Lakes Management in Medford Lakes

There are twenty one lakes in Medford Lakes, which are actively managed through the Medford Lakes Colony.  Many of our lakes have challenges due to water flow rates, accumulation of organic on lake beds, and runoff carrying waste items lying on roadways and private property.  The Colony applies a series of various management techniques to help improve the water quality within our lakes.

Medford Lakes Colony and Water Quality Management

There are 21 lakes of varying sizes within Medford Lakes. As important background information for this review of lake management, these 21 lakes are part of two distinct drainage areas, its local watershed. The most important differentiator of these drainage areas is their relative size. 

 The Aetna lakes drainage area is five times the size of the Mishemokwa drainage. While there may be subsurface differences in the land under these two areas, the key factor is that five times as much surface water from rainfall and snow melt flows through the Aetna flow as through the Mishemokwa lake chains. Flow rates play a crucial role in water quality and subsequent needs for water quality management.

Factors Affecting Water Quality

There are a broad range of factors that impact surface water quality, but we will focus on four key topics. 

1.  The largest influence on water quality is overall flow rates into and through lakes. Fresh, moving water brings improved temperature (T) and oxygen (DO) levels critical for fish habitat and the overall lake biome. High water flows also drive natural stirring of the water and of T and DO throughout the water column. In warm summer months, very slow-moving water, and especially water that stops flowing completely, has a natural tendency to undergo both T and DO stratification where surface water gets very warm and water near the bottom of the lake can be much colder. One can find T differences of 15 degrees F and 20% differences in DO levels in water that is only 8 feet deep. Below is a brief discussion of the impact of temperature and DO levels on what is one of the most important chemicals, phosphorous (P), found in lakes.
2. Chemical Changes The presence of oxygen allows many important chemical reactions to occur in water. For example, in well-oxygenated lakes dissolved phosphorus (phosphate) and iron combine to form an iron-phosphate precipitate that settles to the lake bottom. This is a very important chemical process that removes phosphorus from the water column, but it only occurs when oxygen is present. However, if lake water becomes anoxic (oxygen-deficient), often seen in the lower layer of water in a stratified lake, which is typically cooler than the water above and relatively stagnant (the hypolimnion), the iron-phosphate bond breaks and phosphorus is released back into the water from the lake sediments. This process is called internal phosphorus loading and can be a significant internal source of phosphorus loading to lakes.

Source: Indiana Department of Environmental Management – Office of Water Quality

Controlling and managing the amount of phosphorus in lakes is critical as it the “limiting factor” in the growth of algae.

1. The second largest source of water quality problems is the stormwater management model for Medford Lakes. There are more than 100 storm water drains throughout the town. (see the map below) While many municipalities have systems that collect this water and send it to a water treatment facility, in Medford Lakes, the rainwater, and everything it carries, from each of these storm drains flows directly into one of our lakes.   Fertilizers applied to lawns across town can be carried by heavy rains into the lakes. As mentioned above, phosphorus is a major negative factor in lake water quality. A very beneficial factor in our favor is the longstanding Borough ordinance banning the use of fertilizers containing phosphorus, the middle number in the 5-10-5 string found on bags of fertilizer. To the extent that homeowners and landscapers follow this ordinance, stormwater can be a small factor in “external load” phosphorous flowing into the lakes. 

 While the flow of phosphorus from stormwater has potentially been minimized, nitrogen, the first of the three numbers on the bag of fertilizer, is not banned and, while not as potent a problem as phosphorus, it is a nutrient that still can negatively impact water quality by driving growth of algae. 

Everything else that accumulates on our roadways will also get carried into the lakes. Whether it is dog waste that is not cleaned up but the owner, natural leaf litter or oil drippings, there are many “things” on our roadways waiting for a good rain to wash them into a lake.

1. Number three on our list of issues is organic material accumulated on the bottom of the lake. Nearly all the lakes in Medford Lakes are surrounded by trees. Every fall likely half the leaves those trees lose wind up in the lake where they will sink to the bottom. After 20 or 30 years of this process, a layer of decomposing leaves can grow to two feet or more in thickness. This organic material is a rich source of nutrients, such as nitrogen and phosphorous, with these nutrients being a key “food item” for algae in the lake. As the organic material decomposes it releases these nutrients back into the water. A healthy lake will always contain some well-balanced level of nutrients and algae supporting beneficial biochemical processes in the water. The problem comes when the volume of nutrients grows to a level that upsets the beneficial balance resulting excessive growth of algae. 
2. Our fourth issue is the seasonality of water flows. With its relatively tremendous watershed size, and resulting high volume of water flowing, there are few water quality problems in either Upper or Lower Aetna lakes. Even in the driest of summer months water is flowing in large volume over the spillways. High flow rates bring fresh oxygenated water, adequate mixing / stirring of the water reducing T and DO stratification. The large surface area relative to tree-lined shoreline means much reduced buildup of organic material reducing the chance for decomposing to release excess nutrients and the resulting algae growth. High flow rates mean leaf litter has a better chance of breaking up and flowing downstream before it can sink to the bottom.

The Mishemokwa chains of lakes, with their much smaller watershed area and resulting lower water flow rates, are where water quality issues are most significant within the Borough. During the driest and warmest months of summer, the water levels in many of these lakes drops to a point where water completely stops flowing over their exit spillways. This results in what some lake management people call a “dead pool” model. The water sits, baking in the sun and heat with little or no mixing of T and DO. Reduced oxygen levels at the bottom of the lake can cause an increase in the release of nutrients, particularly phosphorus, from the thick layer of decomposing “muck” driving increased potential for algae blooms. 

The Colony’s Water Quality Management actions

There is nothing that can be done to change the size of watersheds or the resulting water flow volumes. Our lakes are at the mercy of weather, our rainfall and snowfall. But the Medford Lakes Colony has three programs at varying stages of completion to address other problems.

1.  The lakes in the Mishemokwa chains, with their smaller size relative to shoreline and tree cover and much lower, sometimes zero, water flow rates, have accumulated the thickest layers of organic material, muck. For the past eighteen years the Colony has hired an outside contractor to physically remove the muck from coves in many of the lakes. This early stage muck removal, while beneficial, has been done by hand and therefore limited in its impact.  In the past two years the Colony has significantly increased this muck removal process by hiring a contractor with a “hydro-rake” that can remove as much as 100 cubic yards of muck in a week from a single lake. This enhanced hydro-raking will be the primary “de-mucking” tool to be used in the future. Four of the sixteen lakes that are key candidates for hydro-raking have had this work done. Budget constraints will limit future hydro-raking to three lakes a year. It will take several years before each lake has been cleaned with the hydro-rake. After the initial hydro-raking, long term maintenance level hydro-raking will be much easier.
2. During summer month “dead pool” periods, when the lake levels drop below the exit spillway levels, there is no water flow into or out of many lakes. No natural mixing of the water results in T and DO stratification and potential for increased release of P nutrient into the water causing algae blooms. Several years ago, the Colony started a program to install aeration systems in all the Mishemokwa chain lakes. Prior to 2023 four lakes had these systems installed. Installation in all or parts of seven more lakes was completed in the fall of 2023. Subject to budget constraints, all candidate lakes should have aeration systems by the end of 2025. These systems consist of an air compressor connected to one or more diffusers which are placed on the bottom of the lake at strategic points. The constant flow of air bubbles released from these diffusers creates an upward convection current in the water surrounding each bubbler. Water from the bottom of the lake gets pulled to the surface by this bubble-generated current. At the surface it warms and absorbs oxygen. As the cold bottom water gets pulled to the surface it gets replaced by warmer, more oxygenated water. These aeration systems can completely defeat the T and DO stratification, and all the negative effects, that would otherwise naturally take place. 
3. In the summer of 2023 the Colony introduced a new level of technology into the battle against algae growth, the use of “ultrasound” waves to control growth of algae. These ultrasound devices use sounds waves to indirectly kill off certain varieties of algae before they have the chance to mature and grow into dangerous blooms. These devices have been installed in two lakes so far. If their positive impacts continue, as has been seen so far, more devices will be installed in all the Mishe-Mokwa chain lakes.
4. To address the issue of stormwater flows into the lakes, in the past the Colony has created several Rain Gardens on Colony property. Rain Gardens are recognized nationally as a Best Management Practice (BMP) for managing stormwater flows. A Rain Garden is a shallow landscaped area that collects water from impervious surfaces, areas that do not allow the water to soak through into the ground, such as roads, parking lots, driveways and roof tops. Often the water from these surfaces can get polluted before flowing into lakes and streams. 

They are designed to blend two important goals: aesthetics and water quality. They can be blended into the landscape and made to look natural. Water captured in a rain garden will percolate into the ground where the natural water cleansing capabilities of the soil and rock will remove the pollutants.

You can also add a Rain Garden to your own property and find out more about Rain Gardens and how to build them here.