Saginaw Bay nutrient impairment designation

Saginaw Bay in Lake Huron is on a proposed list of impaired waters due to nuisance algae blooms.

satellite view of Saginaw Bay
Photo credit: Jeff Schmaltz, MODIS Land Response Team, NASA

The Inner Saginaw Bay is experiencing frequent and widespread cyanobacteria blooms during late summer and early fall months. Due to these blooms, coupled with nuisance algae blooms and other indications like plant and algae growth, the Michigan Department of Environment, Great Lakes, and Energy (EGLE), Water Resources Division (WRD), is planning to include the inner portion of the Saginaw Bay in Lake Huron (the portion of the Bay south of a line drawn between Point Lookout on the western shore to Sand Point on the eastern shore) on its proposed list of impaired waters.

Microcystin, an algal toxin, has been detected during these blooms. These blooms can produce toxins that pose a risk to human and animal health, impair coastlines, and negatively impact communities and business in the region. You may be aware that over the past decade, Lake Erie, as well as many inland lakes, have seen an increase of harmful algal blooms (HABs). The potential impact of HABs are determined by the input of “bioavailable” phosphorus. Total bioavailable phosphorus (TBP) is comprised of dissolved phosphorus and particulate phosphorus, both of which are available for HAB development. The data collected, both recently and in previous years, point to ongoing nutrient impacts to the Inner Saginaw Bay’s ecology and the impairment to the Other Indigenous Aquatic Life and Wildlife designated use.

An impairment means that one or more of Michigan’s designated uses such as irrigation for agriculture, navigation, industrial water supply, fishing, aquatic life and wildlife, fish consumption, and body contact recreation are not being supported. This listing is specifically for impairment of “Other Indigenous Aquatic Life and Wildlife” designated use. The use focuses on the protection of plants and animals and their functions within Michigan’s surface water ecosystems. The list of impaired waters, which will include the inner Saginaw Bay, will be submitted to the U.S. Environmental Protection Agency (USEPA), as is done every two years, for review and approval in the spring of 2022.

How does the process work?

The goal of listing any water body as impaired is the identification of a problem, followed by the development of a plan to return water quality to conditions that support the relevant impacted designated uses. An impaired listing is typically followed by the development of a Total Maximum Daily Load (TMDL), which is a document describing current sources and loads of the responsible pollutant and identifying reduction goals needed to address the identified problem. The need to develop a TMDL for the Inner Saginaw Bay is likely.

Following this impairment designation, next steps in the process will include the need to better understand nutrient loading from streams into Saginaw Bay, including the Saginaw River watershed and numerous smaller tributary systems, as well as internal loading from sources like sediments, plants, algae, and animals within the bay. It is anticipated that adequate loading information will be critical in providing context for potential reductions in future nutrient inputs as goals are developed within the TMDL.

What is Happening in the Bay?

Michigan State University Extension along with the Institute of Water Research at MSU and The Nature Conservancy have been working in the Saginaw Bay Watershed since 2019. The team of educators and researchers have developed a farmer-led network as part of a nearly $1 million grant aimed at implementing nutrient management practices to help prevent the loss of at least 900 pounds of phosphorus. These farmer-led networks are valuable for developing peer-to-peer relationships to share knowledge and resources in order to implement change. Groups are already formed and active, putting the farming community in a proactive position of adopting water quality farming practices in advance of this impairment designation. It is likely that due to this designation more grant dollars will become available to improve research and better identify, support, and implement the mitigation techniques used for water quality both on agricultural and non-agricultural land.

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