|
Spring Phosphorus Loading As winter gives way to spring, melting snow and seasonal rainfall reconnect the surrounding landscape with nearby lakes and streams. During this time, nutrients that have accumulated across the watershed—especially phosphorus—are transported into surface waters through runoff and drainage pathways. This process, known as external loading, is a major driver of nutrient buildup in lakes. Sources of phosphorus include fertilizers, soil erosion, stormwater runoff, septic systems, and organic material entering waterways. While spring runoff introduces new phosphorus each year, many lakes also contain significant amounts of “legacy” phosphorus that have built up in sediments over decades.  Internal Phosphorus Loading Once phosphorus enters a lake, much of it settles to the bottom and becomes part of the sediment through the breakdown of aquatic plants, algae, and other organic matter. Over time, this creates a long-term reservoir of phosphorus within the lakebed. During the summer months, many lakes form distinct layers, with warmer water at the surface and colder water near the bottom. This layering limits mixing and reduces the amount of oxygen reaching deeper waters. As oxygen levels decline near the lake bottom, conditions can become hypoxic or anoxic. Under these low-oxygen conditions, phosphorus that was previously bound in the sediments can be released back into the water column. This process, known as internal loading, makes phosphorus available again for algae and cyanobacteria growth. As a result, lakes with a history of phosphorus accumulation may continue to experience water quality problems, even if new phosphorus inputs are reduced. Why This Is a Concern Excess phosphorus can lead to eutrophication, a process characterized by excessive algae growth and declining water quality. In some cases, these conditions can support harmful algal blooms that produce toxins such as microcystin. These blooms can impact recreational use, create unpleasant conditions, and pose risks to people, pets, and wildlife. Additionally, increased algae growth and decomposition can reduce oxygen levels in the water, placing stress on fish and other aquatic organisms and disrupting the overall balance of the ecosystem. What You Can Do: Protecting Our Lakes Starts at Home
While spring runoff is a natural process, the amount of phosphorus entering our lakes is heavily influenced by everyday activities across the watershed. Small changes in how we manage our properties can make a meaningful difference in reducing nutrient pollution. Simple practices—like minimizing fertilizer use, maintaining healthy shoreline vegetation, managing yard waste properly, and ensuring septic systems are functioning correctly—can all help limit the amount of phosphorus that reaches our waterways. Reducing soil erosion and slowing stormwater runoff are also key steps in keeping nutrients on land and out of the lake. Because everyone in the watershed plays a role, collective action is one of the most effective ways to protect water quality. To learn more about practical steps you can take, visit our Best Practices page for guidance, tips, and resources to help protect and improve our lakes.
0 Comments
 The 2026 lake monitoring season is officially underway across the Marble–Coldwater Chain of Lakes, marking the start of tracking water quality and lake health.
Volunteer Jack Sanderson of Coldwater Lake recently kicked off the effort by paddling nearly eight miles round trip to collect water samples from the deep basin of Coldwater Lake. Heading out early last week, Jack was able to beat the high winds that moved in later in the week. The samples will be analyzed for phosphorus levels, a key nutrient that can influence algae growth and overall lake health. These early spring samples are collected as part of the Michigan Cooperative Lakes Monitoring Program (CLMP). Spring sampling is especially important because it measures phosphorus concentrations before summer algae growth begins, helping scientists and lake managers understand nutrient levels and track long-term trends. This same testing effort is underway on several other lakes in the chain, including First, Marble, Archer, Bartholomew, Mud, and Long Lakes. Sampling on those lakes is being coordinated by volunteer Greg Cavey, who is leading the monitoring effort with volunteers on each lake. While volunteers on those lakes were prepared to collect samples over the weekend, strong winds and rough water conditions delayed their monitoring efforts. Volunteer lake monitoring provides critical data that supports ongoing water quality protection efforts and helps guide future watershed management planning for the entire chain of lakes. A great big THANK YOU to these volunteers!     The Marble-Coldwater Clean Water Partnership is an independent nonprofit corporation formed to protect and preserve the water quality of the Marble–Coldwater Chain through science-based planning and coordinated community action.
Protecting a watershed requires cooperation. Water does not recognize property lines or association boundaries. For that reason, the Clean Water Partnership works in coordination with local lake associations, government partners, and community stakeholders to advance long-term protection strategies for the entire chain. Our Purpose Our purpose is to develop and implement a comprehensive, science-based Watershed Management Plan that safeguards water quality, protects aquatic habitat, supports property values, and preserves the long-term health of our lakes. This watershed plan will serve as a roadmap. It will:
How We Are Funded The Marble-Coldwater Clean Water Partnership is funded solely through voluntary contributions. We are not a membership organization and do not collect dues. Our work depends entirely on donations from individuals, businesses, and foundations who believe in protecting the lakes we all share. We will be applying for grants to support implementation projects. However, grants require preparation — technical studies, watershed analysis, data collection, and matching funds. Before we can secure outside funding, we must first raise the funds necessary to prepare strong, competitive grant applications. Local investment today positions us for larger funding opportunities tomorrow. Working Alongside Our Lake Associations Two key community partners in this effort are:
If you are not already a member of one of these associations, we encourage you to visit their websites and consider joining:
Stronger Together The Clean Water Partnership focuses specifically on watershed-level planning and long-term water quality protection — work that benefits every resident, visitor, and property owner across the Marble–Coldwater Chain. Clean water requires planning, collaboration, and community investment. Together, we can protect what makes our lakes so special — today and for generations to come. The Marble-Coldwater Clean Water Partnership is excited to announce the launch of our new Facebook page!
This page will serve as a central hub for updates, educational resources, project announcements, volunteer opportunities, and ways you can get involved in protecting water quality across the Marble–Coldwater Chain of Lakes. Help Us Build Our FollowingAs a grassroots effort, our success depends on community engagement. You can help by:
If you are part of a lake association or local organization, please consider sharing the page there as well. The more people who see our posts, the stronger our outreach will be—especially as we prepare to launch our upcoming community survey. What’s Coming NextOur next major outreach effort will invite residents and lake users to participate in a watershed survey. Before launching it, we’re working to build awareness so that when we ask for input, our community is ready to respond. Every follow and share makes a difference. 👉 Click here to view and follow our new Facebook page: https://www.facebook.com/profile.php?id=61588401280613 Together, we can protect and preserve the Marble–Coldwater Chain for generations to come. |
Protecting our lakes doesn’t happen on its own.
Every contribution helps protect and improve our lakes. Archives
September 2026
Categories |
|
Visit Our Facebook Page
Copyright © 2025
|
|