Conservation Minnesota

A Lake Manager’s Notebook: What Can You Do?

May 2014Dick-Osgood-bio

Professionals involved in lake management often produce “what you can do” or “the top 10 things you can do” advice as a way to engage citizens and lakeshore owners.  However, I think the question should be broadened to “what is it possible to do?” before we point out what individuals can (or should) do.  In many cases, individuals’ and lakeshore owners’ will only be a small part of ultimate solutions.

First of all, what can be done depends on the problems in your lake.  Here, let’s limit our discussion to the problem of excess algae caused by excess phosphorus in the lake – the problem of eutrophication – because this has become the main lake management focus.

There are four categories to consider:

If your lake does not have a problem (not impaired) it means that protecting it from developing problems is the appropriate management strategy.  Then, preventing inappropriate municipal or industrial discharges to the lake or its tributaries is essential.  In addition, preventing or severely limiting land use changes will be required, especially agricultural or urban development.  Some lakeshore development may be permissible, but this should be on large lots with significant setbacks along with minimum land disruption and adequate sewage treatment.

What can you do and what should be done in these cases?

1. Vote and be politically active.  Regulatory actions and land use regulations are the largest threat to degrading pristine lakes.  These are political activities.
2. Preserve land.  Either through outright purchase or conservation easement, protect lands from the possibility of inappropriate development.
3. Watch out for additions to the lake’s tributary watershed.  Most impaired lakes’ watersheds have been enlarged through artificial drainage systems.
4. Be a model on your property.  Eliminate or minimize a manicured lawn.  Minimize hard surfaces.

If your lake does not have a problem but is showing signs of degradation (incipient impairment) act quickly and decisively.  This classification is perhaps the most challenging because it is difficult to detect changes in a timely manner.  Nonetheless, here is what can be done for lakes on the edge.

To be responsive to restoration actions, the lake will have these characteristics:

-Have phosphorus concentrations at or below about 25 to 30 parts per billion (ppb)
-Have watershed areas less than about 10-times the lake surface area
-Internal phosphorus recycling (phosphorus accumulated in the lake sediments recycle back into the water) will not yet have been initiated

If any one of these conditions are not met, the lake will probably not be responsive and shifts down to the next category.

There are very few cases where mitigating actions have been implemented and positive lake responses (that is, improvements in and stabilization of lake condition) have occurred.  One case I am familiar with is Deer Lake, Wisconsin.

The Deer Lake Improvement Association (DLIA) had recognized Deer Lake’s approaching problems for several decades.  By the late 1990s, the DLIA took these actions, which serve as “Best Practices” guidelines:

-Established the Deer Lake Conservancy to fund restoration activities.  A permanent, sustainable organization such as this is critical to sustaining a long-term restoration program.
-Converted significant lands (over 140 acres) to prairies, wetlands and ponds.
-Accomplished a 55% reduction in phosphorus inputs over more than 10 years.  The ultimate goal is a 65% reduction.

Deer Lake was fortunate, too.  The lake had not yet become irreversibly eutrophic.  This means it remained responsive to phosphorus reductions.  Also, Deer Lake’s tributary area was small, only 5.6-times the lake’s surface area.  Tributary areas greater than about 10-times a lake’s surface area are usually not practical for restoration actions to be effective.

The successful formula for DLIA and the Deer Lake Conservancy was:

1. Advanced warning.  They had a long history of involvement, including a credible monitoring program.
2. Organization.  They established and sustained a focused management and funding organization.
3. Timing.  They took action while the lake was still responsive.
4. Boldness.  Their actions were substantial in scope and scale.
5. Luck.  The lake remained responsive and the lake’s watershed was small enough to be manageable.

If your lake does have a problem (impaired), your management challenges increase.  Unlike Deer Lake, impaired lakes substantially lose their resilience to improve with watershed phosphorus reductions.  This is due to a number of factors, including:

-Long-term, widespread land use alterations have become “hard-wired.”
-Watershed areas are too large (greater than 10-times the lake surface area) to accomplish the needed phosphorus loading reductions.
-Best management practices, singly and in combination, are insufficient.
-The initiation of internal phosphorus recycling.

Guidelines for improving impaired lakes with watershed areas between 10- and 50- times the lake surface area are:

-Substantial (more than 75%) reductions in phosphorus inputs must occur and these reductions must be sustained.
-Internal phosphorus recycling must be eliminated.

The Yahara Lakes (Mendota Chain of Lakes in Madison, Wisconsin) provide an example of the scope and scale required to improve impaired lakes.

The Clean Lake Alliance was formed recently and is “dedicated to continuously improving and protecting water quality in the Yahara River watershed.”  Their action plan (Yahara CLEAN Strategy Action Plan for Phosphorus Reduction, November 9, 2012) illustrates the monumental effort required to clean up the watershed.  The plan’s goal is to reduce phosphorus loading from agricultural and urban runoff by 50% at an estimated cost of $78,600,000 over 20 years.  It has not yet been determined that the 50% reduction will be sufficient to clean up the lakes.

Comparing this with most watershed restoration efforts tells the story of why our lakes are not improving.  Simply, most efforts are insufficient – too small, too short and too little.

I am convinced it is often misleading to suggest that homeowners and lakeshore owners can “do something” on their properties and reasonably expect to make a meaningful difference in a downstream lake.  The math just does not work in light of the overwhelming need.  Best management practices cumulatively accomplish 10, 20 or maybe even 30% phosphorus loading reduction when reductions of 75% or more are required.

We should certainly not discourage any efforts that landowners can make to improve runoff quality.  But we should also not mislead them regarding the impacts of their actions.  Unfortunately, they will barely tilt the needle.  We owe it to all parties involved to do the math.

There is good news.  Management actions in lakes, called “in-lake management,” can be effective at mitigating the symptoms of eutrophication, often in short time periods and substantially lower costs.  Some people may find this distasteful because with most in-lake management methods, the underlying causes are not being addressed.  The Yahara Lakes case illustrates that addressing the true causes of phosphorus-impaired lakes requires great deals of time and money.  In fact, there are precious few cases in the United States where impaired lakes have been rehabilitated with watershed management alone.

In-lake management provides meaningful outcomes in shorter times and for less money.  Below is a summary of in-lake management techniques that can improve lake condition:

-Aeration or oxygen addition
-Artificial circulation
-Algaecides
-Biomanipulation
-Chemical sediment inactivation
-Dredging
-Nutrient inactivation
-Selective withdrawal

A word of caution: none of these should be implemented without first conducting diagnostic studies, modeling and feasibility studies.  One example I give is the use of aerators – things that make bubbles.  Aerators may be effective, but only if they are appropriate for the problems to be addressed, properly designed and sized guided by engineering studies and properly operated and maintained.  In the vast majority of cases, just putting aerators in lakes is not effective.

In addition, all of these in-lake techniques are ongoing maintenance activities (except perhaps dredging) requiring ongoing inputs of energy, money and continuous monitoring and evaluation.

This may sound onerous, but this is appropriate.  There are very few “quick fixes” or “silver bullets.”  Lake management – watershed or in-lake – is seldom effective when done casually.  As illustrated above, to be effective in these cases, watershed management requires decades and millions of dollars.  On this basis, it is possible to rationally and fairly compare and consider whether to invest in watershed management versus in-lake management.  In many cases, the answer may be both.

Finally, if your lake is super-impaired there are, unfortunately, few practical options.  By “super-impaired” I mean lakes that:

-Have large watersheds (greater than 50-times the lake surface area)
-Have high phosphorus concentrations (greater than about 100 to 200 ppb)
-Have high rates of internal phosphorus recycling

Most watershed and in-lake management options are too ineffectual, too expensive or both.  Public investments in these lakes are unwise and private investments in these lakes are usually futile.

So, what can you do?  Support management actions that are appropriate for your lake and are likely to be effectual.

To summarize, here is what can be done:

-If your lake is unimpaired, the effective strategy is watershed protection and prevention.
-If your lake is on the edge, the effective strategy is aggressive, comprehensive watershed protection and restoration.
-If your lake is impaired, the effective long-term strategy is comprehensive watershed restoration (likely requiring multiple -decades and millions or tens of millions of dollars) and the effective short-term strategy is in-lake management (requiring –appropriate studies and ongoing maintenance).
-If your lake is super-impaired, there is not much that can reasonably be done.

What can you do?  Recognize what it is possible to do and understand your role in a total solution.

About Dick Osgood

Dick Osgood
Dick Osgood has authored numerous scientific journal papers, made hundreds of presentations at professional meetings, and recently co-authored his first book.  Now he’s working on his second book titled A Lake Manager’s Notebook.  Dick is a Certified Lake Manager and offers lake management consulting services through his business Osgood Consulting LLC.
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