Ponds and lakes, whether man-made or not, have a natural life cycle. Before industrialisation began to impact the environment, this progression took hundreds, if not thousands, of years. Today, however, ponds and lakes can be created, grow, and die within just a few decades.

Much of the reason for this lies in the fact that water is one of our most (ab)used and least understood natural resources; we allow ponds and lakes to go unmanaged and, before long, they become unmanageable.

We don’t need to remind ourselves of the challenges we face in terms of the volumes and quality of the water we use; areas that we once believed to be immune from shortages are now at risk. As such, more and more people are turning towards alternative resources like recycled water and sustainable water management methods.

Sustainable irrigation and the benefits of recycled water

Recycled water has the advantage of being located close to places of use, available in large quantities throughout the year, and rich in useful nutrients. 

In the case of recycled water, large quantities can be utilised for plants and crops, as well as irrigated agriculture and green spaces. Recycled water is, therefore, becoming an essential part of sustainable irrigation and, more broadly, lake and pond management.

If not properly and proactively managed, any lake or pond used as a reservoir will likely see its water quality quickly deteriorate into a eutrophic condition.

Did you know? Eutrophication describes when a body of water becomes overly enriched with minerals and nutrients, inducing excessive growth of algae and subsequent oxygen depletion of the water body.

How to successfully manage ponds and lakes: your guide to a healthy water body

Successful pond and lake management begins with a basic understanding of how three mechanisms operate in a pond or lake, affecting its overall condition. Unsure what they are? Keep reading, we’ll cover how you can keep your pond or lake clean and healthy.

1. Monitor thermal stratification

Temperature layering, or thermal stratification, occurs when the sun warms the surface water, causing it to become less dense. 

As the warming process progresses, the water becomes separated (stratified) into layers. Colder water settles on the bottom and water gradually gets warmer closer to the surface. Because the surface layer remains warm, algae growth thrives, so by monitoring thermal stratification, you’re monitoring the health of your water.

2. Keep an eye on nutrient levels

Like any living body, ponds accumulate and digest organic matter. Organic nutrients containing phosphorus and nitrogen are essential for pond plant life, but you must keep the nutrient level balanced to avoid severe weed and plant growth. 

A pond may become eutrophic due to run off from nearby turf areas, leaching fertilisers, or from domestic septic systems, leaves, grass clippings, or other organic waste. In addition, when the algae and aquatic weeds living in the pond die, they will further increase nutrient levels. 

As these levels rise, the rate of plant growth will also increase, initiating the gradual consumption of the pond by organic sludge.

3. Pay attention to oxygen depletion

The third and final mechanism that affects a pond, and therefore how it’s managed, is oxygen. Oxygen is used by the pond to clean itself of excess nutrients with aerobic bacteria. 

In oxygen depleted ponds, phosphorus, ammonium (a nitrogen compound), and some metals become increasingly soluble and are released from its sediment. Mixing the water up – whether via cold fronts, winds, or cold rains – transports some of these nutrients to the surface, where they stimulate algae production.

As a pond ages and nutrient levels rise, algae and aquatic plant life increases. Naturally, these plants will die, sink to the bottom of the pond, and begin to decompose, causing a biomass problem.

Did you know? Biomass refers to the organic material that comes from plants and animals. When a water body has excess, nutrient-rich biomass, it can increase algae and plant production.

However, due to thermal stratification, upper and lower layers of water do not mix, and therefore the oxygen needed to support pond life doesn’t reach the bottom of the pond. Oxygen depletion in lower layers of the pond can mean dead fish, foul odour, stagnant water, and other aquatic problems.

Problem solving with water management techniques

Answering your frequently asked questions

There are several methods available to help solve some of the problems ponds and lakes are subject to, and we find there are several popular FAQs pertaining to the water management techniques that resolve them. Here are five of the most common:

How do I remove algae and aquatic plants?

Mechanical control can be used to remove algae, aquatic plants, and their root systems. This is best facilitated in medium to large ponds and would be achieved by dredging, weed harvesting, roto-tilling, or raking. 

However, this is a temporary solution because it treats the symptoms rather than the cause. Also, it is relatively expensive, labour intensive, and will need to be repeated as the plants regenerate.

Can I use chemicals to manage ponds and lakes?

Chemical control is the most common method of pond and lake management. Herbicides are applied to the pond to kill the algae and plants. 

This is quick and effective but may, in the process, kill fish and cause bad odours. In addition, chemical control, like mechanical control, treats symptoms of the problem; it’s expensive, often requires permits, and may damage surrounding turf and plants if the treated water is used to irrigate other areas.

Is biological control an effective pond management strategy?

Biological control is an effective method of pond management. One application is the introduction of weed-eating fish, like koi or grass carp. These can be quite effective in keeping excessive weed growth under control. They are inexpensive over the long term and require no labour or upkeep once they are in the water. They are hearty feeders, but will consume algae only if their preferred aquatic plants are not available. Plants utilise photosynthesis in the pond to create dissolved oxygen, so if all the aquatic plant growth in the pond and a major source of oxygen is removed, this can result in odour and water quality problems.

A second biological control method is the introduction of wetlands at the areas where water or runoff flows into the pond. First, this will slow the progress of water into the pond, reducing erosion and flooding problems. Secondly, the intensive plant growth in a wetland area acts as a nutrient sink for high-nutrient water flowing into the pond. By absorbing nutrients before they enter the pond, wetland plants actually improve water quality due to lower organic nutrient levels, if a balance can be found. 

What are the benefits of lake dye?

Lake dye can be effective in improving the appearance of a pond or lake. It blocks penetration of sunlight into the pond, subsequently slowing the growth of aquatic plants, and creating a dark blue hue.

Why should I invest in aeration equipment for my pond or lake?

Finally, aeration is the most effective, long-term pond and lake management tool and can be used in conjunction with any of the aforementioned treatments. 

If natural aeration isn’t working, then mechanical aeration is the option. 

Aeration, by definition, is the mechanical addition of oxygen to the water. 

By depositing large amounts of oxygen into the water, aeration encourages strong aerobic bacteria to clean the pond of organic nutrients and waste. High oxygen levels also prevent anaerobic digestion that leads to nutrient cycling and foul odours. 

The circulation rate produced by aeration breaks through the thermal stratification and distributes oxygen to all parts of the pond. By pulling cooler water to the surface of the pond, algae growth is slowed and the water’s pH level is balanced, which reduces odours. 

Aeration is economical, supports the natural ecosystem, and most importantly, attacks the source of the problem continuously.

Work with us on your water management protocols

By taking a proactive approach to water quality management you can help ensure your water features are clean, functional, and aesthetically appealing for years to come.

For more detailed pond and lake management information, contact Reesink Hydro-Scapes on 01480 226800 or email [email protected].