We have been receiving numerous questions regarding the lower Fox…

A few weeks ago, I provided a weekly update that suggested we would get some rain and that it would provide some temporary relief to the system.  That rainfall came last week quite abruptly, and it did provide temporary relief, but the relief did not stay as long as we all hoped for.  Today as we see the inflows coming into the system from Wisconsin and locally, those inflows are very low once again.  We are at about 1/3 to 1/4 of the normal flows for this time of year.  The Chain is held at a nearly steady level, give or take an inch.  Therefore, nearly everything that comes to our dam and gates, gets released.  The temporary relief is on its waning side and we are slipping back into the realized “Extreme Drought” that this region is in.

During past summers, the soil has been extremely wet and add water to the lake as the groundwater levels are higher than the lake levels.  This year with the dry conditions and groundwater pumping for community water use, that groundwater level is likely well below the lake level.  That means instead of the lake received additional water from the ground, the ground is taking water out of the lakes.  This is occurring throughout the Fox River watershed including all throughout Wisconsin.  Wisconsin has many reservoirs that has this happening and as a result, they are send much less water into Illinois than years past.

Unfortunately, the US Drought Monitor shows that conditions are going to persist through the summer.  We have the Algonquin gate up as much as possible, but water is still able to leave over the fix spillway.  Additionally, Stratton is not a 30’ tall dam like other flood storage reservoirs (Carlyle, Shelbyville) but instead is only about 4-foot water difference which is meant to keep a minimum water level in the Chain of Lakes.  It is not designed to hold significant volumes of water.  If we close all the gates at Stratton and Algonquin, water still leaves the system over the fix crest weirs at both dam sites.

While it is physically possible to send extra water to the Lower Fox for a few days to a week, we would use up all the water in the Chain of Lakes (dropping levels to winter pools) and then no one would be able to boat.  It would be a tremendous economic impact to the area, aquatic impacts, and we would be in violation of state law (McHenry Dam Act).

While we hope flows coming into the system will increase allowing that water to be passed along to the Lower River, we are not able to send more water.  It appears we have a long dry summer ahead of us without any relief forecasted.  If relief is forecasted in the future, we would be passing that along to the Lower River as soon as possible.

Thank you for your comments.  Please know we are doing our best managing the system during this extreme drought condition to ensure the best long-term scenario for the entire system, including the lower river.

Thank you,

IDNR – Office of Water Resources

1 Natural Resources Way

Springfield, IL 62702