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To reduce runoff, Vernon County multi-hazard mitigation plan emphasizes land use

To reduce runoff, Vernon County multi-hazard mitigation plan emphasizes land use

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POSTED January 9, 2019 4:25 p.m.

VERNON COUNTY - In the Multi-Hazard Mitigation Plan approved by the Vernon County Board of Supervisors at their December meeting, addressing land use as a major contributor to flooding and dam failures was featured prominently. 

Land use projects included in the report were proposed by Vernon County Conservationist Ben Wojahn and members of the Emergency Management and Zoning departments at a public input meeting held in November in Viroqua.

In the current final draft of the Crawford County plan, like Vernon County’s prepared by the Mississippi River Regional Planning Commission (MRRPC), little mention is made of land use as a contributor to the county’s flooding hazard. In the Crawford County Multi-Hazard Mitigation Plan, projects involving land use are confined to enforcement of floodplain and wetland zoning ordinances, buyouts of properties in the floodplain, and pursuing expansion of conservation easements.

Vernon plan

The Vernon County plan has a number of concrete proposals for taking land use into consideration in the preparation for flooding hazard mitigation in the county. Most of the proposals added to the plan were proposed by Vernon County Conservationist Ben Wojahn, and approved by the Emergency Management Committee for inclusion in the final version of the plan.

“I made the proposals that I did because I believe that our county needs to do whatever we can to slow down the volume and velocity of storm water entering our watersheds in the increasingly large rain events our area has seen in recent years,” Wojahn said. “We need to put a laser focus on where the county and private landowners can best install conservation practices that increase water infiltration and slow water down before it enters the watershed or contributes to stress on our flood control structures.”

Projects proposed by the Vernon Land Conservation (LCD), Emergency Management and Zoning (EMZ) Departments, and approved in the final plan, include:

• consider developing a county driveway ordinance that requires new driveways and access roads to be operable for large or emergency equipment during flood events (EMZ)

• create a new position within the LCD for the purpose of mapping and documenting current and historical flood damages, and for designing flood mitigation, water retention and conservation practices (LCD)

• develop mapping and model flood mitigation priorities (LCD)

• use modeling, including EVAAL, to identify priority areas for conservation and mitigation practices and projects (LCD)

• develop a strategy for changed practices (sizing, lowering roads, etc) (LCD)

• develop a landowner/farmer outreach program which will increase the number of practices that will retain water (LCD)

• develop a cost-share program for flood mitigation projects (LCD)

• update high water warning system (LCD)

• develop a procedure for prioritizing voluntary buyouts (LCD)

• conduct a cost-benefit analysis of best management projects, which could include smaller dam structures, berms, swales, terraces, prairie buffers and other practices to retain water on the landscape (LCD)

• create a watershed-based engineering position to assist technicians (could be multi-county) (LCD)

• conduct a feasibility assessment on the development of cost-sharing program of rain gardens and other storm water retention practices (LCD)

Dam failure hazard

Crawford County has only one large earthen PL-566 flood control structure. The Blackhawk-Kickapoo Dam is located on Johnstown Road in Utica Township. It dams the Nederlo Creek, a tributary of Tainter Creek.

Crawford County has given ‘dam failure,’ a hazard rating of ‘low,’ with a numeric score of ‘8.’ Similar to Crawford, Vernon County has also given ‘dam failure’ a hazard rating of ‘low,’ with a numeric rating of ‘9.’

Given recent historic flooding compounded by dam failures in the headwaters of the West Fork of the Kickapoo River, one might be puzzled by the hazard ratings both counties have given the dam failure hazard.

There is widespread consensus that our area has seen increasingly frequent large rain events that exceed the old ‘100-year frequency’ standard. The rain events strike with unpredictability so that different areas can take the brunt of a catastrophic rain event.

Gays Mills was particularly impacted by a large rain event in 2007 that caused dangerous flash flooding in the early morning hours in the village, when most residents were asleep.

Rural Utica Township residents Al Slavik and Shirley Northern live and raise grassfed beef in the valley below the Blackhawk-Kickapoo Dam.

“The only time we were worried was in 2007, when the water filled up the impoundment to the top,” Slavik said. “We walked up to look at it, and began to get a little worried. Should we start moving things to higher ground? Evacuate?”

As we saw in the breach of the Jersey Valley and Mlsna Dams in the 2018 Labor Day flood events, it was not the dams themselves that gave way, but rather the hillside near the auxiliary floodwater spillway that eroded and breached.

Assessment of the Blackhawk-Kickapoo Dam could be viewed as an important initiative. The Crawford County plan lays out the county’s plan in the event of a breach:

 “Emergency Action Plan on Nederlo Creek: This warning plan is in effect to safeguard lives and reduce property damage to citizens who live below a zoned earth embankment dam called Blackhawk-Kickapoo structure on Nederlo Creek. This dam was constructed in 1975 for the purpose of flood control…There is one residence in the floodplain shadow. An Emergency Action Plan for this dam has been prepared in the event that the dam breaches. This involves a chain of communication from first observance of a breach to the notification of downstream residents by way of the county conservation coordinator and sheriff’s office.”

The reality is, that the dam did what it was supposed to in 2007 and held back water that would potentially have made the catastrophic flash flooding in Gays Mills even more dangerous. The dam, when full, holds 68,975,013 gallons of water. Given what happened in Vernon County recently, are Crawford County residents satisfied that the dam and the hillside to which it is anchored are adequately engineered to hold in the kinds of catastrophic rain events that we’ve increasingly seen in our area?

Public input meeting

Crawford County’s Public Safety and Land Conservation Planning and Zoning Committee will hold a public information meeting on the Crawford County All Hazards Mitigation Plan on Thursday, Jan. 17, at 5 p.m., at the Crawford County Highway Department located at 21515 Highway 27 in Seneca.  

The purpose of this public hearing is to receive public input on the County’s All Hazard Mitigation Plan that is being updated in accordance with the Federal Disaster Mitigation Act of 2000.  By updating this five-year plan, the county, towns, villages and cities will remain eligible for FEMA’s hazard mitigation grant programs. 

This will be county resident’s last chance to have input into the plan before it is sent to the Crawford County Board of Supervisors for approval at their February 2019 meeting. 

Prior to the public comments, a brief presentation will be made on the process used to update the plan, hazard risk assessment research that was conducted, and on some projects that have been identified to reduce future damages and losses from hazards.  

For those individuals who cannot attend this meeting and want to provide written comments, please submit them by January 17, to Jim Hackett, Emergency Management, Crawford County, 224 N Beaumont Rd. Prairie du Chien, WI 53821.

For those who would like to view the plan online, it is available at ww.crawfordcountywi.org/land-conservation-home.html

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