20 January 2012

Mowing Carter Lake Waters Like a Lawn

Once aquatic vegetation growth gets going this spring, officials plan to mow submerged plants in the water like a lawn.

This was one portion of the effort to improve water quality and fisheries for the Carter Lake project, as presented at a January 19th information meeting, held at MAPA offices in north Omaha.

Three speakers provided comments to a crowd of about fifty interested people, along with about a dozen officials.

There will be a "more aggressive plan this year" to remove vegetation from the lake, said Chris Larson, a fisheries biologist with the Iowa Department of Natural Resources. He presented information on a vegetative management plan. Following alum treatments and removal on rough fish, "incredibly clear water" resulted in an abundant growth of aquatic vegetation.

The plants were not welcomed by boaters and water-skiers, with this point-of-view apparent at the Thursday evening meeting.

Mechanical, chemical and biological options to inhibit vegetative growth were presented by Larson.

"Liken it to mowing a lawn," said Larson, while presenting options for mechanical removal. The effort would start in late April or early May, and continue throughout the growing season.

Answers to some basic questions were not available at the meeting. An inquiry to three officials was focused upon:

* What are the actual dates when mechanical clearing would occur?
* What areas would be the focus for mechanical clearing efforts?
* What are the expected costs of the mechanical clearing effort?
* Who would pay for the mechanical clearing?
* How would mechanical clearing impact other known uses of the lake waters?

Plant harvesting would likely commence in late April or early May and continue fulltime through the growing season, Larson said.

At least $30,000 was spent for this effort during eight weeks in July-August 2011, according to Larson's presentation. This cost did not include the funds provided by the city of Omaha and Carter Lake to pay someone to operate the equipment.

Larson said a plan indicating specifics of mechanical clearing efforts might be available in early March. There will be attention given to the main lake and boating area, especially where there is a 4-8' water depth.

Though no cost estimates were available, based upon an approximate calculation, it would require about $4000 per week the expense of clearing vegetation. One option mentioned was the purchase of mechanical clearing equipment for ca. $170,000. It could then be used each year.

While listening to comments on the "so-called problem" with vegetation, one project proponent was overhead saying "we need to do whatever we can and if that doesn't work, try something else."

Chemical options are also being actively considered. There is a requirement for a permit, according to Iowa regulations. Most of the lake waters are in Nebraska.

Iowa would prefer a single permit to cover all areas of potential application. One permit would be issued to the City of Carter Lake to allow all applications.

A graphic shown during his presentation showed an ungiven number of linear feet of lake bank — especially in the Carter Lake urban area — where chemicals could be applied by a licensed applicator.

Officials in a Des Moines regulatory office are already agreeable to such a permit request, Larson said.

There would be only a few sites where chemical control of plants would occur on the Nebraska portion of the lake. The presenter suggested that the Iowa permit could also be used for these places within Levi Carter Park.

An application of chemicals costs about $200 per acre, according to figures given at the meeting.

Biological applications were a third option.

Suitable plants could be established, with a particular indication of the value of water-lilys. A primary area of water dredging in the east arm of the lake will exclude the known water-lily wetland.

The use of grass carp is not allowed in Iowa waters. The legality of their introduction into Nebraska waters was not presented.

Earlier in the meeting comments were given about what has already been done and what will happen in the coming months, associated with the project.

In the next eight months, project facets include, as presented by a representative of TetraTech:

  • shoreline stabilization using earth and rock fill
  • construction of groins that will be 25' long and 25' wide; they will have an earth core stabilized by rock
  • construction of offshore breakwaters
  • construction of perpendicular breakwaters that will be 30 feet long and placed into the lake, with a top elevation one foot above the normal water elevation
  • dredging to increase water depth in some places of the east arm of the lake, with some dredged material dumped into the lake near the island, to reduce lake depth; 50,000 cubic yards will be removed based upon the removal of 2-3 feet of the lake bottom
  • building a wet detention basin
  • impeding runoff through the Levi Carter Pond by dumping rock to create barriers and by promooting vegetative growth; this particular site was mentioned as not having; this water area was "not reaching the efficiency it could" to provide a reduction of pollutants from adjacent urban runoff, according to the speaker from TetraTech.

Project items already completed were given by Brad Richardson, project coordinator, at the start of the 35 minutes of given presentations. They were:

  • alum treatment;
  • fisheries renovation;
  • watercraft management, including buoy management and marking of a no-wake zone;
  • construction of bioretention and bioswale areas on the southern shore of the lake, within urban Carter Lake;
  • meeting water quality goals; and,
  • publication of a "success story" by the Environmental Protection Agency.

A bid of $2,637,426.12 was approved December 6th, 2011 by the Omaha City Council. Western Construction Corporation will be the primary contractor, who will:

"furnish labor and materials to install water quality improvements, including shoreline stabilization, dredging and construction of a water quality basin at Carter Lake in Omaha, Nebraska and Carter Lake, Iowa." ... "Funds in this amount shall be paid from the 2006 Parks and Recreation Bond Fund No. 13354 and Organization No. 117315, 2010 Issue Parks and Cultures Bond."

At this council meeting, there was also a hearing on an appeal by K&L Construction Inc. on the rejection of their October 26, 2011 bid submitted for the Carter Lake Water Quality Improvements project. Their appeal was denied in a 7-0 vote.

Project construction will start Monday, January 23rd. It will begin at the south end of the west arm, and continue clockwise around the lake. During construction, portions of park roadway and the recreational path will be temporarily closed.

Work included in the approved bid, does not include any additional steps associated with vegetative management, including mechanical clearing and chemical spraying.