July 7, 214 Subject: Proposal to limit Namakan Lake to 197 Upper Rule Curve for remainder of summer Background: Flooding in 214 has resulted in the highest water levels on Namakan Lake since 1968, and the highest on Rainy Lake since 195. Damage has occurred along both lakes to private properties as well as to tourist businesses and community infrastructure. The reports of greatest damage in the Namakan Lake basin are upstream in the area of Crane Lake/ Sand Point Lake, where the level has been several inches higher than at Namakan/ Kabetogema. Namakan Lake peaked on June 18 at 341.55 m, 6 cm (24 in) above the URC, and 45 cm (18 in) above the All Gates Open Level. Crane Lake peaked at 341.68 m on June 18. Since peaking, the main gauges on Namakan/ Kabetogema and Crane Lake have followed a general decline. The rate of decline over the past week has been nearly steady at 2 cm/ week (8 in/ week). Rainy Lake appears to have reached a peak over the past week, as tributary flows continue to drop. Some rainfall over the weekend has prevented a substantial rate of decline, and more rain is in the forecast this week. The level of Rainy Lake is 97 cm (38 in) above the URC, and 81 cm (32 in) above the All Gates Open Level. With the adoption of the 2 Rule Curve, Namakan Lake is drawn down over the summer period to more closely resemble at natural system. The 2 Upper Rule Curve (URC) begins declining on June 1 at the 197 URC Level. Whereas the 197 URC stays constant at 34.95 m (1118.6 ft) through to October 1, the 2 URC declines from 34.95 m (1118.6 ft) to 34.65 m (1117.62 ft) by September 1, a drop of 3 cm (12 in). Some interests, principally tourist operators, around Rainy Lake have requested that Namakan Lake be held to its 197 Upper Rule Curve once it declines to that level. They maintain that the level is suitable for business interests around the lakes, as lower levels impede navigation in the late summer. To evaluate the effect that holding the lake at the 197 URC would have on Namakan Lake outflow and the levels of Namakan and Rainy Lake, a simple analysis was undertaken by the Lake of the Woods Secretariat. Details of Analysis: 1. The analysis compares two alternatives. Alternative A is for an IJC Order to hold at the 197 URC until the end of August. Alternative B is to allow the lake to decline along the 2 URC through the summer (NOTE: not declining into the middle of the Rule Curve range). 2. The analysis computes the outflow difference necessary to carry out Alternative A versus Alternative B.
3. The analysis also determines the effect of this outflow difference on the level of Rainy Lake. 4. The analysis begins on the date that the level of Namakan Lake is expected to reach the 197 URC level, July 13. 5. Without a log operation, Namakan Lake is assumed to continue to decline at the current rate until the summer 2 URC level is reached. This is expected to occur July 19. 6. It is assumed that inflow will continue to decline for Namakan Lake into the normal range over the course of the summer. Significant increases in inflow, beyond the outflow capacity, negate this analysis. 7. All levels are relative to the main Namakan/ Kabetogema level gauges, Crane Lake and other upper lakes will be higher and aren t included in the analysis. Results From July 13-July 18 (corresponding to the level reaching the 197 URC and declining to the 2 URC) the outflow reduction required to hold the 197 URC under Alternative A, is 8 m³/s. Over the course of this 6-day period, the additional level benefit for Rainy Lake is 4.2 cm (1.6 in). From July 19- August 31, since Namakan Lake under Alternative B follows the steady decline of the 2 URC, there is a constant reduction of 9.4 m³/s required out of Namakan Lake to hold the 197 URC of Alternative A. Reducing outflow from Namakan Lake from July 19-August 31 by 9.4 m³/s results in a benefit to Rainy Lake of 3.7 cm (1.45 in). The total benefit for Rainy Lake for the period July 13-August 31 is estimated to be 8. cm (3.1 in) by following Alternative A As a result if Alternative A, Namakan Lake would be 3 cm (12 in) higher on August 31 that in Alternative B.
Namakan Lake Upper Rule Curve Comparison 341 34.95 34.9 34.85 34.8 34.75 34.7 34.65 2 Upper Rule Curve 197 Upper Rule Curve Projected Level to Track 2 Upper Rule Curve 34.6 34.55 34.5 13.Jul 2.Jul 27.Jul 3.Aug 1.Aug 17.Aug 24.Aug 31.Aug 9. Namakan Outflow Reduction & Associated Rainy Lake Decline.8 Namakn Outflow Reduction (m³/s) 8. 7. 6. 5. 4. 3. 2. 1. Namakan Flow Reduction to hold at 197 URC Rainy Lake Daily Level Decline Due to Holding at 197 RC.7.6.5.4.3.2.1 Rainy Lake Drawdown Achieved by Namkan Flow Reduction (cm). 13.Jul 2.Jul 27.Jul 3.Aug 1.Aug 17.Aug 24.Aug
Considerations The benefit for Rainy Lake is not very significant over the period in question in relation to the rate of drawdown likely in late summer. Normal precipitation and warmer summer conditions could very well see Rainy Lake begin declining quickly so that the timing of returning below the All Gates Open level will not be affected by more than a day or two by adopting Alternative A. The effect on the timing of returning to the Rule Curve band is even smaller, as it is likely that the Water Levels Committee would prefer to see a more gradual reduction in Rainy Lake outflows as the level approaches the band for the benefit of Rainy River. A decision to hold Namakan at the 197 Upper Rule Curve would be potentially detrimental to ecological interests that benefit from a more natural seasonal decline. It does not appear that this level is problematic for navigation or property interests. In June of 22, following the 49 th Parallel storm, Rainy Lake had reached a very high level, but Namakan Lake outflow was sufficient to keep the level slightly above the URC. The IJC issued an Emergency Order giving the IRLBC the authority to limit the outflows from Namakan Lake while Rainy Lake remained significantly in excess of its IJC upper emergency level, taking into account conditions on Namakan Lake and upstream, on Rainy Lake and downstream, and at the Boise powerhouse. The IRLBC directed the Companies to raise the level of Namakan Lake by 13 cm (5 in) to the All Gates Open level (though there were calls to raise it higher) to provide relief to Rainy Lake,. This was done under a favourable 5-7 day forecast and declining inflows entering July. On July 4-5, a significant rain event occurred sending Namakan Lake up 12 cm (4.7 in) in two days. This left the IRLBC in a difficult position as it wanted to abate the rate of Namakan rise without exacerbating the flooding on Rainy Lake. It is important to note that the inflow to Namakan Lake through this period was less than upper quartile (near 275 m³/s) there was room to manoeuvre up or down as the outlet of Namakan Lake was not near outflow capacity. Today, inflow to Namakan Lake is at 55 m³/s, greater than 95 th percentile, with maximum outflow capacity at 6 m³/s. Both the inflow and the outflow from the fully opened Namakan dams are in a steady, gradual decline which has allowed Namakan Lake to decline. But the differential is not changing appreciably. Until inflow returns to the normal range there will not be much room to increase outflow in response to a significant rain event, making storage much more important. The risk of further flooding on Namakan is greatly diminished if inflow falls quickly and the flow difference between Alternative A and Alternative B is the difference of a couple of logs out of many already in. At the recent rate of decline, Namakan Lake inflow may fall below 9 th percentile by the end of July.
LWCB Lake of the Woods Control Board 339. 338.8 RAINY LAKE IJC 2 Rule Curves IJC 2 Drought Line IJC All Gates Open Bear Pass Fort Frances 213 214 SEP OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG ISSUED: 214.7.7 * Provisional Data * 1112 338.6 1111 338.4 111 338.2 338. 119 ELEVATION (m) 337.8 337.6 118 ELEVATION (ft) 337.4 117 337.2 337. 116 336.8 115 336.6 336.4 114 NET INFLOW (m³/s) 18 16 14 12 1 8 6 4 2 6 55 5 45 4 35 3 25 2 15 1 5 NET INFLOW (ft³/s) 12 4 1 35 OUTFLOW (m³/s) 8 6 4 3 25 2 15 OUTFLOW (ft³/s) 2 1 5 SEP OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG
LWCB Lake of the Woods Control Board 341.8 341.6 NAMAKAN LAKE IJC 2 Rule Curves IJC 2 Drought Line Crane L Gold Portage Kettle Falls 213 214 SEP OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG ISSUED: 214.7.7 * Provisional Data * 1121 341.4 341.2 341. IJC All Gates Open 112 1119 34.8 1118 34.6 ELEVATION (m) 34.4 34.2 34. 339.8 1117 1116 1115 ELEVATION (ft) 339.6 1114 339.4 339.2 1113 339. 338.8 1112 338.6 1111 338.4 9 8 3 7 25 NET INFLOW (m³/s) 6 5 4 3 2 15 1 NET INFLOW (ft³/s) 2 1 5 8 7 25 OUTFLOW (m³/s) 6 5 4 3 2 15 1 OUTFLOW (ft³/s) 2 1 5 SEP OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG
LWCB Lake of the Woods Control Board 341.8 341.6 NAMAKAN LAKE IJC 2 Rule Curves IJC 2 Drought Line Crane L Gold Portage 22 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC ISSUED: 214.7.7 * Provisional Data * 1121 341.4 341.2 341. IJC All Gates Open 112 1119 34.8 1118 34.6 ELEVATION (m) 34.4 34.2 34. 339.8 1117 1116 1115 ELEVATION (ft) 339.6 1114 339.4 339.2 1113 339. 338.8 1112 338.6 1111 338.4 9 8 3 7 25 NET INFLOW (m³/s) 6 5 4 3 2 15 1 NET INFLOW (ft³/s) 2 1 5 8 7 25 OUTFLOW (m³/s) 6 5 4 3 2 15 1 OUTFLOW (ft³/s) 2 1 5 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
LWCB Lake of the Woods Control Board 339. 338.8 RAINY LAKE IJC 2 Rule Curves IJC 2 Drought Line IJC All Gates Open Bear Pass Fort Frances 22 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC ISSUED: 214.7.7 * Provisional Data * 1112 338.6 1111 338.4 111 338.2 338. 119 ELEVATION (m) 337.8 337.6 118 ELEVATION (ft) 337.4 117 337.2 337. 116 336.8 115 336.6 336.4 114 NET INFLOW (m³/s) 18 16 14 12 1 8 6 4 2 6 55 5 45 4 35 3 25 2 15 1 5 NET INFLOW (ft³/s) 12 4 1 35 OUTFLOW (m³/s) 8 6 4 3 25 2 15 OUTFLOW (ft³/s) 2 1 5 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC