteria to the river.

E. coli All Weather Samples

Regression Analysis of the Geometric Mean (cfu/100ml)

E. coli All Weather Samples

Seasonal Kendall Analysis of the Geometric Mean (cfu/100ml)

E. coli. The following chart summarizes the E. coli bacteria trend analysis results, by ranking improving trends as Good, degrading trends as Poor, and no statistically significant trend as No Change. The chart presents the percentage of locations in each SWMA that met these criteria as calculated in the linear regression trend analysis using the monthly geometric mean E. coli concentration. The Lower 2 and Main 1-2 are showing the most improvement with an average of 63 percent and 50 percent of the locations improving, respectively.

Last Updated: 7/5/2004

Please address all comments and suggestions about the contents of this Web page to rougeweb@co.wayne.mi.us.

The Rouge River National Wet Weather Demonstration Project is funded, in part, by the United States Environmental Protection Agency (EPA) Grants #XP995743-01, -02, -03, -04, -05, -06, -08 and C-264000-01.