The IUGLS final report on the St Clair river was released on Tuesday and -- no surprises -- the study board is sticking to its recommendation that no remedial action be taken at this time.
The study board has also backed off on its previous water loss numbers (5% increase in conveyance, 10 cm drop and 6 billion gallons per day increased outflow) preferring now to avoid speaking in terms other than a 7 cm - 14 cm decline in water levels. The numbers, however, are still reported in the final document. Ted Yuzyk, the Canadian co-chair of the study, told media that the previous numbers "were made up and not credible." The IUGLS board members are also quoted as saying that the work done in the Baird report is "bunk".
The study board concludes that:
- There has been no significant erosion of the channel in the upper reach of the St. Clair River bed since at least 2000.
- There has been a 23 cm (9 in) decline in head difference between Lake Michigan Huron and Lake Erie from 1963 to 2006
- Based on 15 different analyses, an increase in the river’s conveyance capacity accounts for 7 to 14 cm (2.8 to 5.5 inches) of the decline in head difference between Lake Michigan‐Huron and Lake Erie from 1963 to 2006 ; however, this change is not ongoing and there has been a slight decrease in conveyance capacity since 2000.
- Climate is the main driver of lake level relationships over time and accounts for 9 to 17 cm (3.5 to 6.7 inches) of the decline in head difference. In particular, hydroclimatic change contributed to a substantial decline in net water supplies to Lake Michigan‐Huron in the most recent decade.
To put in perspective the significance that should be placed on the post 1971 increased outflow in the St Clair river, the diversion from Lake Michigan at Chicago is about 2 billion gallons per day and has a Supreme Court ruling attached to it. That diversion is currently under review after a number of states demanded that the US Supreme Court reopen the diversion ruling. GBF along with numerous other organizations support introducing control measures in the middle Great Lakes now and believe that the lengthy timelines (20 years) of these projects warrant an immediate start.
