BIG LAKE -- SKAGIT COUNTY: 1995

Size (acres)                         520
Maximum Depth (feet)                  23
Mean Depth (feet)                     14
Lake Volume (acre-feet)             7280
Drainage Area (square miles)       22.40
Altitude (feet)                       81
Shoreline Length (miles)             6.2

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 ________________________________________________________________________________________________________________________ There are no Secchi data available for 1995. ________________________________________________________________________________________________________________________
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 95/05/21 E 20 0.44 11.8 10 1.8 95/05/21 H 22 0.38 95/09/06 E 25 0.24 10.5 13 25S 1.2 95/09/06 H ________________________________________________________________________________________________________________________ E=epilimnion composite, H=hypolimnion composite. Remarks codes: U = Below detection limits; J = Estimate.
SUMMARY OF VOLUNTEER SURVEY There was no survey response for 1995. FIELD OBSERVATIONS OF ECOLOGY STAFF Brazilian elodia (Egeria densa) was observed while surveying the lake. This lake suffered a significant fish kill early in the spring. The kill was most likely due to natural causes but these natural causes may be indirectly related to poor water quality.
TROPHIC STATUS Estimated Trophic State: Meso-eutrophic Mean Trophic State Index (Secchi): 46N* (Mesotrophic) Mean Trophic State Index (Total Phosphorus): 51 (Meso-eutrophic) Mean Trophic State Index (Chlorophyll a): 54 (Eutrophic) *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 Big is classified as meso-eutrophic based on the significant amount of phosphorus and chlorophyll detected in the epilimnion. An additional sign of eutrophy was the abundant blue-green algal cells observed during the summer survey. The nearly anoxic hypolimnion is an additional sign of eutrophy.
COMMENTS FROM 94/08/23 AQUATIC PLANT SURVEY many macrophytes, especially where not harvested. Few M. spicatum plants, only at sites 1 and 2. Did not survey entire shoreline. Met with 3 residents, Shelee King, Carole, Mac Maximum depth of plant growth: 5.0M.
AQUATIC PLANT LIST (This list may be from multiple years and sources.) Brasenia schreberi (watershield) Carex sp. (sedge) Ceratophyllum demersum (Coontail; hornwort) Egeria densa (Brazilian elodea) Elodea canadensis (common elodea) Elodea sp. (waterweed) Iris pseudacorus (yellow flag) Juncus sp. (rush) Myriophyllum spicatum (Eurasian water-milfoil) Najas flexilis (common naiad) Nitella sp. (stonewort) Nuphar lutea (yellow water-lily) Nuphar polysepala (spatter-dock, yellow water-lily) Nymphaea odorata (fragrant waterlily) Potamogeton crispus (curly leaf pondweed) Potamogeton diversifolius (snailseed pondweed, diverse leaf pondweed) Potamogeton epihydrus (ribbonleaf pondweed) Potamogeton foliosus (leafy pondweed) Potamogeton gramineus (grass-leaved pondweed) Potamogeton pectinatus (sago pondweed) Potamogeton praelongus (whitestem pondweed) Potamogeton pusillus (slender pondweed) Potamogeton richardsonii (Richardson's pondweed) Potamogeton robbinsii (fern leaf pondweed) Potamogeton sp (thin leaved) (thin leaved pondweed) Potamogeton sp (thin leaved) or Heteranthera dubia (thin leaved pondweed-like) Potamogeton zosteriformis (eel-grass pondweed) Scirpus sp. (bulrush) Typha latifolia (common cat-tail) Typha sp. (cat-tail) Utricularia vulgaris (common bladderwort) Vallisneria americana (water celery)


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

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