The Alabama Department of Environmental Management (ADEM) has recently released an interesting presentation about nutrient management for Alabama rivers and lakes that demonstrates much-needed progress in coping with the problem of nutrient pollution.

The opening slides of the presentation describe programmatic approaches that have resulted in these impressive improvements.  A short history of the adoption of Numeric Nutrient Criteria for forty Lakes and Reservoirs and adoption of Nutrient Total Maximum Daily Load (TMDL)s for 32 stream segments is followed by a series of nutrient management case studies.

Read the Report: “Alabama Successes in Nutrient Management Jan 2020”

An Interpretation of the Results

Of particular interest for those of us who love the Cahaba River, beginning on slide 24, is the Cahaba River Case Study.  Slides 32 to 34 show how phosphorus at three monitoring locations in the upper Cahaba are now meeting the Nutrient TMDL in-stream phosphorus target of 0.035 mg/l.

One of the important problems associated with excessive phosphorus discharges is the wide dissolved oxygen (DO) swings the river experiences through the day, with high DO during the day, followed by low (too low) DO at night.  Slides 35-39 show how those diurnal cycles (24 hour cycles) have come back to more normal values since ADEM has focused on nutrient management.

Our Conclusion

The Cahaba and many other Alabama streams have suffered from excessive nutrient loading over the past 30 years, so these results are very good news!  ADEM’s has made a very positive improvement in controlling this serious pollution problem in the Cahaba River.