LOST LAKE -- SNOHOMISH COUNTY: 1996

Size (acres)                          13
Maximum Depth (feet)                  45
Mean Depth (feet)                     23
Lake Volume (acre-feet)              299
Drainage Area (square miles)        0.20
Altitude (feet)                      445
Shoreline Length (miles)             0.7

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 96/06/04 0 7.0 0.0 BASIN LAKE ________________________________________________________________________________________________________________________

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 96/06/04 E 19 0.46 5.4 23 15 1.5 96/06/04 H 26 0.99 96/08/20 E 18 0.40 8.3 1.1 96/08/20 H 19 0.69 ________________________________________________________________________________________________________________________ E=epilimnion composite, H=hypolimnion composite. Remarks codes: U = Below detection limits; J = Estimate.

SUMMARY OF VOLUNTEER SURVEY There was no survey response for 1996. FIELD OBSERVATIONS OF ECOLOGY STAFF Approximately 50% of the shoreline was covered with natural vegetation, mostly alder and Spiraea douglasii. All macrophytes were observed in low abundance. Observed species included: Brasenia schreberi, Nuphar lutea, Salix sp., Iris pseudacorus and Typha latifolia.

TROPHIC STATUS Estimated Trophic State: Meso-eutrophic Mean Trophic State Index (Secchi): 48N* (Meso-eutrophic) Mean Trophic State Index (Total Phosphorus): 46 (Mesotrophic) Mean Trophic State Index (Chlorophyll a): 49 (Meso-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 Lost Lake is classified as meso-eutrophic. Secchi readings were taken late in the day so Secchi TSI would most likely be lower if Secchi dips had been taken near mid-day. All TSIs support a mesotrophic classification but significant summertime hypolimnetic dissolved oxygen depletion supports a classification more eutrophic.

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

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