CONCONULLY LAKE -- OKANOGAN COUNTY: 1997

The south end of Conconully Lake is located at Conconully. It is an artificial reservoir created in 1919-1921 by damming Salmon Creek. It is fed by the North Fork of Salmon Creek, which enters Conconully Lake just above the dam. The lake drains south via Salmon Creek to Conconully Reservoir. Before Salmon Creek was dammed, the lake was known as Salmon Lake.

Size (acres)                         273
Maximum Depth (feet)                 109
Mean Depth (feet)                     47
Lake Volume (acre-feet)            12831
Drainage Area (square miles)       50.30
Altitude (feet)                     2287
Shoreline Length (miles)             6.8

Contour Map

Source of morphometric data: Water Supply Bulletins 42, 43, and 57.


VOLUNTEER-COLLECTED SECCHI DATA
________________________________________________________________________________________________________________________
Date      Temperature      Water      %Cloud Recent        Secchi Lake  
(Y/M/D)    (C)   (F)  pH   Color      Cover  Rain   Wind   (ft)   Ht(in) Abbrev. Comments
________________________________________________________________________________________________________________________
        STATION 1
97/05/03   9.0  48.2       Mod Green    75   Light  Light  11.0     0.0  WATER LEVEL AT 75%
97/05/11  10.0  50.0                    50   Light  Calm   11.5     0.0  WATER LEVEL AT 78%
97/05/17   8.9  48.0       Lt Green     50   Trace  Strong 17.0     0.0  
97/08/18  22.2  72.0       Undefined    40          Calm   19.0     0.0  WATER WAS APPLE GREEN.
________________________________________________________________________________________________________________________
   
LABORATORY RESULTS
________________________________________________________________________________________________________________________
                    Total       Total                   Fecal Col. Bacteria  Turb-    Suspended Solids           
                    Phosphorus  Nitrogen   Chlorophyll  (colonies/100 mL)    idity    Total   Non-Volatile   Color  
Date         Strata (ug/L)      (mg/L)     (ug/L)       Site 1    Site 2     (NTU)    (mg/L)  (mg/L)         (Pt-Co)
________________________________________________________________________________________________________________________
        STATION 1
97/05/19       E      38        0.23                                         13.0                                
97/05/19       H      55        0.25                                                                             
97/08/18       E      13        0.20        4.3                                                                  
97/08/18       H      86        0.28                                                                             
________________________________________________________________________________________________________________________
E=epilimnion composite, H=hypolimnion composite.  Remarks codes: U = Below detection limits; J = Estimate.


SUMMARY OF VOLUNTEER SURVEY


There was no survey response for 1997.

FIELD OBSERVATIONS OF ECOLOGY STAFF
At spring sampling, pool was about 80% full. In summer, Aphanizomenon in 5 and 10M
samples, Anabaena (?) at 1,3, and 5M.  Slight H2S smell at 20M.

TROPHIC STATUS
Estimated Trophic State:                                 Mesotrophic
Mean Trophic State Index (Secchi):                       36N* (Oligotrophic)
Mean Trophic State Index (Total Phosphorus):             41 (Oligo-mesotrophic)
Mean Trophic State Index (Chlorophyll a):                45 (Mesotrophic)

*The calculated TSI is an estimate.  The Secchi disk hit bottom (B), entered the weeds
(W), or there were too few valid readings (N), or the calculation was based on
qualified data (J), or TSIP was based on spring data (S).

SUMMARY AND EXPLANATION OF TROPHIC STATE ASSESSMENT
Conconully appears to be highly productive in the summer.  This is demonstrated by
elevated epilimnetic chlorophyll concentrations and pH readings.  The depleted oxygen 
concentration in the summertime hypolimnion, the presence of blue-green algae and the
slight smell of H2S from the hypolimnion further support the mesotrophic assessment.  

COMMENTS FROM 94/07/26 AQUATIC PLANT SURVEY
sunny, slight breeze.  milfoil with characteristics of M. spicatum and M. sibiricum
widely distributed.  Dominant macrophytes were P. illinoensis, Myriophyllum,
Ceratophyllum demersum.  Maximum depth of plant growth:  6.5M. 

AQUATIC PLANT LIST  (This list may be from multiple years and sources.)
Alisma gramineum (narrowleaf water-plantain)  Callitriche
hermaphroditica (northern water-starwort)  Ceratophyllum demersum 
(Coontail; hornwort)  Chara sp. (muskwort)  Elodea canadensis (common
elodea)  Myriophyllum sibiricum (northern watermilfoil)  Myriophyllum
sp. (water-milfoil)  Myriophyllum spicatum (Eurasian water-milfoil)  
Nitella sp. (stonewort)  Potamogeton foliosus (leafy pondweed)  
Potamogeton illinoensis (Illinois pondweed)  Potamogeton pectinatus 
(sago pondweed)  Potamogeton sp (thin leaved) (thin leaved pondweed)  
Potamogeton sp (thin leaved) or Heteranthera dubia (thin leaved pondweed-like)
Potamogeton sp. (pondweed)  Ranunculus aquatilis (water-buttercup)  
Scirpus sp. (bulrush)  unknown plant (unknown)

Data collected and provided by Washington Department of Ecology's Lake Monitoring Program (Maggie Bell-McKinnon, phone 360-407-6124).

Go To: