Hangman Creek Water Quality Improvement

Planning Meeting

May 24, 2007

Chair:             Rick Noll, Spokane County Conservation District

Present:          Scott Fields, Coeur D’Alene Tribe

Elaine Snouwaert, Department of Ecology

Reanette Boese, Spokane County

Pat Kane

Gary Ostheller

Layne Merritt, Century West Engineering

Micki Harnois, Town of Rockford

Bill Sayres

Ben Brattebo, Spokane County

Jory Oppenheimir, HDR Engineering

Joe Joy, Ecology

Introductions

The meeting was called to order at 6:35 p.m.  The April 19^th minutes were reviewed.  No corrections were noted.  It was motioned by Micki Harnois to approve the minutes, seconded by Gary Ostheller.  Motion passed.

Public Comment

No Public Comment was given.

Spokane River Dissolved Oxygen TMDL Review

Rick gave a review of the status of the Spokane River TMDL model.  At this time, Ecology is changing how the Spokane River total phosphate load across the border is set for the reference conditions.  The load will now include loadings from the point source dischargers in Idaho.  This will most likely require that the Spokane River TMDL model be re-calibrated. 

Review of WARMF model inputs

Joe Joy with the Department of Ecology updated the model calibration.  There were several changes that improved the model output.  The model calibration corrections incorporated were:

• Improved stream hydrology based on SCCD gaging data.
• Corrected point source operation input at Cheney wetland and Rockford and Fairfield intermittent discharges.
• Improved septic system use estimates.
• Streambank erosion estimations were used across the border in Idaho.

The reference condition (best future condition) was defined as

• No point sources
• Ten foot riparian buffers
• Increased forest cover above Rockford and Tensed
• Limited residential growth in lower watershed
• 60 percent of agriculture in direct seed

Using the new calibration and reference conditions, two scenarios were run and discussed.  The first scenario compared the current total phosphate load at the mouth to what would be expected with the reference conditions.  The second scenario compared the current total phosphate load at the state line with the reference conditions at the state line.  At the mouth, having the watershed land use as listed in the reference condition would reduce the daily average total phosphate load from 103 pounds per day to 82.5 pounds per day.  At the state line, having the upper watershed land use as listed in the reference condition would reduce the daily average total phosphate load from 23.2 pounds per day to 19.0 pounds per day. 

Joe was asked if he could model the above scenarios on a seasonal basis.  Seasonal models will be attempted for the above scenarios.

The other scenarios being modeled are:

• Idaho meets proportional phosphate load at border
• Cheney as existing condition vs. fully discharging to Minnie Creek
• Graduated land use conversions
• Graduated stream bank improvements
• Graduated reforestation
• Graduated direct seed implementation.

NEXT MEETING

The next meeting is scheduled for June 21^st. 

ADJOURN