How is phosphorus getting into lakes and rivers?

Asked by: Jenny Foster

Because phosphorus usually clings to soil particles, the main way in which phosphorus gets into water is when soil is washed in and becomes sediment. Excess phosphorus causes excessive growth of plants in waterways, lakes and estuaries leading to eutrophication.

How does phosphorus get into a river?

Phosphorus moves through the landscape either dissolved in water, or attached to soil particles (particularly fine clays) that are carried along by the water. Soil eroded from the surface of hillslopes, or from the beds and banks of gullies and streams, can also carry phosphorus to streams.

How does phosphorus get into the Great lakes?

Phosphorus reaches rivers and lakes through erosion and leaching from urban areas, farmland runoff, municipal and industrial wastewater discharges, and air pollution.

How does phosphorus runoff into oceans and lakes?

Phosphorus enters the ocean via leaching and runoff, where it becomes dissolved in ocean water or enters marine food webs. Some phosphorus falls to the ocean floor where it becomes sediment. If uplifting occurs, this sediment can return to land.

How does excess phosphorus get into freshwater?

Excess phosphorus enters lakes and ponds from runoff, sewage, and other decomposing matter. Eutrophication in freshwaters has been accelerated by human activities – mainly runoff from fertilized farmland or golf courses and human discharge from wastewater plants.

What causes high phosphate levels in rivers?

Sources of phosphorus in freshwaters



The main sources of phosphorus in rivers and lakes are sewage effluent (primarily from water industry sewage treatment works) and losses from agricultural land. Food waste, food and drink additives and P dosing of drinking waters all contribute to sewage P loadings.

Is phosphorus bad for a lake?

Phosphorus is an essential element for plant life, but when there is too much of it in water, it can speed up eutrophication (a reduction in dissolved oxygen in water bodies caused by an increase of mineral and organic nutrients) of rivers and lakes.

Where does phosphorus come from in lakes?

Phosphorus is a common element in agricultural fertilizers, manure, and organic wastes in sewage and industrial discharges. Rain and snowmelt can wash fertilizers and manure off agricultural land and into ditches, streams, and lakes.

How does phosphorus reach the ocean?

Phosphorus is primarily delivered to the ocean via continental weathering (Figure 2). This P is transported to the ocean primarily in the dissolved and particulate phases via riverine influx.

How do you reduce phosphorus in a lake?

ALUM (aluminum sulfate) is a nontoxic material commonly used in water treatment plants to clarify drinking water. In lakes alum is used to reduce the amount of the nutrient phosphorus in the water.

Is phosphate in water good or bad?

Although phosphate is not harmful to humans, anthropogenic, or man-made, inputs of phosphorus are well known to have a significant impact on ecosystems, and can damage the health of rivers and lakes (known as eutrophication).

Why is phosphate bad in rivers?

Why do phosphates cause a problem? Phosphates are chemical compounds that contain phosphorous. Phosphorous is a key nutrient that both plants and animals use for growth and development. Whilst phosphate is essential for plant and animal life, too much of it can cause a form of water pollution known as eutrophication.

What are phosphorus levels in lakes?

The natural levels of phosphate usually range from 0.005 to 0.05 mg/L. Many bodies of freshwater are currently experiencing increases of phosphorus and nitrogen from outside sources.

How much phosphorus is in Lake Erie?

Excessive algal blooms in the 1960s and 1970s were a major driver for the signing of the first Agreement in 1972. In that first Agreement, the Governments of Canada and the U.S. agreed to reduce phosphorus loads to Lake Erie by more than 50 percent (from 29,000 to 14,600 metric tons per year).

Why are phosphates bad for lakes?

Reducing Nutrients



Too much phosphorus supports rapid algae growth, which can appear as “blooms” of murky scum. Oxygen levels in water decline as the algae decompose. Reduced oxygen kills fish, invertebrates and other aquatic animals.

What should phosphorus levels be in Lake?

Although levels of 0.08 to 0.10 ppm phosphate may trigger periodic blooms, long-term eutrophication will usually be prevented if total phosphorus levels are below 0.5 ppm and 0.05 ppm, respectively.

What is the acceptable level of phosphate in lakes?

0.05 mg/L

To control eutrophication, the USEPA has established a recommended limit of 0.05 mg/L for total phosphates in streams that enter lakes and 0.1 mg/L for total phosphorus in flowing waters (U.S. Environmental Protection Agency, 1986).

Where does phosphorus in lakes come from?

Under normal water flows, roughly two- thirds of the total phosphorus load to lakes and rivers comes from nonpoint sources such as runoff from pasture and croplands, atmospheric deposition and stream bank erosion.

How is phosphorus removed from water?

Chemical treatment for phosphorus removal involves the addition of metal salts to react with soluble phosphate to form solid precipitates that are removed by solids separation processes including clarification and filtration.