ARCHIVE

Tons of trouble: Erosion causes sediment to pile up in reservoir

Staff reporter

Think about this.

In a 120-day period, the equivalence of four acres, six inches deep was washed into French Creek Cove at Marion Reservoir.

That sediment was comprised of 4,400 tons of dirt, phosphorus, nitrogen, nutrients, and other materials found in soil.

Those stunning statistics were revealed July 24 to approximately 40 county and city officials who were part of a tour of Marion County conservation projects conducted by Gary Schuler of Natural Resources Conservation Services, Marion, and Peggy Blackman, director of WRAPS (Watershed Restoration and Protection Strategy).

Dr. Philip Barnes is a research engineer with department of biological and agricultural engineering, K-State Research and Extension and was the bearer of the news.

This significant erosion was caused by two major events.

Two sizable rainfalls occurred in May, producing 12 inches of rain. Typical rainfall in May is five inches.

With the erosion and sediments streaming into the lake, the water became polluted and farmers lost nutrients from their fields.

Best management practices can reduce and even prevent this type of erosion from occurring.

"We need to keep sediments out of the lake," Barnes said. "If we don't, we could have an algae outbreak like before."

Barnes was referring to the summer of 2004, when a wide-spread bloom at the reservoir caused concern.

Blue-green algae forms when lake water is clear and the sunlight is able to penetrate through the water. With high nutrient levels, especially phosphorus, blooms can occur. Toxins are not released until the bloom dies which reduces oxygen levels in the water, and causes stress and even death to aquatic life, especially fish.

Barnes was most impressed with the amount of sediments and nutrients lost in the lake which was more than in other individual lakes.

Five thousand dams have been built in Kansas in an effort to slow down erosion. Barnes said the dams are effective in trapping sediments but they block minnows and other species of fish.

Barnes told the group about growing issues with Tuttle Creek Reservoir and Milford Reservoir which are the main water sources for Topeka and the major Kansas City areas.

"There are 800,000 people currently living in the corridor between Manhattan and Kansas City," Barnes said. In the coming years, the population is expected to explode to 3.5 million.

"Sediment could cause low water availability," he said.

These issues were not new to the group as Marion Reservoir also is faced with a similar situation of sediment filling the reservoir bowl.

Barnes said it could cost $80 million to dredge Tuttle Creek, which is not practical.

Conservation practices are needed to avoid costly solutions like dredging.

On a local level, Barnes said KSU will continue to monitor the effects BMPs and erosion have on the reservoir. Grant funds will be pursued to be used within Marion County.

Barnes also said that Kansas Department of Wildlife and Parks was using the reservoir as a pilot program to try and reduce the amount of the potentially dangerous blue-green algae by increasing plant life.

Phytoplankton is a type of algae that lives in the reservoir and actually eats the blue-green algae.

KWP will remove carp and buffalo fish by seining or netting and selling to commercial fishermen, Barnes said.

"Getting rid of the carp and buffalo fish will help the plankton population," he said.

Costly calamity

The erosion that lands in the lake, some due to poor conservation practices, is more than dirt.

In that 8,800,000 pounds of dirt that the research team measured, there were 48 tons of nitrogen and 15 tons of phosphorus.

At Cooperative Grain & Supply, nitrogen is sold in dry, liquid, or gaseous forms. Typically, it is priced by the pound.

According to Kevin Suderman, certified crop adviser with the co-op, if a producer applies 50 pounds of total product, he has applied 41 pounds of actual nitrogen.

Phosphorus also is sold in liquid and dry formulations but not in gaseous states. Typically phosphates come with some form of nitrogen but the process by which they are produced determines the level, Suderman said. Phosphates also are sold by the pound.

Costs vary during the year but nitrogen in the past 12 months has ranged from 30 cents to 50 cents per pound of nutrient. Phosphates have been more steady at 42 to 53 cents per pound of nutrient, Suderman said.

"The approximate application of nutrients changes from crop to crop but wheat, corn, and milo are similar in usage," Suderman said.

Thin soils would generally require less nutrients because of a decreased change of production.

For an 80-bushel milo crop, a producer would generally apply 96 pounds of nitrogen and 30 pounds of phosphate which would cost, at today's prices, $53.50 per acre in the dry formula.

A more aggressive approach is taken when the land is more productive along rivers and streams as yields can reach well over 100 bushels per acre for corn or milo.

Quantcast