Des Moines River Water Quality Network

Transcription

1 Des Moines River Water Quality Network Monthly Report for December 2014 Donna S Lutz Assistant Scientist/Project Manager 394 Town Eng Bldg Iowa State University (515) dslutz@iastate.edu 01/20/15 T:\CCEE\Private\lutz share\files\saylrr\word\monthly\template_title.doc

2 Des Moines River Water Quality Network Introduction Monthly Report for December 2014 There was one sampling event in December (December 8). The sampling day inflows into Saylorville Reservoir and Red Rock Reservoirs were 1,070 ft 3 /s and 3,476 ft 3 /s, respectively, which were near normal. The project's long-term ( ) December average sampling day flow at Station 1 was 1,295 ft 3 /s and the long-term ( ) December average sampling day flow at Station 7 was 3,453 ft 3 /s. Observations Between sampling events (November 3 December 8) there had been only 0.58 inch of precipitation. November and early December were much cooler than normal with lower precipitation. The reservoirs were partially ice covered on December 8 and therefore boat access was not possible. Values of ph were fairly consistent with ph ranging from 8.04 to The average total hardness concentration at the sampled riverine stations was 393 mg/l as CaCO 3 this month, as compared to 374 mg/l as CaCO 3 at these sites in November. Last December, the total hardness concentration at the riverine stations averaged 362 mg/l as CaCO 3. Turbidity and suspended solids concentrations were low. Turbidity ranged from 4 to 12 NTU on the Des Moines River and was 11 NTU on the Raccoon River. BOD concentrations were low, being below 3 mg/l. Ammonia nitrogen concentrations were low. Total ammonia concentrations ranged from 0.04 mg/l to 0.12 mg/l, with the highest concentration being seen at Station 10 on the Raccoon River near Van Meter. Nitrite plus nitrate nitrogen concentrations continued to be high, with concentrations on December 8 above 10 mg/l at all sites. The maximum concentration this month was 13.5 mg/l at Station 10 on the Raccoon River. Last December nitrite plus nitrate concentrations were low with the maximum concentration, occurring at Station 10, being only 3.42 mg/l (when the flow was only 220 ft 3 /s). The long-term average nitrite plus nitrate concentration for December ( ) at the comparable locations Station 1 on the Des Moines River and Station 10 on the Raccoon River were 6.86 mg/l and 7.75 mg/l, respectively. This December the nitrite plus nitrate nitrogen concentration at these sites was 12.3 mg/l and 13.5 mg/l, respectively. The maximum nitrite plus nitrate nitrogen concentration at Station 1 since December 1967 was 15.4 mg/l on December 14, The maximum nitrite plus nitrate nitrogen concentration at Station 10 since December 1972 was 14.9 mg/l also on December 14, Long-term data show that monthly mean nitrate concentrations usually peak in the spring and December, even though that was not the case last year. Orthophosphate concentrations ranged from <0.06 mg/l to 0.25 mg/l, and total phosphate concentrations ranged from 0.21 mg/l to 0.86 mg/l. Dissolved silica concentrations were moderate ranging from 14.0 mg/l at Station 1 to 16.3 mg/l at Station 9 (Des Moines River below Red Rock Dam) and Station 10. Lower silica concentrations indicate active diatom growth. Total gas pressure was measured below both reservoirs with a reconditioned Common Sensing meter model TB-F. Total gas pressure below Saylorville and Red Rock reservoirs on December 8 was 111% of saturation and 113% of saturation, respectively. 01/20/15 T:\CCEE\Private\lutz share\files\saylrr\word\monthly\dec14\dec14.doc

3 Des Moines River Water Quality Network A quarterly analysis of selected heavy metals was performed. No concentrations above detection limits for soluble cadmium (0.3 µg/l), soluble copper (1 µg/l), soluble lead (1.0 µg/l) and soluble mercury (0.05 µg/l) were noted. 01/20/15 T:\CCEE\Private\lutz share\files\saylrr\word\monthly\dec14\dec14.doc

4 Date Site Time (CDT, CST) Flow (cfs) Elevation (ft NGVD) Temp (degree C) Secchi (m) Ca Hard (mg/l as CaCO3) T Hard (mg/l as CaCO3) 12/8/ , /8/2014 4S /8/ , /8/ /8/ , /8/2014 8S /8/ ,

5 Date SITE PH CO2 P Alk T Alk Spec Cond Turbidity Sus Solids 12/8/ /8/ /8/ /8/ /8/

6 Date SITE DO BOD TOC Silica (mg/l) (mg/l) (mg/l) (mg/l) 12/8/ /8/ /8/ /8/ /8/

7 Date SITE NH4 NH3 NO2+NO3 Org N Tot N O-Phos T Phos (mg/l) (mg/l) (mg/l) (mg/l) (mg/l) (mg/l as (mg/l as PO4) PO4) 12/8/ /8/ /8/ < /8/ /8/

8 Date SITE TGP N2P O2P Delta P Delta N2 Delta O2 (%sat) (%sat) (%sat) (mmhg) (mmhg) (mmhg) 12/8/ /8/ /8/ /8/ /8/

9 Date Site Sol Cd Sol Cu Sol Pb Sol Hg (ug/l) (ug/l) (ug/l) (ug/l) 12/8/ <.3 < 1 < 1.0 <.05 12/8/ <.3 < 1 < 1.0 <.05 12/8/ <.3 < 1 < 1.0 <.05 12/8/ <.3 < 1 < 1.0 <.05