State: Lake Hopatcong Shallow by 2 Feet

Heads up, Lake Hopatcong boaters.

The state Department of Environmental Protection approved a temporary reduction of outflow from the Lake Hopatcong dam to the Musconetcong River. The lake's low water level is expected to be the main topic during Monday night's Lake Hopatcong Commission meeting in Roxbury.

DEP representative to the commission, Kerry Pflugh, recently detailed the circumstances relating to the lake's outflow reduction to the the river.

Read more below.

Per the provisions in the Lake Hopatcong Water Level Management Plan and the required assessment and recommendation from Division of Fish and Wildlife (DFW) staff, Assistant Commissioner Rich Boornazian in consultation with Assistant Commissioner of Water Resources Michele Siekerka has approved a temporary reduction of outflow from the Lake Hopatcong Dam to the Musconetcong River. The NJDEP will continue to carefully monitor the situation and return the outflow back to 12cfs as soon as conditions in the river indicate stress.  Again this is a temporary reduction.

The following facts reflect recent and current circumstances in Lake Hopatcong and in the Musconetcong River immediately downstream of the Lake Hopatcong dam:

1.  The lake was lowered over the winter approximately 26", per the Lake Hopatcong Water Level Management Plan. Refilling of the lake was initiated earlier than usual this year due to the lack of ice cover on the lake and in recognition of minimal rainfall.  On Feb. 18 the passing flow was reduced from  approx. 23 CFS to 12 CFS (data from USGS website) to accelerate the rate of refill.  Unfortunately the lake has not refilled appreciably due to minimal rainfall.  The lake level is currently at 7.10 ft (gage height), which is 1.9 ft below normal pool elevation (gage height of the crest of the dam at Lake Hopatcong is 9.0 feet).

2.  Provisional data  obtained from the Office of the NJ State Climatologist website (http://climate.rutgers.edu/stateclim_v1/data/north_njhistprecip.html) indicates that the monthly precipitation for northern NJ for the past 3 months (Jan - Mar) was 5.82".    The Plan states (p. 32) that "In the event that spring precipitation for any preceding three months is less than seven (7) inches in aggregate, (eight inches following a 60 inch drawdown) the Assistant Commissioner for Natural and Historic Resources, after consultation with, and upon the advice and consent from, the Commissioner for Water Resources may reduce the passing flow out of Lake Hopatcong below the normal 12 CFS passing flow." 

3.  Water temperatures were taken at several locations in the Musconetcong River on Monday, April 9 (mid-morning) by DFW.  Water temperatures ranged from 9.4 - 10.8°C, which are well below the temperature criterion for trout maintenance waters (not to exceed an absolute maximum of 25°C (77°F) and not to exceed a rolling seven day average of maximum temperatures of 23°C (73.4°F); N.J.A.C. 7:9B-1.14(d)11.).  Existing flow conditions in the river between Lake Hopatcong and Lake Musconetcong were considered adequate to support the fisheries and water was flowing over the Lake Musconetcong dam. Note that the opening day of recreational trout fishing was on Saturday, April 7 and trout stocking occurs weekly, for the next 7 Fridays, through May 25.

4.  In light of abnormal circumstances (lack of precipitation) and current river conditions, NJDFW supports a temporary reduction in the passing flow, from 12 CFS to 8.2 CFS.  In our best professional judgment, a temporary reduction is not expected to jeopardize the downstream aquatic resources.  DFW will continue to monitor stream and weather conditions to determine when a minimum passing flow of 12 CFS must be reinstated to protect downstream resource.