Tyler Yasenak, Green Bay Ecological Services Office biologist , takes flow measurements in the Lower Fox River, during the sturgeon spawning season. The flows shown here are preferred for successful sturgeon reproduction and are now a required objective of a new Sturgeon Protection Plan that regulates hydroelectric production at this dam. - FWS photo by Rob Elliott

The use of water for hydropower production in the Lower Fox River can result in the dewatering of habitat used by sturgeon for reproduction when flow conditions are low. A new Sturgeon Protection Plan helps prevent this during the sturgeon reproduction season. - FWS photo by Rob Elliott

Lake sturgeon migrate out of Green Bay up into the Lower Fox River to spawn every spring. Though few in number, the 25-75 fish that spawn each year represent the 3rd largest of eight known spawning populations remaining in the Lake Michigan basin. - FWS photo by Rob Elliott

After several years of ongoing discussion and negotiation, coupled with continued data collection and analysis by Fish and Wildlife Service personnel, a plan for the protection of lake sturgeon below the De Pere dam was agreed to. 

The agreement was made by representatives from the Service’s Green Bay Fisheries Office and Green Bay Ecological Services Office, the Wisconsin DNR, the US Army Corps of Engineers, and Thilmany Papers Nicolete Mill which hold a FERC license for hydroelectric generation at this site.

The “Protection Plan” was a requirement the Fish and Wildlife Service had requested as a condition of a new FERC license being issued to the Nicolet Mill for continued hydroelectric generation.  The Plan describes the manner in which the agencies and company will work together into the future to ensure that adequate flow conditions for successful sturgeon reproduction are maintained below the De Pere dam. 

Rob Elliott and Tyler Yasenak from the Green Bay Fisheries Office and Ecological Services Office respectively, along with the office’s supervisors Mark Holey and Louise Clemency, have all been involved in negotiating the details of this plan from the initial stages of convincing FERC that this protection plan was needed, through periods of drafting multiple official comments on initial draft plans submitted by the power company, to finally working together with Nicolet Mill staff and representatives from the other agencies to produce a final plan that all could agree to. 

Over the last 3 years, observations of sturgeon spawning and reproduction were documented and historical data were analyzed to determine what sort of minimum flow requirements were necessary for successful sturgeon reproduction at this location. 

Then various scenarios were laid out and evaluated to determine what procedures could be employed that would ensure adequate flow with the least restrictions to power production at the Mill.  The final protection plan now specifies a minimum water elevation in the pool above the dam which, when combined with the use of flashboards, directs adequate flow of water over the target habitat. 

When river flows are not adequate to provide both this minimum flow and full power generation, then the Nicolet Mill will decrease hydroelectric generation as needed to maintain the minimum pool elevation and thus direct the necessary minimum flow over the spawning habitat.  Unless otherwise determined each year, this minimum flow will be maintained from April 15 – June 15. 

Integral to the agreement are plans by the Army Corps to install a real-time pool elevation meter that can be monitored on-line by all parties.  Also, the agencies and the Mill have agreed to work together to monitor the annual use and timing of sturgeon spawning below the dam so that accurate projections of the duration of the incubation period can be made each year with the expectation that flow may not always be required for the full 2 month period if spawning and incubation are completed prior to June 15. 

Potential improvements to the plan and details of implementation will be determined at a coordination meeting of all parties in February of each year.  Regular communication among all parties will then continue during the spawning and incubation period each season to ensure that the flow needs for successful sturgeon reproduction are met.

The protection of this habitat for sturgeon reproduction now opens the door for increasing the sturgeon population in the Lower Fox River.  Prior to this plan, the only habitat used by spawning sturgeon in the Lower Fox River frequently became dewatered during the egg and larval incubation period (as is shown in the accompanying photographs), reducing survival of incubating eggs and larvae.  Though the 25-75 adult sturgeon that currently return to spawn in this river are few compared to the thousands that historically spawned at this site, their abundance ranks 3^rd of 8 known remnant populations persisting in Lake Michigan, and they might be capable of supporting  a natural population recovery given suitable environmental conditions.  The implementation of this protection plan now opens the door to expanding other rehabilitation efforts for sturgeon in this important Lake Michigan tributary.

Contact: Rob Elliott, USFWS, Green Bay NFWCO, robert_elliott@fws.gov, or Tyler Yasenak, USFWS, Green Bay ESO, tyler_yasenak@fws.gov.