We glimpse the future under a changed climate

Weeks of air temperatures above 90 degrees F have lots of people talking about extreme weather and the role of climate change. Such extreme heat yields myriad human and environmental effects.  A previously unexplored effect is the stress that court-established water levels on lakes will have on the Huron River system under drought conditions that are projected by climate scientists to occur with greater frequency over the next 30-50 years.

This structure increases or decreases the rate at which water leaves a lake.

State laws at odds

Michigan law prohibits reduced river flows under Section 324.301 of the 1994 Natural Resource and Environmental Protection Act. The section states that diminishing an inland lake or stream is prohibited without a permit.  “Diminish” means to reduce flows to a creek, as happens when gates of a lake level control structure are closed.

However, read a bit further and you’ll see that Michigan law allows for reduced river flow under Section 324.307.  Under this law, lake residents are allowed to obtain a regulated lake level by building a lake-level control structure that maintains a lake’s water level while reducing flow to downstream lakes and rivers.  Lake residents are motivated  to pursue lake levels to make it easier to boat, recreate in the lake, and build docks that they can reliably use despite changes in weather conditions. Many lakes in the watershed, including in-line lakes that are impoundments of the Huron River, have court-ordered lake levels.

Lake residents are able to obtain these designations through a process with the Michigan Department of Environmental Quality (DEQ).  Once a lake level is set by a judge, then the county government (often the Drain or Water Resources Commissioner) is responsible for altering the outflow of the water from these lakes via structures so that the the lake is able to maintain a constant depth. Dams are one type of structure used to control flows. Other structures like the one pictured above also are present in the watershed.

Typically, though not always, the DEQ gives section 307 precedence over section 301, meaning that permitted lake-control structures are allowed to diminish the downstream lake or stream in order to maintain their lake levels.

Keeping a lake level in drought conditions

Maintaining a court-ordered lake level may go unnoticed during periods of normal or wet weather. But this manipulation of a natural system has the potential to stress the ecology of the downstream river during drought periods. Since the county is obligated to maintain a certain water level it is possible that they would need to “hoard” incoming water and only allow reduced flow —  or even no flow — downstream.  The graphics below show a simple input and output system to illustrate the issue.

Under normal conditions, the amount of water entering a level-controlled lake will approximately equal the amount of water leaving the lake.

Under typical flow conditions, the amount of water entering a lake will equal the amount of water leaving the lake, plus any additions from rain, and minus any water lost through evaporation.  Under drought conditions, the amount of water entering the lake is already reduced from low stream flows, no additional input is provided from rain, and the amount of evaporation can be significantly high.  As a result, it is possible that the county would have to close the gates altogether to maintain the lake’s court-ordered water level, and no water or very reduced flows will reach downstream to keep the fish alive or provide water to the next lake or river section downstream.

The drought situation– in order to maintain the lake level, water is held back in the impoundment.

How can the situation be improved?

For the waterfront resident

Given the current hot and dry conditions in southeastern Michigan, waterfront residents likely are seeing reduced water flow especially if living downstream of a lake with a court-mandated lake level. Understandably, this imbalance of “water power” may feel unfair and residents could be looking for a fast and easy solution to secure more water for their section of the river or lake. Such a solution doesn’t exist. Aggrieved residents have sought justice through our legal system. Typically, these cases are eventually dropped since droughts end and rain, and consequently higher water flow, mute the problem.

Yet, droughts are predicted to become more common and more severe over the next several decades, and we may see a resurgence of court cases.

A measure of relief may be found in the operation of the structures. Some lakes have an ungated pipe or dam bypass that drains downstream, so that some amount of water is always flowing downstream, even when the dam’s gates are completely closed. However, such a bypass is not a requirement in obtaining the establishing a legal lake level.  Building this in a requirement would be an important and wonderful safeguard to ensure that some level of water is always going downstream.

And for the river

The DEQ has the responsibility to examine the problem with stream flow as it relates to drought and mandated lake levels. In particular, giving the priority of maintaining lake levels over allowing for run-of-the-river flows is dangerous for the survival of downstream ecosystems when facing drought situations.

After speaking with DEQ staff, I am happy to report that the issue is on their radar and under consideration.  HRWC will keep an eye on this complex issue at the state level, and work with local partners to find workable solutions to this increasingly urgent problem.